感谢Sun公司的一系列解决方案,EJB3架构起来比SSH简单许多,而且EJB3天生有着强大的分布式部署特性,我个人认为EJB3要比SSH更有吸引力.
很多朋友认为EJB的架构很重量级,我个人认为那只是EJB2的时代,EJB3一样能构建一个很轻量便捷的系统.
首先我们来构建一个最基本的EJB3系统:
系统环境:
1.glassfish3.1
2.eclipse 3.7
3.Derby
不要问我为什么用这些不主流的东西,原因是他们很简单,拿来就能用.特别是derby,很方便的说.
1.glassfish3.1配置,不调优的话基本不用配置.不过一些常用命令还是要记录一下
控制台: http://localhost:4848/
创建域: asadmin create-domain f:
开始域: asadmin start-domain --domaindir f:
关闭域: asadmin stop-domain --domaindir f:
部署war: asadmin deploy f:j2ee.war
反部署: asadmin undeploy f:j2ee.war
运行DB: asadmin start-database --dbhome f:j2db
2.Derby
Derby有两种连接方式,(1)嵌入式,(2)客户端式,区别是嵌入式是独占连接
glassfish默认就有两个数据库连接,分别对应derby的两种连接方式,如果选择timepool,则当我们部署一个EJB的时候DB会同时启动,反之则要手动启动.
3.eclipse
(1)创建一个动态web项目
(2)在src/meta-inf文件夹中创建一个persistence.xml文件,内容如下
<?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="appPU" transaction-type="JTA"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <jta-data-source>jdbc/__TimerPool</jta-data-source> <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode> <validation-mode>NONE</validation-mode> <properties> <property name="eclipselink.target-database" value="Auto" /> <property name="eclipselink.ddl-generation" value="create-tables" /> <property name="eclipselink.show-sql" value="true" /> </properties> </persistence-unit></persistence>
(3)修改web.xml文件如下
<?xml version='1.0' encoding='UTF-8'?><web-app xmlns="http://java.sun.com/xml/ns/javaee" version="3.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name>J2EE</display-name> <context-param> <param-name>javax.faces.STATE_SAVING_METHOD</param-name> <param-value>client</param-value> </context-param> <context-param> <param-name>javax.faces.PROJECT_STAGE</param-name> <param-value>Production</param-value> </context-param> <context-param> <param-name>com.sun.faces.resourceUpdateCheckPeriod</param-name> <param-value>-1</param-value> </context-param> <context-param> <param-name>com.sun.faces.validateXml</param-name> <param-value>true</param-value> </context-param> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>Faces Servlet</servlet-name> <url-pattern>*.jsf</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index</welcome-file> </welcome-file-list> <error-page> <error-code>404</error-code> <location>/error</location> </error-page> <session-config> <session-timeout>10</session-timeout> </session-config> <error-page> <exception-type>javax.faces.application.ViewExpiredException</exception-type> <location>/index</location> </error-page></web-app>
(4)小实例,服务器端,Count.java
/** *@Author : Copper Lau *@Created Date : Feb 19, 2013 *@Modified By : Copper Lau *@Modified Date : Feb 19, 2013 *@Version : 1.0 */package com.copper.test;import javax.faces.bean.ManagedBean;import javax.faces.bean.SessionScoped;@ManagedBean(name = "count")@SessionScopedpublic class Count{ private Integer count = 0; public Integer getCount() { return count; } public void increCount(Integer i) { count = count + i; } public void reset() { this.count = 0; }}(5)Web端
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html"><h:head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <title>Ajax</title></h:head><h:body> <h:form id="form1" prependId="false"> <h:outputScript name="jsf.js" library="javax.faces" target="head" /> <h:outputText id="out1" value="#{count.count}" /> <br /> <!-- Increment the counter on the server, and the client --> <h:commandButton id="button1" value="Count" onclick="jsf.ajax.request(this, event, {execute: this.id, render: 'testId'}); return false;" actionListener="#{count.increCount(234)}" /> <br /> <!-- Resets the counter --> <h:commandButton id="reset" value="reset" onclick="jsf.ajax.request(this, event, {execute:'reset', render: 'out1'}); return false;" actionListener="#{count.reset}" /> <h:panelGrid id="testId"> <div> <h:outputText value="#{count.count}" /> </div> </h:panelGrid> </h:form></h:body></html>配置完成,是不是很简单?
到目前为止,LIB文件夹的第三方包的个数为0.
部署完成后输入http://localhost:8080/J2EE/index.jsf就可以看到结果了.