Struts Action 控制器

Posted 2021-04-28 小明菜市场

控制器

即,mvc模型的控制器模型,用于接收数据,传递给视图层,和模型层 默认使用execute方法

查看相关接口

查看com.opensymphony.xwork2下的Action接口 文件如下

/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. * </p> */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";
 /** * <p> * 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> * * <p> * This result is also used if the given input * params are invalid, meaning the user * should try providing input again. * </p> */ 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;
}

大概翻译一下

 * *获得Apache软件基金会（ASF）的许可 *或更多贡献者许可协议。请参阅NOTICE文件 *与此工作一起分发以获取更多信息 *关于版权所有权。 ASF许可此文件 *根据Apache许可证2.0版（ * “执照”）;除非符合规定，否则您不得使用此文件 *使用许可证。您可以在以下位置获取许可证副本 * * http://www.apache.org/licenses/LICENSE-2.0 * *除非适用法律要求或书面同意， *根据许可证分发的软件分发在 *“按原样”基础，不提供任何保证或条件 * KIND，无论是明示的还是暗示的。请参阅许可证 *管理权限和限制的特定语言 *根据许可证。 * /package com.opensymphony.xwork2;
/ ** *所有动作<b>可能</ b>实现此接口，该接口公开<code> execute（）</ code>方法。 * <p> *但是，从XWork 1.1开始，这<b>不</ b>是必需的，仅用于帮助用户。您可以自由创建POJO *遵守此接口定义的相同合同而不实际实现接口。 * </ p> * /public interface Action {
 / ** *行动执行成功。显示结果 *查看最终用户。 * / public static final String SUCCESS =“success”;
 / ** *行动执行成功但没有 *显示一个视图。这对于有效的操作很有用 *以重定向等其他方式处理视图。 * / public static final String NONE =“none”;
 / ** *行动执行失败。 *显示错误视图，可能会询问 *用户重试输入数据。 * / public static final String ERROR =“error”;
 / ** * <p> *动作执行需要更多输入 *为了成功。 *此结果通常用于表格 *处理行动已经执行 *提供表单的默认值。该 *与处理程序关联的表单应该是 *向最终用户显示。 * </ p> * * <p> *如果给定输入，也会使用此结果 *参数无效，意味着用户 *应该尝试再次提供输入。 * </ p> * / public static final String INPUT =“input”;
 / ** *行动无法执行，因为 *用户最多未登录。登录视图 *应该显示。 * / public static final String LOGIN =“login”;

 / ** *执行动作的逻辑。 * * @return表示执行逻辑结果的字符串。 *有关标准结果值的列表，请参阅此界面中的常量。 * @throws如果发生系统级异常，则抛出异常。 * <b>注意：</ b>应通过返回来处理应用程序级异常 *错误值，例如<code> Action.ERROR </ code>。 * / public String execute（）抛出异常;
}

可以看到,定义了几个常量一个接口,其中默认执行execute方法,其中几个常量为执行结果的常量

扩展实现Action接口的ActionSupport类

/** * Provides a default implementation for the most common actions. * See the documentation for all the interfaces this class implements for more detailed information. */public class ActionSupport implements Action, Validateable, ValidationAware, TextProvider, LocaleProvider, Serializable

大概翻译一下

*为最常见的操作提供默认实现。 *有关更多详细信息，请参阅此类实现的所有接口的文档。 */

所以直接扩展该类即可

重新扩展HelloWorldAction

package com.ming;
import com.opensymphony.xwork2.ActionSupport;
public class HelloWorldAction extends ActionSupport { private String name;
 @Override public String execute() throws Exception { return "success"; }
 public String getName() { return name; }
 public void setName(String name) { this.name = name; }}

可以在execute中书写业务逻辑 重新更改如下

package com.ming;
import com.opensymphony.xwork2.ActionSupport;
public class HelloWorldAction extends ActionSupport { private String name;
 @Override public String execute() throws Exception { if(SUCCESS.equals(name)){ // 此时返回SUCCESS return SUCCESS; }else{ // 其余内容返回error return ERROR; } }
 public String getName() { return name; }
 public void setName(String name) { this.name = name; }}

在上方,根据name的值,完成了一个业务逻辑,返回是 or 否

编写配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.5//EN" "http://struts.apache.org/dtds/struts-2.5.dtd">
<struts> <!-- 定义调试 --> <constant name="struts.devMode" value="true" /> <!-- 定义数据包 --> <package name="helloworld" extends="struts-default"> <!-- 定义处理逻辑 name为指定处理的名称 class 处理的包文件 method 处理将会调用的方法--> <action name="hello" class="com.ming.HelloWorldAction" method="execute"> <!-- 成功返回页面 --> <result name="success">/HelloWorld.jsp</result> <result name="error">/error.html</result> </action> </package></struts>

效果如下