利用java反射机制实现自动调用类的简单方法

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