在EJB 3.0 學習筆記——準備工作中只是簡單的搭好了EJB3.0開發的基本環境，之
后就可以開發最簡單的Session Bean了，我感興趣的還是Entity Bean，所以接下來
我想先試驗一下Entity Bean。
?
一、在JBoss中配置好Data Source
我使用的是MySQL數據庫，所以首先將MySQL的JDBC驅動復制到
jboss-4.0.3SP1\server\all\lib目錄，然后將jboss-4.0.3SP1\docs\examples\jca
下的mysql-ds.xml作出適當修改后復制到jboss-4.0.3SP1\server\all\deploy目錄
下，這是我修改后的mysql-ds.xml文件：
<?xml version="1.0" encoding="UTF-8"?>
<!-- $Id: mysql-ds.xml,v 1.3.2.1 2004/12/01 11:46:00 schrouf Exp $ -->
<!--? 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/test</connection-url>
??? <driver-class>com.mysql.jdbc.Driver</driver-class>
??? <user-name>test</user-name>
??? <password></password>
??? <exception-sorter-class-
name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</excepti
on-sorter-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
??? <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>
這樣之后，JBoss下的MySQL Data Source配置完成。
二、創建數據庫并編寫Entity Bean代碼
create table book(
id int not null auto_increment primary key,
title varchar(20) not null,
author varchar(40) not null
);
新建Java Project，導入User Library：EJB3_JBoss，以下是類代碼。
//Book.java
package ejb.bean.entity;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="book")
public class Book implements Serializable {
?/**
? *
? */
?private static final long serialVersionUID = 1L;
?private Integer id;?
?private String title;?
?private String author;
?
?public Book() {??
??super();?
?}?
?public Book(Integer id, String title, String author) {?
??super();??
??this.id = id;??
??this.title = title;??
??this.author = author;?
??}
?@Override
?public String toString() {?
??
??return "Book: " + getId() + " Title " + getTitle() + "
Author "?+ getAuthor();?
?}
?public String getAuthor() {
??return author;
?}
?
?@Id @GeneratedValue(strategy=GenerationType.AUTO)
?public Integer getId() {
??return id;
?}
?public String getTitle() {
??return title;
?}
?public void setAuthor(String author) {
??this.author = author;
?}
?public void setId(Integer id) {
??this.id = id;
?}
?public void setTitle(String title) {
??this.title = title;
?}
}
三、編寫一個簡單的Stateless Session Bean 并進行測試
//BookTestLocal.java
package ejb.bean.entity;
import javax.ejb.Local;
@Local
public interface BookTestLocal {
?public void test();
}
//BookTestRemote.java
package ejb.bean.entity;
import javax.ejb.Remote;
@Remote
public interface BookTestRemote {
?
?public void test();
}
//BookTestBean.java
package ejb.bean.entity;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
@Stateless
public class BookTestBean implements BookTestLocal, BookTestRemote {
?@PersistenceContext
?EntityManager em;
?public void test() {
??// TODO Auto-generated method stub
??Book book = new Book(null, "My first bean book",
"Sebastian");
??em.persist(book);
?}
}
//Client.java
package ejb.client.entity;
import ejb.bean.entity.*;
import javax.naming.InitialContext;
/**
?* Comment
?*
?* @author <a href="mailto:bill@jboss.org">Bill Burke</a>
?* @version $Revision: 1.1.6.7 $
?*/
public class Client
{
?? public static void main(String[] args) throws Exception
?? {
????? InitialContext ctx = new InitialContext();
????? BookTestRemote book = (BookTestRemote) ctx.lookup
("BookTestBean/remote");
????
??
????? book.test();
?????
????? System.out.println("test successful! ");
?? }
}
三、其他文件
將jboss-EJB-3.0_RC5-PFD\docs\tutorial中的找到的jndi.properties、log4j.xml
、builder.xml等復制到當前工程中，其中builder.xml需要修改。
//builder.xml
<?xml version="1.0"?>
<!--
=======================================================================
-->
<!-- JBoss build file????????????????????????????????????????????????????
