Spring Integration with JPA/Hibernate using maven – I

Hi all here is my post regarding integration of some of the best frameworks available in the market, Spring+JPA/Hibernate.
Spring’s Basic concept: Inversion of Control

The basic concept of spring is the Inversion of Control pattern (dependency injection). In Spring, programmers don’t need to create user objects but they need to describe how they should be created (in applicationContext.xml or using annotations). Programmers need not directly connect components and services together in code but describe which services are needed by which components in a configuration file or using annotations. The spring container is responsible for all this. Spring creates all the objects, connects them together by setting the necessary properties, and determines when methods will be invoked.
So using Spring framework the integration between technologies become loosely coupled.

Requirements:
Spring 3.1
JPA2.x/Hibernate 3.x
Eclipse 4.2 with Maven
Mysql Database

The major parts of the Credentials application explained below are:

The Entity classes
The DAO class which will contain common db operation code and functions
The service class – which is the actual business class.. This will contain actual business logic in it. In our example, we save Credentials bean information using this class.
Explained in the next tutorial
The client – The client can be a jsp / jsf web components or it can be a simple java program, which gets the service bean from spring and calls business method.
The spring’s applicationContext.xml descriptor which specifies what are the objects to be created when starting the application and where they should be injected.

Let’s go through the tutorial step by step.You can download the full project code at the end of the tutorial:
i explain how to Retrieve and Insert and leave Delete and Update to be coded yourself(for fun).

Step1:create a maven project in eclipse.
step2:update the pom.xml file as shown below.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.spark.spring</groupId>
	<artifactId>SpringIntegration</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
	<name>SpringIntegration</name>
	<description>SpringIntegration</description>

	<properties>
		<org.slf4j-version>1.6.1</org.slf4j-version>
	</properties>

	<dependencies>

		<dependency>
			<groupId>cglib</groupId>
			<artifactId>cglib</artifactId>
			<version>2.2</version>
		</dependency>
		<dependency>
			<groupId>net.sf.ezmorph</groupId>
			<artifactId>ezmorph</artifactId>
			<version>1.0.6</version>
		</dependency>
		<dependency>
			<groupId>commons-collections</groupId>
			<artifactId>commons-collections</artifactId>
			<version>3.2.1</version>
		</dependency>
		<dependency>
			<groupId>commons-beanutils</groupId>
			<artifactId>commons-beanutils</artifactId>
			<version>1.8.3</version>
		</dependency>
		<dependency>
			<groupId>commons-lang</groupId>
			<artifactId>commons-lang</artifactId>
			<version>2.6</version>
		</dependency>
		<dependency>
			<groupId>net.sf.json-lib</groupId>
			<artifactId>json-lib</artifactId>
			<version>2.4</version>
			<classifier>jdk15</classifier>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.18</version>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<version>2.5</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>commons-logging</groupId>
			<artifactId>commons-logging</artifactId>
			<version>1.1.1</version>
		</dependency>
		<dependency>
			<groupId>commons-httpclient</groupId>
			<artifactId>commons-httpclient</artifactId>
			<version>3.1</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-beans</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-expression</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-jdbc</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-orm</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-tx</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<!-- Spring Security -->
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-web</artifactId>
			<version>3.1.0.RELEASE</version>
			<exclusions>
				<!-- Exclude Commons Logging in favor of SLF4j -->
				<exclusion>
					<groupId>commons-logging</groupId>
					<artifactId>commons-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-taglibs</artifactId>
			<version>3.1.0.RELEASE</version>
			<exclusions>
				<!-- Exclude Commons Logging in favor of SLF4j -->
				<exclusion>
					<groupId>commons-logging</groupId>
					<artifactId>commons-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-config</artifactId>
			<version>3.1.0.RELEASE</version>
			<exclusions>
				<!-- Exclude Commons Logging in favor of SLF4j -->
				<exclusion>
					<groupId>commons-logging</groupId>
					<artifactId>commons-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-crypto</artifactId>
			<version>3.1.0.RELEASE</version>
		</dependency>

