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How to read Entity get object by id in Spring+JPA+Hibernate using Entity Manager
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Jpa EntityManagers get method used to get the object by primary key value.

@PersistentContext annotation used to inject the LocalContainerEntityManager instance at runtime.
em.get(1); returns the entity object of the table's row data.
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StudentInfo.java
package com.knowledgewalls.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity(name="STUDENT_INFO")
public class StudentInfo {
    @Id
    @Column(name="STUDENT_ID")
    private int studentId;
    
    @Column(name="STUDENT_NAME")
    private String StudentName;

    public int getStudentId() {
        return studentId;
    }
    public void setStudentId(int studentId) {
        this.studentId = studentId;
    }

    public String getStudentName() {
        return StudentName;
    }
    public void setStudentName(String studentName) {
        StudentName = studentName;
    }    
}
StudentInfoDAO.java
package com.knowledgewalls.dao;

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

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

import com.knowledgewalls.entity.StudentInfo;

@Repository
@Transactional
public class StudentInfoDAO {
    
    @PersistenceContext
    EntityManager em;
    
    public void save(StudentInfo userDetails){
        System.out.println("Called for; Student:"+userDetails.getStudentId());

        try {
            em.persist(userDetails);
        }
        catch(Exception e){
            System.out.println("Insertion Failure; Student:"+userDetails.getStudentId());
            e.printStackTrace();
        }
    }
    
    public StudentInfo get(int id){
        try {
            StudentInfo studentInfo = em.find(StudentInfo.class, id);
            return studentInfo;
        }
        catch(Exception e){
            System.out.println("Get failed. id:"+id);
            e.printStackTrace();
            return  null;
        }
    }
}
StudentInfoController.java
package com.knowledgewalls.controller;

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.knowledgewalls.dao.StudentInfoDAO;
import com.knowledgewalls.entity.StudentInfo;

@Controller
public class StudentInfoController {
    
    @Autowired
    StudentInfoDAO studentInfoDAO;
    
    @RequestMapping(value="/addNGetStudent",method=RequestMethod.GET)
    public @ResponseBody StudentInfo addUsers(){
        {
            StudentInfo studentInfo = new StudentInfo();
                studentInfo.setStudentId(1);
                studentInfo.setStudentName("Raj");
                    
            studentInfoDAO.save(studentInfo);
        }
        
        StudentInfo studentInfo = studentInfoDAO.get(1);
        return studentInfo;
    }
}
Persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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" >

  <persistence-unit name="hibernatePersistenceUnit">
          <properties>
            <property name="hibernate.hbm2ddl.auto" value="create" />
        </properties>
  </persistence-unit>

</persistence>
Beans-servlet.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:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-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/mvc http://www.springframework.org/schema/mvc/spring-mvc-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/util http://www.springframework.org/schema/util/spring-util-3.0.xsd">

    <context:component-scan base-package="com.knowledgewalls" />
    <mvc:annotation-driven />
    <tx:annotation-driven transaction-manager="transactionManager" />
    
    <bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceXmlLocation" value="classpath*:persistence.xml" />
        <property name="persistenceUnitName" value="hibernatePersistenceUnit" />
        <property name="dataSource" ref="dataSource"/>
        <property name="jpaVendorAdapter" ref="jpaVendorAdapter"/>
    </bean>
    
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <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="mysql" />
        <property name="initialSize" value="5" />
        <property name="maxActive" value="10" />
    </bean>
    
    <bean id="jpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
        <property name="database" value="MYSQL"></property>
        <property name="showSql" value="true"></property>
        <property name="generateDdl" value="false"></property>
        <property name="databasePlatform" value="org.hibernate.dialect.MySQL5InnoDBDialect"></property>
    </bean>
    
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
         <property name="entityManagerFactory" ref="emf" />
    </bean>
    
    <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" />
    <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/>
    <bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>

</beans>
Web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Hibernate003_ReadingModelObject</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
 
  <servlet>
    <servlet-name>beans</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>beans</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>
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