? -->
<!--
=======================================================================
-->
<project name="JBoss" default="ejbjar" basedir=".">
?? <property file="../local.properties" />
?? <property environment="env"/>
?? <property name="src.dir" value="${basedir}/src"/>
?? <property name="jboss.home" value="E:/Programming/Servers/jboss-
4.0.3SP1/"/>
?? <property name="jboss.server.config" value="all"/>
?? <property name="build.dir" value="${basedir}/build"/>
?? <property name="build.classes.dir" value="${build.dir}/classes"/>
?? <!-- Build classpath -->
?? <path id="classpath">
????? <!-- So that we can get jndi.properties for InitialContext -->
????? <pathelement location="${basedir}"/>
????? <fileset dir="${jboss.home}/lib">
???????? <include name="**/*.jar"/>
????? </fileset>
????? <fileset dir="${jboss.home}/server/${jboss.server.config}/lib">
???????? <include name="**/*.jar"/>
????? </fileset>
????? <fileset dir="${jboss.home}/server/
${jboss.server.config}/deploy/ejb3.deployer">
???????? <include name="*.jar"/>
????? </fileset>
????? <fileset dir="${jboss.home}/server/
${jboss.server.config}/deploy/jboss-aop-jdk50.deployer">
???????? <include name="*.jar"/>
????? </fileset>
????? <pathelement location="${build.classes.dir}"/>
?? </path>
?? <property name="build.classpath" refid="classpath"/>
?? <!--
=================================================================== -->
?? <!-- Prepares the build directory?????????????????????????????????????
? -->
?? <!--
=================================================================== -->
?? <target name="prepare">
????? <mkdir dir="${build.dir}"/>
????? <mkdir dir="${build.classes.dir}"/>
?? </target>
?? <!--
=================================================================== -->
?? <!-- Compiles the source code?????????????????????????????????????????
? -->
?? <!--
=================================================================== -->
?? <target name="compile" depends="prepare">
????? <javac srcdir="${src.dir}"
???????? destdir="${build.classes.dir}"
???????? debug="on"
???????? deprecation="on"
???????? optimize="off"
???????? includes="**">
???????? <classpath refid="classpath"/>
????? </javac>
?? </target>
?? <target name="ejbjar" depends="compile">
????? <jar jarfile="build/tutorial.jar">
???????? <fileset dir="${build.classes.dir}">
??????????? <include name="**/*.class"/>
???????? </fileset>
????? ? <fileset dir=".">
????? ???? <include name="META-INF/persistence.xml"/>
????? ? </fileset>
????? </jar>
????? <copy file="build/tutorial.jar" todir="${jboss.home}/server/
${jboss.server.config}/deploy"/>
?? </target>
?? <target name="run.stateless" depends="ejbjar">
????? <java classname="ejb.client.stateless.Client" fork="yes" dir=".">
???????? <classpath refid="classpath"/>
????? </java>
?? </target>
?
?<target name="run.stateful" depends="ejbjar">
?????? <java classname="ejb.client.stateful.Client" fork="yes"
dir=".">
????????? <classpath refid="classpath"/>
?????? </java>
?</target>
?
?<target name="run.timer" depends="ejbjar">
?????? <java classname="ejb.client.timer.Client" fork="yes"
dir=".">
????????? <classpath refid="classpath"/>
?????? </java>
?</target>
?
?<target name="run.entity" depends="ejbjar">
??????? <java classname="ejb.client.entity.Client"
fork="yes" dir=".">
?????????? <classpath refid="classpath"/>
??????? </java>
??</target>
?
?? <!--
=================================================================== -->
?? <!-- Cleans up generated stuff????????????????????????????????????????
? -->
?? <!--
=================================================================== -->
?? <target name="clean.db">
????? <delete dir="${jboss.home}/server/
${jboss.server.config}/data/hypersonic"/>
?? </target>
?? <target name="clean">
????? <delete dir="${build.dir}"/>
????? <delete file="${jboss.home}/server/
${jboss.server.config}/deploy/tutorial.jar"/>
?? </target>
</project>
最后，在工程目錄下新建目錄META-INF，在目錄META-INF新建persistence.xml文件
，以下是文件內容：
<?xml version="1.0" encoding="UTF-8"?>
<persistence>
?? <persistence-unit name="test">
????? <jta-data-source>java:/MySqlDS</jta-data-source>
????? <properties>
????? ?<property name="hibernate.dialect"
value="org.hibernate.dialect.MySQLDialect"/>????? ?
??????? <property name="hibernate.hbm2ddl.auto" value="update"/>
????? </properties>
?? </persistence-unit>
</persistence>
四、運行測試
run as->ant build后，選擇運行目標為run.entity->run。
運行結果：
Buildfile: D:\Programs\Java\EclipseWork\EJB3\build.xml
prepare:
compile:
ejbjar:
run.entity:
???? [java] test successful!
BUILD SUCCESSFUL
Total time: 9 seconds
MySQL中select * from book;
id??????? title???????????????????? author
1??????? My first bean book???????? Sebastian
已經成功寫入。
?