		<!-- Logging -->
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>${org.slf4j-version}</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>jcl-over-slf4j</artifactId>
			<version>${org.slf4j-version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
			<version>${org.slf4j-version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.16</version>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjrt</artifactId>
			<version>1.6.10</version>
		</dependency>


		<!-- @Inject -->
		<dependency>
			<groupId>javax.inject</groupId>
			<artifactId>javax.inject</artifactId>
			<version>1</version>
		</dependency>

		<!-- Servlet -->
		<dependency>
			<groupId>javax.servlet.jsp</groupId>
			<artifactId>jsp-api</artifactId>
			<version>2.1</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>jstl</artifactId>
			<version>1.2</version>
		</dependency>

		<!-- Hibernate Validator -->
		<dependency>
			<groupId>javax.validation</groupId>
			<artifactId>validation-api</artifactId>
			<version>1.0.0.GA</version>
		</dependency>

		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-validator</artifactId>
			<version>4.2.0.CR1</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>3.4.0.GA</version>
		</dependency>
		<dependency>
			<groupId>commons-fileupload</groupId>
			<artifactId>commons-fileupload</artifactId>
			<version>1.2.2</version>
		</dependency>
		<dependency>
			<groupId>commons-io</groupId>
			<artifactId>commons-io</artifactId>
			<version>2.2</version>
		</dependency>
		<dependency>
			<groupId>commons-dbcp</groupId>
			<artifactId>commons-dbcp</artifactId>
			<version>1.4</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aspects</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>

	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<configuration>
					<source>1.6</source>
					<target>1.6</target>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.codehaus.mojo</groupId>
				<artifactId>tomcat-maven-plugin</artifactId>
				<version>1.0-beta-1</version>
			</plugin>
			<plugin>
				<groupId>org.mortbay.jetty</groupId>
				<artifactId>jetty-maven-plugin</artifactId>
				<version>7.4.0.v20110414</version>
				<configuration></configuration>
			</plugin>
		</plugins>
		<pluginManagement>
			<plugins>
				<!--This plugin's configuration is used to store Eclipse m2e settings 
					only. It has no influence on the Maven build itself. -->
				<plugin>
					<groupId>org.eclipse.m2e</groupId>
					<artifactId>lifecycle-mapping</artifactId>
					<version>1.0.0</version>
					<configuration>
						<lifecycleMappingMetadata>
							<pluginExecutions>
								<pluginExecution>
									<pluginExecutionFilter>
										<groupId>
											org.apache.maven.plugins
										</groupId>
										<artifactId>
											maven-compiler-plugin
										</artifactId>
										<versionRange>
											[2.3.2,)
										</versionRange>
										<goals>
											<goal>compile</goal>
											<goal>testCompile</goal>
										</goals>
									</pluginExecutionFilter>
									<action>
										<ignore></ignore>
									</action>
								</pluginExecution>
							</pluginExecutions>
						</lifecycleMappingMetadata>
					</configuration>
				</plugin>
			</plugins>
		</pluginManagement>
	</build>
	<!-- needed for XmlSchema -->
	<repositories>
		<repository>
			<id>ibiblio</id>
			<name>ibiblio maven repository</name>
			<url>http://ibiblio.org/maven/</url>
			<layout>legacy</layout>
		</repository>
		<repository>
			<id>apache</id>
			<name>Apache maven repository</name>
			<url>http://www.apache.org/dist/java-repository/</url>
			<layout>legacy</layout>
		</repository>
	</repositories>

</project>

Step3:put web.xml in src/main/webapp/WEB-INF/ as shown below.

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

	<!-- Defines all the spring context information for all servlets and Filters 
		that share the info -->
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:application-context.xml</param-value>
	</context-param>

	<!-- creates spring container listener shared by all servlets and Filters -->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>

	<!-- request processing servlet -->
	<servlet>
		<servlet-name>spring</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:spring-context.xml</param-value>
		</init-param>
	</servlet>

	<servlet-mapping>
		<servlet-name>spring</servlet-name>
		<url-pattern>/spring/*</url-pattern>
	</servlet-mapping>
	
	<welcome-file-list>
		<welcome-file>pages/index.jsp</welcome-file>
	</welcome-file-list>
</web-app>

put all the configuration files in the src/main/resources folder of your maven project.

