William's 秘密基地: [Struts2] 自訂攔截器 creating own interceptor

2015年4月22日星期三

[Struts2] 自訂攔截器 creating own interceptor

範例原始碼下載：http://goo.gl/mzuXt6 使用 Intellij IDEA

Action 的生命週期

由此看出，攔截器式運作在 Action 之前

自訂攔截器流程：

1.練立一個類別 implements com.opensymphony.xwork2.interceptor.Interceptor

2.implement 當中的 intercept(ActionInvocation invocation) 方法

3.在 struts.xml(struts 配置檔)中配置自訂的 interceptor

4.依照需求配置到所要運作的 action 當中

簡單做一個範例畫面如下：

點擊測試之後，將input field 中的值導到歡迎頁面中

=== Action ===

package test.actions;

import com.opensymphony.xwork2.ActionSupport;


public class HelloWorld extends ActionSupport {
    private String msg;

    @Override
    public String execute() throws Exception {
        System.out.println("HelloWorld Action execute Method");
        return SUCCESS;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

=== Interceptor ===

package test.interceptors;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

/**
 * Created by Hsu on 2015/4/22.
 */
public class SaysomethingInterceptor implements Interceptor {
    @Override
    public void destroy() {
        System.out.println("SaysomethingInterceptor is destory");
    }

    @Override
    public void init() {
        System.out.println("SaysomethingInterceptor is initial");
    }

    @Override
    public String intercept(ActionInvocation actionInvocation) throws Exception {
        System.out.println("SaysomethingInterceptor before invoke");
        // Start execute Action
        String result = actionInvocation.invoke();
        System.out.println("SaysomethingInterceptor after invoke");
        return result;
    }
}

在 SaysomethingInterceptor 中，我們只單純加了幾個 sysout，以便觀察運作流程

String result = actionInvocation.invoke();
return result;

actionInvocation.invoke(); 主要就是執行 Action 中的流程

=== Struts.xml ===

<?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>
    <constant name="struts.devMode" value="true"/>
    <constant name="struts.locale" value="zh_TW"/>
    <!-- 定義系統預設編碼集 -->
    <constant name="struts.i18n.encoding" value="UTF-8"/>

    <package name="test" extends="struts-default">
        <interceptors>
            <interceptor name="Saysomething" class="test.interceptors.SaysomethingInterceptor"/>

            <interceptor-stack name="myStack">
                <interceptor-ref name="Saysomething"/>
                <interceptor-ref name="defaultStack"/>
            </interceptor-stack>
        </interceptors>

        <action name="HelloAction" class="test.actions.HelloWorld">
            <interceptor-ref name="myStack"/>
            <result name="success">/welcome.jsp</result>
        </action>
    </package>
</struts>

上面的配置，主要就是宣告自訂攔截器，並將該攔截器配置到我們所想要執行的 Action 中

Web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         id="WebApp_ID" version="2.5">
    <display-name>Archetype Created Web Application</display-name>

    <filter>
        <filter-name>struts2</filter-name>
        <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <welcome-file-list>
        <welcome-file>/index.jsp</welcome-file>
    </welcome-file-list>
</web-app>