baseServlet的工具类

功能过多.servlet管理不方便,为了减少servlet的数量,便于管理维护,可以使用工具类来做:

baseServlet的工具类:

package com.wangshi.servlet;

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;

/**
 * @author wanghaihcuan
 *baseServlet的工具类(继承httpServlet)
 *没有的话去父类里面找,一级一级找,找到为止
 */
public class BaseServlet extends HttpServlet {
	
	@Override
	public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		System.out.println("这里是 service.......");
		
		//获取客户端 提交 到服务器端的 method 对应的值
		String method = request.getParameter("method");
		
		//定义变量,存放功能执行完毕之后要转发的路径
		String path = null;
		
		//获取当前字节码对象(servletDemo02.class 在内存中的对象)
		Class clazz = this.getClass();
		
		try {
			//获取clazz上名称为method的方法
			Method method1 = clazz.getMethod(method,HttpServletRequest.class ,HttpServletResponse.class );
			if(null != method1){
				//调用找到的方法
				path=(String)  method1.invoke(this, request,response);
			}
			
			if(null != path){
				//服务端的转发
				request.getRequestDispatcher(path).forward(request, response);
			}
			
		} catch (Exception e) {
			e.printStackTrace();
		}	
	}
  
}

servlet1.0版本:

package com.wangshi.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;

/**servlet 1.0版本
 * @author wanghaichaun
 *客户端向服务器提交表单产生一个键值对method, 目的是减少servlet数量
 *如果 功能过多,不易维护,可用反射来做
 */
public class ServletDemo01 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		//要转发的路径[因为要跳转的是路径,只不过是跳转不同,所以抽取出来]
		String path = null;
		
		//获取客户端提交到服务器的method 对应的值
		String method = request.getParameter("method");
		//通过判断method中不同的内容来决定 本次功能
		if("addStu".equals(method)){
			path=addStu(request, response);
			//System.out.println("添加学生......");
		}else if ("delStu".equals(method)) {
			path=delStu(request, response);
			//System.out.println("删除学生......");
		}else if ("checkStu".equals(method)) {
			path=checkStu(request, response);
			//System.out.println("检查学生......");
		}
		
		//判断它是否为空,服务端的 统一的 转发
		if( null != path){
			request.getRequestDispatcher(path).forward(request, response);
		}
	}


	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
	
	protected String addStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("添加学生......");
		return "/test.html";
	}
	protected String delStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("删除学生......");
		return "/test.html";
	}
	protected String checkStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setCharacterEncoding("utf-8");
		System.out.println("检查学生......");
		response.getWriter().println("我在看着你看着你");
		return null;
}
}

servlet2.0版本:反射

package com.wangshi.servlet;

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;

/**
 * @author wanghaichuan
 *使用 反射 来减少servlet数量
 */
public class ServletDemo02 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
	
		//获取客户端 提交 到服务器端的 method 对应的值
		String method = request.getParameter("method");
		
		//定义变量,存放功能执行完毕之后要转发的路径
		String path = null;
		
		//获取当前字节码对象(servletDemo02.class 在内存中的对象)
		Class clazz = this.getClass();
		
		try {
			//获取clazz上名称为method的方法
			Method method1 = clazz.getMethod(method,HttpServletRequest.class ,HttpServletResponse.class );
			if(null != method1){
				//调用找到的方法
				path=(String)  method1.invoke(this, request,response);
			}
			
			if(null != path){
				//服务端的转发
				request.getRequestDispatcher(path).forward(request, response);
			}
			
		} catch (Exception e) {
			e.printStackTrace();
		}	
	}
	
	public String addStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
			System.out.println("添加学生");
			return "/test.html";
	}
	public String delStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("删除学生");
		return "/test.html";
	}
	public String checkStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("检查学生");
		response.setCharacterEncoding("utf-8");
		response.getWriter().println("呦呦呦,等你哦");
		return null;
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

jsp页面提交方式:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script  type="text/javascript" src="js/jquery-1.11.3.min.js"></script>
<script >
	
	function fn(){//post方法数据,登录验证检查
		$.post("/BaseServlet/ServletDemo03",{"method":"checkStu","user":"tom"},function(data){
			alert(data);
		}/* ,"json" */);
	}
</script>
</head>

<body>
	<!-- 从客户端发起请求到服务端的功能,如下 -->
	<!-- 用表单提交 -->
	<form action="/BaseServlet/ServletDemo03?method=addStu" method="post">
		用户名:<input type="text" name="username" /><br>
		密码:<input type="password" name="password" /><br>
		<input type="submit" value="提交"/>
	</form><br>
	
	<!-- 链接提交界面 -->
	<a href="/BaseServlet/ServletDemo03?method=delStu">删除学生</a><br>
	
	<!-- ajax按钮提交 -->
	<button onclick="fn()">按钮</button>

</body>
</html>