Step4: lets code our first configuration file “application-context.xml” as shown below.

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
			http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
			http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
			http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
			http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.5.xsd
			http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

	<!-- component scan for @component,@Repositry,@Service -->
	<context:component-scan base-package="com.spark" />
	
	<bean id="dataSource"
		class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="driverClassName" value="com.mysql.jdbc.Driver" />
		<property name="url"
			value="jdbc:mysql://localhost:3306/test" />
		<property name="username" value="root" />
		<property name="password" value="root" />
	</bean>

	<!-- JPA EntityManagerFactory -->
	<bean id="entityManagerFactory"
		class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
		p:dataSource-ref="dataSource">
		<property name="persistenceUnitName" value="MyPersistenceUnit"/> 
		<property name="jpaVendorAdapter">
			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
				<property name="database" value="MYSQL" />
				<property name="showSql" value="true" />
			</bean>
		</property>
	</bean>

	<!-- Transaction manager for a single JPA EntityManagerFactory (alternative 
		to JTA) -->
	<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"
		p:entityManagerFactory-ref="entityManagerFactory" />

	<!-- Activates various annotations to be detected in bean classes for eg 
		@Autowired -->
	<context:annotation-config />

	<!-- enable the configuration of transactional behavior based on annotations -->
	<tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true" />

	<!-- Property Configurator -->
	<bean id="propertyConfigurer"
		class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="location" value="classpath:jdbc.properties" />
	</bean>

</beans>

Step5:lets code our second configuration file “spring-context.xml” which internally imports one more configuration file “controllers.xml”, this spring-context.xml file goes as a parameter for DispatcherServlet class of Spring framework.

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

	<!-- Enables the Spring MVC @Controller programming Model -->
	<annotation-driven />

	<beans:bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<beans:property name="prefix" value="/" />
		<beans:property name="suffix" value=".html" />
	</beans:bean>

	<!-- Imports user-defined @Controller beans that process client requests -->
	<beans:import resource="controllers.xml" />

</beans:beans>

Step6: controllers.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd	
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

	<!-- Activates various annotations to be detected in bean classes -->	
	<context:annotation-config />
	<context:spring-configured />
	<!-- enable the configuration of transactional behavior based on annotations -->
	<tx:annotation-driven/>

	<!-- Scans within the base package of the application for @Components to configure as beans -->
	<context:component-scan base-package="com.spark" />
	
	
	<bean id="multipartResolver"
		class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
		<!-- one of the properties available; the maximum file size in bytes -->
		<property name="maxUploadSize" value="10000000" />
	</bean>
	
	
</beans>

Step7: Lets put the log4j.properties


log4j.rootCategory=debug, stdout, logfile

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - <%m>%n

log4j.appender.logfile=org.apache.log4j.RollingFileAppender
log4j.appender.logfile.File=C://templog/clinicComponet.log
log4j.appender.logfile.MaxFileSize=1MB

# Keep three backup files
log4j.appender.logfile.MaxBackupIndex=3
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout

#Pattern to output : date priority [category] - <message>line_separator
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - <%m>%n

So now we have finished coding our configuration just start with our logic
create the followiing packages in src/main/java folder of maven project as follows.

com.spark.controller
com.spark.dao
com.spark.service
com.spark.model

Lets start coding Java now. first step is coding our model class(POJO) as below.

/**
 * 
 */
package com.spark.model;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;

/**
 * @author Sony
 * 
 */

@Entity
@Table(name = "credentials")
@NamedQueries({
@NamedQuery(name="Credentials.getAllRecords",
    query="SELECT o FROM Credentials o")          
})
public class Credentials implements Serializable{

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	@Column(name = "ID")
	private int id;

	@Column(name = "username")
	private String username;

	@Column(name = "password")
	private String password;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
}

once our pojo is ready lets decide the business logic that is our service class. we will code an interface and its implementation class as follows

/**
 * 
 */
package com.spark.service;

import java.util.List;

import com.spark.model.Credentials;

