Struts Action 控制器

時間 2019-12-11

原文原文鏈接

控制器

即,mvc模型的控制器模型,用於接收數據,傳遞給視圖層,和模型層默認使用execute方法html

查看相關接口

查看com.opensymphony.xwork2下的Action接口文件以下express

/*
 * 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;

}

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大概翻譯一下apache

*
 *得到Apache軟件基金會（ASF）的許可
 *或更多貢獻者許可協議。請參閱NOTICE文件
 *與此工做一塊兒分發以獲取更多信息
 *關於版權全部權。 ASF許可此文件
 *根據Apache許可證2.0版（
 * 「執照」）;除非符合規定，不然您不得使用此文件
 *使用許可證。您能夠在如下位置獲取許可證副本
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 *除非適用法律要求或書面贊成，
 *根據許可證分發的軟件分發在
 *「按原樣」基礎，不提供任何保證或條件
 * KIND，不管是明示的仍是暗示的。請參閱許可證
 *管理權限和限制的特定語言
 *根據許可證。
 * /
package com.opensymphony.xwork2;

/ **
 *全部動做<b>可能</ b>實現此接口，該接口公開<code> execute（）</ code>方法。
 * <p>
 *可是，從XWork 1.1開始，這<b>不</ b>是必需的，僅用於幫助用戶。您能夠自由建立POJO
 *遵照此接口定義的相同合同而不實際實現接口。
 * </ p>
 * /
public interface Action {

    / **
     *行動執行成功。顯示結果
     *查看最終用戶。
     * /
    public static final String SUCCESS =「success」;

    / **
     *行動執行成功但沒有
     *顯示一個視圖。這對於有效的操做頗有用
     *以重定向等其餘方式處理視圖。
     * /
    public static final String NONE =「none」;

    / **
     *行動執行失敗。
     *顯示錯誤視圖，可能會詢問
     *用戶重試輸入數據。
     * /
    public static final String ERROR =「error」;

    / **
     * <p>
     *動做執行須要更多輸入
     *爲了成功。
     *此結果一般用於表格
     *處理行動已經執行
     *提供表單的默認值。該
     *與處理程序關聯的表單應該是
     *向最終用戶顯示。
     * </ p>
     *
     * <p>
     *若是給定輸入，也會使用此結果
     *參數無效，意味着用戶
     *應該嘗試再次提供輸入。
     * </ p>
     * /
    public static final String INPUT =「input」;

    / **
     *行動沒法執行，由於
     *用戶最多未登陸。登陸視圖
     *應該顯示。
     * /
    public static final String LOGIN =「login」;


    / **
     *執行動做的邏輯。
     *
     * @return表示執行邏輯結果的字符串。
     *有關標準結果值的列表，請參閱此界面中的常量。
     * @throws若是發生系統級異常，則拋出異常。
     * <b>注意：</ b>應經過返回來處理應用程序級異常
     *錯誤值，例如<code> Action.ERROR </ code>。
     * /
    public String execute（）拋出異常;

}
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能夠看到,定義了幾個常量一個接口,其中默認執行execute方法,其中幾個常量爲執行結果的常量bash

擴展實現Action接口的ActionSupport類

/**
 * 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
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大概翻譯一下mvc

*爲最多見的操做提供默認實現。
  *有關更多詳細信息，請參閱此類實現的全部接口的文檔。
 */
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因此直接擴展該類便可app

從新擴展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;
    }
}

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能夠在execute中書寫業務邏輯從新更改以下less

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)){
            // 此時返回SUCCESS
            return SUCCESS;
        }else{
            // 其他內容返回error
            return ERROR;
        }
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

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在上方,根據name的值,完成了一個業務邏輯,返回是 or 否jsp

編寫配置文件

<?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>
    <!-- 定義調試 -->
    <constant name="struts.devMode" value="true" />
    <!-- 定義數據包 -->
    <package name="helloworld" extends="struts-default">
        <!-- 定義處理邏輯 name爲指定處理的名稱 class 處理的包文件 method 處理將會調用的方法-->
        <action name="hello"
                class="com.ming.HelloWorldAction"
                method="execute">
            <!-- 成功返回頁面 -->
            <result name="success">/HelloWorld.jsp</result>
            <result name="error">/error.html</result>
        </action>
    </package>
</struts>
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