Action类的三种编写方式（七）
1. Action类就是一个POJO类
什么是POJO类，POJO（Plain Ordinary Java Object）简单的Java对象.简单记：没有继承某个类，没有实现接口，就是POJO的类。2. Action类可以实现Action接口
* Action接口中定义了5个常量，5个常量的值对应的是5个逻辑视图跳转页面（跳转的页面还是需要自己来配置），还定义了一个方法，execute方法。
* 大家需要掌握5个逻辑视图的常量
* SUCCESS -- 成功. * INPUT -- 用于数据表单校验.如果校验失败,跳转INPUT视图. * LOGIN -- 登录. * ERROR -- 错误. * NONE -- 页面不转向.3. Action类可以去继承ActionSupport类（开发中这种方式使用最多）* 设置错误信息
supportAction里面提供了一些属性的方法供我们使用。
举例：
1.POJO
package com.ken.action;public class Demo1Action {/*** execute是默认方法* return null; 不会进行跳转* @return*/public String execute(){System.out.println("Demo1Action就是POJO类...");return null;}
}<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN""http://struts.apache.org/dtds/struts-2.3.dtd">
<struts><package name="default" namespace="/" extends="struts-default"><!-- 配置Action --><action name="hello" class="com.ken.action.HelloAction" method="sayHello"><!-- 配置跳转的页面，路径的写法：在struts2框架中，不管是转发还是重定向都不用写项目名 --><!-- name中的ok叫做逻辑视图名称 --><result name="ok">/demo1/success.jsp</result></action><!-- POJO --><action name="demo1Action" class="com.ken.action.Demo1Action"></action></package>
</struts>
2.实现Action接口
/** Copyright 2002-2007,2009 The Apache Software Foundation.* * Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at* * http://www.apache.org/licenses/LICENSE-2.0* * Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/
package com.opensymphony.xwork2;/*** All actions <b>may</b> implement this interface, which exposes the <code>execute()</code> method.* <p/>* However, as of XWork 1.1, this is <b>not</b> required and is only here to assist users. You are free to create POJOs* that honor the same contract defined by this interface without actually implementing the interface.*/
public interface Action {/*** The action execution was successful. Show result* view to the end user.*/public static final String SUCCESS = "success";/*** The action execution was successful but do not* show a view. This is useful for actions that are* handling the view in another fashion like redirect.*/public static final String NONE = "none";/*** The action execution was a failure.* Show an error view, possibly asking the* user to retry entering data.*/public static final String ERROR = "error";/*** The action execution require more input* in order to succeed.* This result is typically used if a form* handling action has been executed so as* to provide defaults for a form. The* form associated with the handler should be* shown to the end user.* <p/>* This result is also used if the given input* params are invalid, meaning the user* should try providing input again.*/public static final String INPUT = "input";/*** The action could not execute, since the* user most was not logged in. The login view* should be shown.*/public static final String LOGIN = "login";/*** Where the logic of the action is executed.** @return a string representing the logical result of the execution.* See constants in this interface for a list of standard result values.* @throws Exception thrown if a system level exception occurs.* <b>Note:</b> Application level exceptions should be handled by returning* an error value, such as <code>Action.ERROR</code>.*/public String execute() throws Exception;}package com.ken.action;import com.opensymphony.xwork2.Action;/*** 实现Action接口，Action是框架提供的接口*/
public class Demo2Action implements Action {@Overridepublic String execute() throws Exception {System.out.println("实现了Action接口");return SUCCESS;}
}<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN""http://struts.apache.org/dtds/struts-2.3.dtd">
<struts><package name="default" namespace="/" extends="struts-default"><!-- 配置Action --><action name="hello" class="com.ken.action.HelloAction" method="sayHello"><!-- 配置跳转的页面，路径的写法：在struts2框架中，不管是转发还是重定向都不用写项目名 --><!-- name中的ok叫做逻辑视图名称 --><result name="ok">/demo1/success.jsp</result></action><!-- POJO --><action name="demo1Action" class="com.ken.action.Demo1Action"></action><!-- 实现Action接口 --><action name="demo2Action" class="com.ken.action.Demo2Action"><result name="success">/demo1/success.jsp</result></action></package>
</struts>
三、Action类继承ActionSupport
package com.ken.action;import com.opensymphony.xwork2.ActionSupport;/*** 编写Action类继承ActionSupport，ActionSupport已经实现了Action和一些其他的类**/
public class Demo3Action extends ActionSupport {private static final long serialVersionUID = -1796731178213647676L;@Overridepublic String execute() throws Exception {System.out.println("Demo3Action继承了ActionSupport类");return NONE;}
}<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN""http://struts.apache.org/dtds/struts-2.3.dtd">
<struts><package name="default" namespace="/" extends="struts-default"><!-- 配置Action --><action name="hello" class="com.ken.action.HelloAction" method="sayHello"><!-- 配置跳转的页面，路径的写法：在struts2框架中，不管是转发还是重定向都不用写项目名 --><!-- name中的ok叫做逻辑视图名称 --><result name="ok">/demo1/success.jsp</result></action><!-- POJO --><action name="demo1Action" class="com.ken.action.Demo1Action"></action><!-- 实现Action接口 --><action name="demo2Action" class="com.ken.action.Demo2Action"><result name="success">/demo1/success.jsp</result></action><!-- Action类继承ActionSupport --><action name="demo3Action" class="com.ken.action.Demo3Action"></action></package>
</struts>
源码下载