/**
 * @author Sony
 *
 */
public interface CredentialsService {

    void save(Credentials credentials);
    Credentials findById(Long id);       
    List<Credentials> findAll();   
}

and following is the implementation class

/**
 * 
 */
package com.spark.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.spark.dao.CredentialsDao;
import com.spark.dao.CredentialsDaoImpl;
import com.spark.model.Credentials;

/**
 * @author Sony
 *
 */
@Service("credentialService")
public class CredentialsServiceImpl implements CredentialsService {

	@Autowired
	CredentialsDao credentialsDao;
	
	public CredentialsDao getCredentialsDao() {
		return credentialsDao;
	}

	public void setCredentialsDao(CredentialsDao credentialsDao) {
		this.credentialsDao = credentialsDao;
	}

	/* (non-Javadoc)
	 * @see com.spark.service.CredentialsService#save(com.spark.model.Credentials)
	 */
	@Override
	public void save(Credentials credentials) {
		// TODO Auto-generated method stub
		credentialsDao.save(credentials);

	}

	/* (non-Javadoc)
	 * @see com.spark.service.CredentialsService#findById(java.lang.Long)
	 */
	@Override
	public Credentials findById(Long id) {
		// TODO Auto-generated method stub
		return null;
	}

	/* (non-Javadoc)
	 * @see com.spark.service.CredentialsService#findAll()
	 */
	@Override
	public List<Credentials> findAll() {
		// TODO Auto-generated method stub
		return credentialsDao.findAll();
	}

}

Now its time to code our core database logic. The database logic is handled by JPA EntityManager, the object is injected into the EntityManager using the @PersistenceContext annotation its the responsibility of the Spring container to inject the EntityManager Implementation object after it scans the annotation. We will code the dao layer same as we did with service layer with an interface and its implementation class. please note that the dao is annotated as @Transactional that means the database operations will be executed under a transactional context
when spring scans the annotation.

/**
 * 
 */
package com.spark.dao;

import java.util.List;

import com.spark.model.Credentials;

/**
 * @author Sony
 *
 */
public interface CredentialsDao {

    public List<Credentials> findAll();
    public void save(Credentials credentials);
    public Credentials findById(int id);

}

following is the implementation class for the interface.

/**
 * 
 */
package com.spark.dao;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import com.spark.model.Credentials;

/**
 * @author Sony
 *
 */
@Transactional
@Component
public class CredentialsDaoImpl implements CredentialsDao {
	
	@PersistenceContext
	private EntityManager entityManager;

	public EntityManager getEntityManager() {
		return entityManager;
	}

	public void setEntityManager(EntityManager entityManager) {
		this.entityManager = entityManager;
	}

	/* (non-Javadoc)
	 * @see com.spark.dao.CredentialsDao#findAll()
	 */
	@Override
	public List<Credentials> findAll() {
		// TODO Auto-generated method stub
		List<Credentials> credentials = null;
		try {
			credentials = entityManager.createNamedQuery("Credentials.getAllRecords").getResultList();
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		return credentials;
	}

	/* (non-Javadoc)
	 * @see com.spark.dao.CredentialsDao#save(com.spark.model.Credentials)
	 */
	@Override
	public void save(Credentials credentials) {
		// TODO Auto-generated method stub
		try {
			
			entityManager.persist(credentials);
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}

	/* (non-Javadoc)
	 * @see com.spark.dao.CredentialsDao#findById(int)
	 */
	@Override
	public Credentials findById(int id) {
		// TODO Auto-generated method stub
		return null;
	}

}

Now its time to code controller which is responsible for deligating the requests to service layer and there to dao layer. In the retrieve method the response returned from the method will be a JSON String

/**
 * 
 */
package com.spark.controller;

import java.util.List;

import javax.validation.Valid;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.spark.model.Credentials;
import com.spark.service.CredentialsService;

/**
 * @author Sony
 *
 */
@Controller
public class SpringController {

	@Autowired(required=true)
	CredentialsService credentialsService;
	
