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Hints
@ElementCollection annotation is one of the annotation of jpa. This can be used with Collection of Embeddable Class. @ElementCollection has fetch attributes. fetch attribute supports Eager and Lazy types.
FetchType.EAGER: Eager fetch type fetches the data with master other datas.
FetchType.LAZY: Lazy fetch type fetches the data whenever call getter method of the object.
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create table STUDENT_ADDRESS
(STUDENT_ID integer not null,
city varchar(255),
state varchar(255)) ENGINE=InnoDB;
create table STUDENT_INFO
(STUDENT_ID integer not null auto_increment,
STUDENT_NAME varchar(255),
primary key (STUDENT_ID)) ENGINE=InnoDB;
alter table STUDENT_ADDRESS
add index FK250691B0C4B1E0F3 (STUDENT_ID),
add constraint FK250691B0C4B1E0F3 foreign key (STUDENT_ID) references STUDENT_INFO (STUDENT_ID); |
package com.knowledgewalls.entity;
import javax.persistence.Embeddable;
@Embeddable
public class Address {
private String city;
private String state;
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
} |
package com.knowledgewalls.entity;
import java.util.ArrayList;
import java.util.Collection;
import javax.persistence.Column;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
@Entity(name="STUDENT_INFO")
public class StudentInfo {
@Id @GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="STUDENT_ID")
private int studentId;
@Column(name="STUDENT_NAME")
private String StudentName;
@ElementCollection(fetch=FetchType.EAGER)
@JoinTable(name="STUDENT_ADDRESS",joinColumns=@JoinColumn(name="STUDENT_ID"))
private Collection<Address> addresses = new ArrayList<Address>();
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;
}
public Collection<Address> getAddresses() {
return addresses;
}
public void setAddresses(Collection<Address> addresses) {
this.addresses = addresses;
}
} |
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 student_id){
try {
return em.find(StudentInfo.class, student_id);
}
catch (Exception e){
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.Address;
import com.knowledgewalls.entity.StudentInfo;
@Controller
public class StudentInfoController {
@Autowired
StudentInfoDAO studentInfoDAO;
@RequestMapping(value="/addStudent",method=RequestMethod.GET)
public @ResponseBody StudentInfo addUsers(){
{
StudentInfo studentInfo = new StudentInfo();
studentInfo.setStudentName("Raj");
Address addr = new Address();
addr.setCity("City 1");
addr.setState("State 1");
Address addr2 = new Address();
addr2.setCity("City 2");
addr2.setState("State 2");
studentInfo.getAddresses().add(addr);
studentInfo.getAddresses().add(addr2);
studentInfoDAO.save(studentInfo);
}
StudentInfo studentInfo = studentInfoDAO.get(1);
System.out.println("Place Holder. 1");
System.out.println(studentInfo.getAddresses().size());
return studentInfo;
}
} |
<?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> |
<?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> |
<?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>Hibernate010_HibernateProxyNFetchLazyNEager</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> |
