利用java反射機制實現自動調用類的簡單方法

1. 新建TestServlet類

package com.yanek.test;import java.io.IOException;import java.lang.reflect.Method;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class TestServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 獲取類的全路徑以及名稱String className = request.getParameter("className"); // 獲取方法名String methodName = request.getParameter("method"); try { // 獲取class文件Class<?> t_class = Class.forName(className); // 獲取該類所需求的方法Method method = t_class.getDeclaredMethod(methodName, HttpServletRequest.class, HttpServletResponse.class); method.invoke(t_class.newInstance(), request, response);// 方法的實現} catch (Exception e) { e.printStackTrace(); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}

2. 建立需要自動調用的類

package com.yanek.test;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class Test { /** * @param args */ public static void main(String[] args) { System.out.println("hello world !"); } public void test(HttpServletRequest request, HttpServletResponse response) { System.out.println("hello"); System.out.println(request.getParameter("username")); }}

3. web.xml配置

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <description>Test</description> <display-name>Test</display-name> <servlet-name>Test</servlet-name> <servlet-class>com.yanek.test.TestServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Test</servlet-name> <url-pattern>/Test</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <login-config> <auth-method>BASIC</auth-method> </login-config></web-app>

4. 啟動服務器訪問:

http://127.0.0.1:8081/TestPrj/Test?className=com.yanek.test.Test&method=test&username=aspboy

控制台輸出:

hello

aspboy

說明: 類com.yanek.test.Test類的方法public void test(HttpServletRequest request, HttpServletResponse response) 被執行了.

反射機制是java中的重要功能,在框架設計中大量使用.

測試環境: tomcat6.0

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