	@RequestMapping(value="/insert",method=RequestMethod.POST)
	public @ResponseBody String handleInsertRequest(@Valid String username,@Valid String password){
		
		String returnStatus = "Details Saved Successfully";
				
		Credentials credentials = new Credentials();
		credentials.setUsername(username);
		credentials.setPassword(password);
		
		credentialsService.save(credentials);
		
		return returnStatus;
	}
	
	@RequestMapping(value="/retrieve",method=RequestMethod.POST)
	public @ResponseBody String handleRetrieveRequest(){
				
		List<Credentials> credentials = credentialsService.findAll();
		
		JSONObject responseDetailsJson = new JSONObject();
	    JSONArray jsonArray = new JSONArray();

	    for (int i = 0; i < credentials.size(); i++)
	    {
	      JSONObject formDetailsJson = new JSONObject();
	      formDetailsJson.put("username", credentials.get(i).getUsername());
	      formDetailsJson.put("password", credentials.get(i).getPassword());

	      jsonArray.add(formDetailsJson);
	    }
	    responseDetailsJson.put("credentials", jsonArray);
	    
	    return responseDetailsJson.toString();
		
	}
}

I will post the the UI related stuff(JSP) in the next tutorial to call the controller.

Happy Coding 🙂

Android Rest Client to call Spring MVC Project – Part 1

Hi All, This time i had very tough time to show my proof of concept to one of my colleague regarding java Spring mvc and Android. the requirement is quite direct we have to create a Spring MVC project and deploy it to server and call the spring controller using Android Activity. Thanks to spring it has released Spring-rest-template api using which we can call the business logic that is deployed in the server as spring controller. so here is my example code to you how to call spring mvc using Android Rest Client

in this part i will be explaining u how to create a spring mvc project using maven dependencies.

Note: dont code network related logic in the main thread of android activity it will lead to android.os.NetworkOnMainThreadException

Create a mavenized Spring Project as below:
Step1: POM.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.spark.android.spring</groupId>
	<artifactId>AndroidSpring</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
	<name>AndroidSpring</name>
	<description>AndroidSpring</description>

	<properties>
		<org.slf4j-version>1.6.1</org.slf4j-version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>net.sf.ezmorph</groupId>
			<artifactId>ezmorph</artifactId>
			<version>1.0.6</version>
		</dependency>
		<dependency>
			<groupId>commons-collections</groupId>
			<artifactId>commons-collections</artifactId>
			<version>3.2.1</version>
		</dependency>
		<dependency>
			<groupId>commons-beanutils</groupId>
			<artifactId>commons-beanutils</artifactId>
			<version>1.8.3</version>
		</dependency>
		<dependency>
			<groupId>commons-lang</groupId>
			<artifactId>commons-lang</artifactId>
			<version>2.6</version>
		</dependency>
		<dependency>
			<groupId>net.sf.json-lib</groupId>
			<artifactId>json-lib</artifactId>
			<version>2.4</version>
			<classifier>jdk15</classifier>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.18</version>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<version>2.5</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>commons-logging</groupId>
			<artifactId>commons-logging</artifactId>
			<version>1.1.1</version>
		</dependency>
		<dependency>
			<groupId>commons-httpclient</groupId>
			<artifactId>commons-httpclient</artifactId>
			<version>3.1</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-beans</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-expression</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-jdbc</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-orm</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-tx</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>
		<!-- Spring Security -->
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-web</artifactId>
			<version>3.1.0.RELEASE</version>
			<exclusions>
				<!-- Exclude Commons Logging in favor of SLF4j -->
				<exclusion>
					<groupId>commons-logging</groupId>
					<artifactId>commons-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-taglibs</artifactId>
			<version>3.1.0.RELEASE</version>
			<exclusions>
				<!-- Exclude Commons Logging in favor of SLF4j -->
				<exclusion>
					<groupId>commons-logging</groupId>
					<artifactId>commons-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-config</artifactId>
			<version>3.1.0.RELEASE</version>
			<exclusions>
				<!-- Exclude Commons Logging in favor of SLF4j -->
				<exclusion>
					<groupId>commons-logging</groupId>
					<artifactId>commons-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.security</groupId>
			<artifactId>spring-security-crypto</artifactId>
			<version>3.1.0.RELEASE</version>
		</dependency>

