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EJB 3.0 學習筆記——Entity Bean

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" ?>




< 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 >
???? 
???? 

???? 
???? < 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" ?>





< 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" />

??? 
??? < path? id ="classpath" >
?????? 
?????? < 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" />

??? 
??? 
??? 
??? < target? name ="prepare" >
?????? < mkdir? dir ="${build.dir}" />
?????? < mkdir? dir ="${build.classes.dir}" />
??? </ target >

??? 
??? 
??? 
??? < 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 >
?

??? 
??? 
??? 
??? < 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。

posted on 2006-05-20 22:38 all gone 閱讀(3383) 評論(4) 編輯收藏所屬分類: Java

不行啊，出錯了，大家看看我出錯在哪里
Buildfile: E:\Documents and Settings\myhome\workspace\EJB3Test\src\build.xml
prepare:
compile:
ejbjar:
run.entity:
[java] Exception in thread "main" javax.naming.NameNotFoundException: BookTestBean not bound
[java] at org.jnp.server.NamingServer.getBinding(NamingServer.java:514)
[java] at org.jnp.server.NamingServer.getBinding(NamingServer.java:522)
[java] at org.jnp.server.NamingServer.getObject(NamingServer.java:528)
[java] at org.jnp.server.NamingServer.lookup(NamingServer.java:252)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:585)
[java] at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:294)
[java] at sun.rmi.transport.Transport$1.run(Transport.java:153)
[java] at java.security.AccessController.doPrivileged(Native Method)
[java] at sun.rmi.transport.Transport.serviceCall(Transport.java:149)
[java] at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:466)
[java] at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:707)
[java] at java.lang.Thread.run(Thread.java:595)
[java] at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
[java] at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
[java] at sun.rmi.server.UnicastRef.invoke(Unknown Source)
[java] at org.jnp.server.NamingServer_Stub.lookup(Unknown Source)
[java] at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:610)
[java] at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:572)
[java] at javax.naming.InitialContext.lookup(Unknown Source)
[java] at ejb.bean.entity.Client.main(Client.java:17)
[java] Java Result: 1
BUILD SUCCESSFUL
Total time: 10 seconds
回復更多評論

# re: EJB 3.0 學習筆記——Entity Bean 2006-06-16 19:47 all gone

@frend
你的BookTestBean 沒有部署成功回復更多評論

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# re: EJB 3.0 學習筆記——Entity Bean 2006-05-28 08:06 Richie

# re: EJB 3.0 學習筆記——Entity Bean 2006-05-29 21:32 all gone

# re: EJB 3.0 學習筆記——Entity Bean 2006-06-03 08:30 frend

# re: EJB 3.0 學習筆記——Entity Bean 2006-06-16 19:47 all gone

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