利用java反射机制实现自动调用类的方法

 1. 新建TestServlet类

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 {
  // 获取类的全路径以及名称
  String className = request.getParameter("className");
  // 获取方法名
  String methodName = request.getParameter("method");
  try {
   // 获取class文件
   Class<?> t_class = Class.forName(className);
   // 获取该类所需求的方法
   Method method = t_class.getDeclaredMethod(methodName,
     HttpServletRequest.class, HttpServletResponse.class);
   method.invoke(t_class.newInstance(), request, response);// 方法的实现
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doGet(request, response);
 }

}

 

2. 建立需要自动调用的类

 

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. 启动服务器访问:

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

 

控制台输出:

hello
aspboy

 

说明: 类com.yanek.test.Test类的 方法 public void test(HttpServletRequest request, HttpServletResponse response) 被执行了.

反射机制是java中的重要功能,在框架设计中大量使用.

测试环境: tomcat6.0