		<!-- Logging -->
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>${org.slf4j-version}</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>jcl-over-slf4j</artifactId>
			<version>${org.slf4j-version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
			<version>${org.slf4j-version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.16</version>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjrt</artifactId>
			<version>1.6.10</version>
		</dependency>

		<!-- @Inject -->
		<dependency>
			<groupId>javax.inject</groupId>
			<artifactId>javax.inject</artifactId>
			<version>1</version>
		</dependency>

		<!-- Servlet -->
		<dependency>
			<groupId>javax.servlet.jsp</groupId>
			<artifactId>jsp-api</artifactId>
			<version>2.1</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>jstl</artifactId>
			<version>1.2</version>
		</dependency>

		<!-- Hibernate Validator -->
		<dependency>
			<groupId>javax.validation</groupId>
			<artifactId>validation-api</artifactId>
			<version>1.0.0.GA</version>
		</dependency>

		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-validator</artifactId>
			<version>4.2.0.CR1</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>3.4.0.GA</version>
		</dependency>
		<dependency>
			<groupId>commons-fileupload</groupId>
			<artifactId>commons-fileupload</artifactId>
			<version>1.2.2</version>
		</dependency>
		<dependency>
			<groupId>commons-io</groupId>
			<artifactId>commons-io</artifactId>
			<version>2.2</version>
		</dependency>
		<dependency>
			<groupId>commons-dbcp</groupId>
			<artifactId>commons-dbcp</artifactId>
			<version>1.4</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aspects</artifactId>
			<version>3.1.1.RELEASE</version>
		</dependency>

	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<configuration>
					<source>1.6</source>
					<target>1.6</target>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.codehaus.mojo</groupId>
				<artifactId>tomcat-maven-plugin</artifactId>
				<version>1.0-beta-1</version>
			</plugin>
			<plugin>
				<groupId>org.mortbay.jetty</groupId>
				<artifactId>jetty-maven-plugin</artifactId>
				<version>7.4.0.v20110414</version>
				<configuration></configuration>
			</plugin>
		</plugins>
		<pluginManagement>
			<plugins>
				<!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.-->
				<plugin>
					<groupId>org.eclipse.m2e</groupId>
					<artifactId>lifecycle-mapping</artifactId>
					<version>1.0.0</version>
					<configuration>
						<lifecycleMappingMetadata>
							<pluginExecutions>
								<pluginExecution>
									<pluginExecutionFilter>
										<groupId>
											org.apache.maven.plugins
										</groupId>
										<artifactId>
											maven-compiler-plugin
										</artifactId>
										<versionRange>
											[2.3.2,)
										</versionRange>
										<goals>
											<goal>compile</goal>
											<goal>testCompile</goal>
										</goals>
									</pluginExecutionFilter>
									<action>
										<ignore></ignore>
									</action>
								</pluginExecution>
							</pluginExecutions>
						</lifecycleMappingMetadata>
					</configuration>
				</plugin>
			</plugins>
		</pluginManagement>
	</build>
	<!-- needed for XmlSchema -->
	<repositories>
		<repository>
			<id>ibiblio</id>
			<name>ibiblio maven repository</name>
			<url>http://ibiblio.org/maven/</url>
			<layout>legacy</layout>
		</repository>
		<repository>
			<id>apache</id>
			<name>Apache maven repository</name>
			<url>http://www.apache.org/dist/java-repository/</url>
			<layout>legacy</layout>
		</repository>
	</repositories>

</project>

Step2:Place all configuration files in src/main/resources of ur maven project
code for application-context.xml:

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:task="http://www.springframework.org/schema/task"
	xsi:schemaLocation="
			http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
			http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
			http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
			http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd
			http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
			http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsd">

	<!-- component scan for detecting @controller annotations -->
	<context:component-scan base-package="com.spark.android"></context:component-scan>
	
