JavaWeb 專案啟動時,後臺開啟一個執行緒的方法
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監聽(Listener)
首先,我們建立一個監聽的類,繼承ServletContextListener,如下:-
package com.wxp.thread;
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import javax.servlet.ServletContextEvent;
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import javax.servlet.ServletContextListener;
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/**
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* Listener的方式在後臺執行一執行緒
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*
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* @author Champion.Wong
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*
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*/
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publicclass MyListener implements ServletContextListener {
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private MyThread myThread;
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publicvoid contextDestroyed(ServletContextEvent e) {
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if (myThread != null && myThread.isInterrupted()) {
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myThread.interrupt();
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}
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}
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publicvoid contextInitialized(ServletContextEvent e) {
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String str = null;
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if (str == null && myThread == null) {
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myThread = new MyThread();
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myThread.start(); // servlet 上下文初始化時啟動 socket
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}
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}
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}
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/**
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* 自定義一個 Class 執行緒類繼承自執行緒類,重寫 run() 方法,用於從後臺獲取並處理資料
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*
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* @author Champion.Wong
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*
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*/
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class MyThread extends Thread {
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publicvoid run() {
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while (!this.isInterrupted()) {// 執行緒未中斷執行迴圈
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try {
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Thread.sleep(2000); //每隔2000ms執行一次
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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// ------------------ 開始執行 ---------------------------
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System.out.println("____FUCK TIME:" + System.currentTimeMillis());
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}
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}
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}
然後,在web.xml中配置如下:-
<listener>
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<listener-class>com.wxp.thread.MyListener</listener-class>
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</listener>
OK,啟動專案,我們可以在控制檯看到隔時間段輸出的文字內容。
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使用Servlet,在專案啟動的時候啟動它。
首先,建立一個Servlet,繼承HttpServlet-
package com.wxp.thread;
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import java.io.IOException;
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import javax.servlet.ServletException;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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import com.ite.common.Constants;
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publicclass MyServlet extends HttpServlet{
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privatestaticfinallong serialVersionUID = 1L;
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private MyThread1 myThread1;
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public MyServlet(){
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}
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publicvoid init(){
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String str = null;
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if (str == null && myThread1 == null) {
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myThread1 = new MyThread1();
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myThread1.start(); // servlet 上下文初始化時啟動 socket
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}
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}
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publicvoid doGet(HttpServletRequest httpservletrequest, HttpServletResponse httpservletresponse)
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throws ServletException, IOException{
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}
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publicvoid destory(){
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if (myThread1 != null && myThread1.isInterrupted()) {
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myThread1.interrupt();
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}
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}
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}
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/**
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* 自定義一個 Class 執行緒類繼承自執行緒類,重寫 run() 方法,用於從後臺獲取並處理資料
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*
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* @author Champion.Wong
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*
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*/
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class MyThread1 extends Thread {
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publicvoid run() {
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while (!this.isInterrupted()) {// 執行緒未中斷執行迴圈
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try {
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Thread.sleep(2000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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// ------------------ 開始執行 ---------------------------
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System.out.println("____FUCK TIME:" + System.currentTimeMillis());
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}
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}
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}
然後,在web.xml中配置
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<!-- LISTENER FOR THREAD -->
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<servlet>
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<servlet-name>MyListener</servlet-name>
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<servlet-class>com.ite.wxp.MyServlet</servlet-class>
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<load-on-startup>9</load-on-startup><!-- 數字越小,啟動的優先順序越高,必須大於0 -->
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</servlet>
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<servlet-mapping>
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<servlet-name>MyListener</servlet-name>
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<url-pattern>/test</url-pattern>
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</servlet-mapping>
OK。啟動專案,依然可以看到如圖所示:
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