EJB3持久化实例

        EJB3持久化实例。

        要实现EJB3的持久化，必须经过以下步骤：

            1)    配置数据源连接;

            2)    在配置文件 persistence.xml 中指定数据源;

            3)    开发实体Bean;

            4)    在SessionBean , Java SE 或 Java EE 中调用实体Bean。

        下面是EJB3持久化的具体流程：

            1)    配置数据源连接。在JBoss6配置Mysql数据源是这样的：将Mysql驱动复制到D:\jboss\server\default\lib目录 ;   然后，复制D:\jboss\docs\examples\jca\mysql-ds.xml到JBoss部署目录D:\jboss\server\default\deploy中，并修改配置参数如下：       

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

<!-- See http://www.jboss.org/community/wiki/Multiple1PC for information about local-tx-datasource -->
<!-- $Id: mysql-ds.xml 97536 2009-12-08 14:05:07Z jesper.pedersen $ -->
<!--  Datasource config for MySQL using 3.0.9 available from:
http://www.mysql.com/downloads/api-jdbc-stable.html
-->

<datasources>
  <local-tx-datasource>
    <jndi-name>MySqlDS</jndi-name>
    <connection-url>jdbc:mysql://localhost:3306/ejb</connection-url>
    <driver-class>com.mysql.jdbc.Driver</driver-class>
    <user-name>root</user-name>
    <password>123456</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name>
    <!-- should only be used on drivers after 3.22.1 with "ping" support
    <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker</valid-connection-checker-class-name>
    -->
    <!-- sql to call when connection is created
    <new-connection-sql>some arbitrary sql</new-connection-sql>
      -->
    <!-- sql to call on an existing pooled connection when it is obtained from pool - MySQLValidConnectionChecker is preferred for newer drivers
    <check-valid-connection-sql>some arbitrary sql</check-valid-connection-sql>
      -->

    <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml (optional) -->
    <metadata>
       <type-mapping>mySQL</type-mapping>
    </metadata>
  </local-tx-datasource>
</datasources>

            2)    指定数据源，配置persistence.xml。下面是配置persistence.xml的实例：

<?xml version="1.0" encoding="UTF-8"?>
<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="EJB_EntityBean" transaction-type="JTA">  
        <jta-data-source>java:/MySqlDS</jta-data-source>  
        <properties>  
            <property name="hibernate.hbm2ddl.auto" value="update"/>  
            <!-- 显示最终执行的SQL -->  
            <property name="hibernate.show_sql" value="true"/>  
            <!-- 格式化显示的SQL -->  
            <property name="hibernate.format_sql" value="true"/>  
        </properties>  
    </persistence-unit> 
</persistence>

            3)    开发EntityBean，User.java。

package com.ejb.entitybean;

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;

@SuppressWarnings("serial")
@Entity
@Table(name = "user")
public class User implements Serializable{ 
	
	private Integer id;
	private String userName;
	private String password;
	
	public User(){
	}

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	public Integer getId() {
		return id;
	}

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

	@Column(nullable=false,length=60)
	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}
		
	@Column(nullable=false,length=60)
	public String getPassword() {
		return password;
	}

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

          4)    开发SessionBean进行调用。远程接口类，UserDao.java。

package com.ejb.dao;

import com.ejb.entitybean.User;

public interface UserDao {
	
	public boolean insert(User user);
	
	public User selectById(int userId);
	
	public boolean update(User user);
	
	public boolean deleteById(int userId);

}

            5)    实现类，UserDaoBean.java

package com.ejb.dao.impl;

import javax.ejb.Remote;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import com.ejb.dao.UserDao;
import com.ejb.entitybean.User;

@Stateless
@Remote(UserDao.class)
public class UserDaoBean implements UserDao{
	
	@PersistenceContext
	protected EntityManager em;

	public boolean insert(User user) {
		try {
			em.persist(user);
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}

	public User selectById(int userId) {
		User user = em.find(User.class, Integer.valueOf(userId));
		return user;
	}

	public boolean update(User user) {
		try {
			em.merge(user);
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}

	public boolean deleteById(int userId) {
		try {
			User user = em.find(User.class, Integer.valueOf(userId));
			em.remove(user);
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}

}

            6)    发布到JBoss服务器，然后开发客户端进行测试。    引入D:\jboss\client目录下的jar包，并引入服务端项目。开发如下代码：

package com.ejb.test;

import javax.naming.InitialContext;

import org.junit.BeforeClass;
import org.junit.Test;

import com.ejb.dao.UserDao;
import com.ejb.entitybean.User;



public class UserDaoTest {
	
	private static UserDao userDao = null;
	
	@BeforeClass
	public static void beforeClass() throws Exception{
		InitialContext ctx = new InitialContext();
		userDao = (UserDao)ctx.lookup("UserDaoBean/remote");
	}
	
	@Test
	public void testInsert() throws Exception{
		User user = new User();
		user.setUserName("admin");
		user.setPassword("123456");
		if(userDao.insert(user)){
			System.out.println("添加成功！");
		}
		else{
			System.out.println("添加失败！");
		}
	}
	
	@Test
	public void testSelectById(){
		User user = userDao.selectById(3);
		System.out.println("======>id:"+user.getId()+" userName:"+user.getUserName()+"   password:"+user.getPassword());
	}
	
	@Test
	public void testUpdate(){
		User u = new User();
		u.setId(3);
		u.setUserName("莫言");
		u.setPassword("123");
		if(userDao.update(u)){
			System.out.println("更新成功！");
		}
		else{
			System.out.println("更新失败！");
		}
	}
	
	@Test
	public void testDelete(){
		if(userDao.deleteById(1)){
			System.out.println("删除成功！");
		}
		else{
			System.out.println("删除失败！");
		}
	}
	
}

            7)        执行测试。执行testInsert()方法。

                    控制台中客户端输出：

2012-11-03 11:09:34  INFO  Client[14848295:5c4o12t-hxzaqp-h925lov3-1-h925lpdq-4] is disconnected
添加成功！

                    控制台中服务端输出：

11:09:28,796 WARN  [org.jboss.ejb3.TimerServiceContainer] EJBTHREE-2193: using deprecated TimerServiceFactory for restoring timers
11:09:34,227 INFO  [STDOUT] Hibernate: 
11:09:34,227 INFO  [STDOUT]     insert 
11:09:34,227 INFO  [STDOUT]     into
11:09:34,227 INFO  [STDOUT]         user
11:09:34,227 INFO  [STDOUT]         (password, userName) 
11:09:34,227 INFO  [STDOUT]     values
11:09:34,227 INFO  [STDOUT]         (?, ?)