	<task:annotation-driven executor="myExecutor" scheduler="myScheduler"/>
	<task:executor id="myExecutor" pool-size="5"/>
	<task:scheduler id="myScheduler" pool-size="10"/>
	
	<tx:annotation-driven/>
	
	<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
		<property name="persistenceUnitName" value="MyPersistenceUnit" />
		<property name="dataSource" ref="dataSource" />
		<property name="jpaVendorAdapter">
			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
				<property name="showSql" value="true" />
				<property name="generateDdl" value="false" />
				<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
			</bean>
		</property>
	</bean>
	
	<bean id="dataSource"
		class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="driverClassName" value="com.mysql.jdbc.Driver" />
		<property name="url"
			value="jdbc:mysql://localhost:3306/android" />
		<property name="username" value="root" />
		<property name="password" value="root" />
	</bean>

	<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory" />
	</bean>
</beans>

code for controllers.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd	
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

	<!-- Activates various annotations to be detected in bean classes -->	
	<context:annotation-config></context:annotation-config>

	<!-- Scans within the base package of the application for @Components to configure as beans -->
	<context:component-scan base-package="com.spark.android" />
	
	
	<bean id="multipartResolver"
		class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
		<!-- one of the properties available; the maximum file size in bytes -->
		<property name="maxUploadSize" value="10000000" />
	</bean>
	
	
</beans>

code for spring-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
	xsi:schemaLocation="
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd">

	<!-- Enables the Spring MVC @Controller programming Model -->
	<annotation-driven />

	<beans:bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<beans:property name="prefix" value="/" />
		<beans:property name="suffix" value=".html" />
	</beans:bean>

	<!-- Imports user-defined @Controller beans that process client requests -->
	<beans:import resource="controllers.xml" />

</beans:beans>

For database interaction i decided to make use of JPA over Hibernate, so create a folder META-INF(All caps) in your src/main/resources/ and pleace persistence.xml file in it with the following code.

persistence.xml:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
	version="2.0">
	
	<persistence-unit name="MyPersistenceUnit" transaction-type="RESOURCE_LOCAL">
	<class>com.spark.android.model.Credentials</class>
	</persistence-unit>
	
</persistence>

now that we have completed our configuration its time for us to write the model classes and business logic for handling requests from android client and return responce. Here we use JSON for communication layer. notice that you put the code in appropriate packages.
source code for controller

/**
 * 
 */
package com.spark.android.controller;

import net.sf.json.JSON;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.spark.android.model.Credentials;

/**
 * @author Mantha Pavan Kumar
 *
 */
@Controller
public class AndroidSpringController {

	@RequestMapping(value="/insert",method=RequestMethod.POST)
	public @ResponseBody String handleInsertRequest(){
		
		Credentials credentials = new Credentials();
		credentials.setUsername("PavanKumar");
		credentials.setPassword("pavan~123!");
		
		JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON( credentials );  
		
		return jsonObject.toString();
	}
}

and following is the model class(POJO)

/**
 * 
 */
package com.spark.android.model;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

/**
 * @author Mantha Pavan Kumar
 *
 */
@Entity
@Table(name="contacts")
public class Credentials implements Serializable{

	private int id;
	private String username;
	private String password;
	
	/**
	 * @return
	 */
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	public int getId() {
		return id;
	}
	/**
	 * @param id
	 */
	public void setId(int id) {
		this.id = id;
	}
	/**
	 * @return
	 */
	@Column(name="username")
	public String getUsername() {
		return username;
	}
	/**
	 * @param username
	 */
	public void setUsername(String username) {
		this.username = username;
	}
	/**
	 * @return
	 */
	@Column(name="password")
	public String getPassword() {
		return password;
	}
	/**
	 * @param password
	 */
	public void setPassword(String password) {
		this.password = password;
	}
}

once this is ready now lets start coding your web.xml file as our project is a web application. create a folder WEB-INF(all caps) in src/main/webapps/

code for web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

	<!-- Defines all the spring context information for all servlets and Filters 
		that share the info -->
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:application-context.xml</param-value>
	</context-param>

	<!-- creates spring container listener shared by all servlets and Filters -->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>

	<!-- request processing servlet -->
	<servlet>
		<servlet-name>spring</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:spring-context.xml</param-value>
		</init-param>
	</servlet>

	<servlet-mapping>
		<servlet-name>spring</servlet-name>
		<url-pattern>/spring/*</url-pattern>
	</servlet-mapping>
	
	<welcome-file-list>
		<welcome-file>pages/index.jsp</welcome-file>
	</welcome-file-list>
</web-app>

now its time to test the application open cmd and navigate to the project folder and issue “mvn clean install package”
without quotes it will download all jar files needed by your application and it builds the war file(bueauty of maven)
now your project is ready for deployment issue the command “mvn tomcat:run” without quotes your tomcats starts and your war will be deployed now your Spring MVC project is up and running lets see how to code Android REST client and communicate with Spring Web App in Part-II.

Happy Coding 🙂

Querying Entities using JPQL and the Criteria API

When i started using EJB2.0 the only way to query the database is to use EJB QL(EJB Query Language) later on with the introduction of JavaEE 5.0 the EJB QL is Replaced by JPQL (Java Persistence Query Language). Now in today’s world, There are two primary Java EE technologies for querying a database: Java Persistence Query Language (JPQL) and the Criteria API. JPQL is similar in appearance and usage to SQL while the Criteria API provides a more type-safe and object-oriented entity querying capability.JPQL is based on the Hibernate Query Language (HQL) and is a subset of HQL. It is portable and allows queries to be executed against different data stores. This is in contrast to the use of a native query where the query is expressed in the native SQL of the data store.Another older, yet still viable technique is the Java database classes and interfaces found in the java.sql package.

Now i want to share some comparison of JPQL and CriteriaAPI:

JPQL:
String param = "Pav%"; Query query = em.createQuery( "select e from Employee e where e.firstName like :param"); query.setParameter("param", param); List<Employee> employees = query.getResultList(); for (Employee emp : employees){ System.out.println(emp.getFirstName()); }

Equivalent with Criteria API:
String param = "Pav%";

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Employee> query = cb.createQuery(Employee.class);

        Root<Employee> emp = query.from(Employee.class);
        query.where(cb.like(emp.<String>get("firstName"),
                            cb.parameter(String.class, "param")));

        TypedQuery<Employee> tq = em.createQuery(query);
        tq.setParameter("param", param);
        List<Employee> employees = tq.getResultList();

        for (Employee employee : employees){
            System.out.println(employee.getFirstName());
        }

Example of criteria API using count:
In JPQL

String param = "2000";

        Query query = em.createQuery(
             "select count(e) from Employee e where e.sal = :empSal");
        query.setParameter("empSal", param);
        Long count1 = (Long)query.getSingleResult();

        System.out.println("count : "+count1);

Equivalent with Criteria API

String param = "2000";

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Long> query = cb.createQuery(Long.class);

        Root<Employee> emp = query.from(Employee.class);
        query.select(cb.count(emp));
        query.where(cb.equal(emp.<String>get("sal"),
                             cb.parameter(String.class,"empSal")));

        TypedQuery<Long> tq = em.createQuery(query);
        tq.setParameter("empSal", param);

        Long count = tq.getSingleResult();

        System.out.println("count : "+count);

Example of criteria using distinct
In JPQL

String param = "dev%";

        Query query = em.createQuery(
             "select distinct e.disignation from Employee e where e.designation like :param");
        query.setParameter("param", param);
        List<String> desg= query.getResultList();

        for (String desgs : desg){
            System.out.println(desgs);
        }

Equivalent with Criteria API

String param = "dev%";

        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<String> query = cb.createQuery(String.class);

        Root<Employee> emp = query.from(Employee.class);
        query.select(emp.<String>get("designation"));
        query.distinct(true);

        query.where(cb.like(music.<String>get("artisteName"),
                            cb.parameter(String.class, "param")));

        TypedQuery<String> tq = em.createQuery(query);
        tq.setParameter("param", param);

        List<String> designations = tq.getResultList();


        for (String desgs : designations){
            System.out.println(desgs);
        }

Happy Coding :)