[原创]java WEB学习笔记22：MVC案例完整实践(part 3)---多个请求对应一个Servlet解析...-白红宇

[原创]java WEB学习笔记22：MVC案例完整实践(part 3)---多个请求对应一个Servlet解析...

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发布时间：2019-06-14

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多个请求对应一个Servlet解析

如果我们每一个请求对应一个Servelt，这样的话，代码就显得比较臃肿，最主要的是，也不方便系代码的管理和优化

方式一：

　　1. 思路：对于每一个页面请求我们设置成一个对应的方法，并且为请求的url设置相应的method参数，servlet-mapping 为 @WebServlet("/customerServlet") ,而在Servlet 中通过获取 method 参数不同的取值，通过一个switch 语句选择不同的方法，同时调用不同的方法。

　　2. 代码：test1.jsp , CustomerServlet1.java

　　test.jsp

1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2     pageEncoding="UTF-8"%> 3  4  5  6 
      7 测试 8  9 10         11             Add112             
13         14             Query115             
16         17             Delete118             
19             
20             
21             22             23         24 25

　　CustomerServlet1.java

1 package com.jason.mvcapp.servlet; 2  3 import java.io.IOException; 4 import javax.servlet.ServletException; 5 import javax.servlet.annotation.WebServlet; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 /**11  * Servlet implementation class CustomerServlet12  */13 @WebServlet("/customerServlet")14 public class CustomerServlet1 extends HttpServlet {15     private static final long serialVersionUID = 1L;16 17     /**18      * 19      */20     protected void doGet(HttpServletRequest request,21             HttpServletResponse response) throws ServletException, IOException {22         doPost(request, response);23     }24 25     protected void doPost(HttpServletRequest request,26             HttpServletResponse response) throws ServletException, IOException {27 28         String method = request.getParameter("method");29 30         switch (method) {31         case "add":32             add(request, response);33             break;34         case "query":35             query(request, response);36             break;37         case "delete":38             delete(request, response);39             break;40         }41 42     }43 44     private void delete(HttpServletRequest request, HttpServletResponse response)45             throws ServletException, IOException {46         System.out.println("delete");47 48     }49 50     private void query(HttpServletRequest request, HttpServletResponse response)51             throws ServletException, IOException {52         System.out.println("query");53 54     }55 56     private void add(HttpServletRequest request, HttpServletResponse response)57             throws ServletException, IOException {58         System.out.println("add");59     }60 61 }

方法二：

　　1. 思路：将所有的请求都设置成 方法名.do, 而将 servlet-mapping 为 @WebServlet("*.do")，即响应所有以 .do 结尾的请求.在Servlet中通过反射，获取运行时类，之后invoke() 调用方法

　　2.代码：test2.jsp , CustomerServlet2.java

　　test2.jsp

1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2     pageEncoding="UTF-8"%> 3  4  5  6 
      7 测试2 8  9 10 11             Add212             
13         14             Query215             
16         17             Delete218             
19             20             Update221             
22             23             Edite224             
25             26 27 28

　　CustomerServlet2.java

1 package com.jason.mvcapp.servlet; 2  3 import java.io.IOException; 4 import java.lang.reflect.InvocationTargetException; 5 import java.lang.reflect.Method; 6  7 import javax.servlet.ServletException; 8 import javax.servlet.annotation.WebServlet; 9 import javax.servlet.http.HttpServlet;10 import javax.servlet.http.HttpServletRequest;11 import javax.servlet.http.HttpServletResponse;12 13 /**14  * Servlet implementation class CustomerServlet215  */16 @WebServlet("*.do")17 public class CustomerServlet2 extends HttpServlet {18     private static final long serialVersionUID = 1L;19 20     protected void doGet(HttpServletRequest request,21             HttpServletResponse response) throws ServletException, IOException {22         doPost(request, response);23     }24 25     protected void doPost(HttpServletRequest request,26             HttpServletResponse response) throws ServletException, IOException {27         //1.获取servletPath：/add.do 或者 query.do28         String serveltPath = request.getServletPath();29         30          System.out.println(serveltPath);31         //2.去除/ 和 .do 得到对应的方法，如 add  query32         String methodName = serveltPath.substring(1);33         methodName = methodName.substring(0, methodName.length() - 3);34         // System.out.println(methodName);35 36         try {37             //3.利用反射获取methodName对应的方法38             Method method = getClass().getDeclaredMethod(methodName,39                     HttpServletRequest.class, HttpServletResponse.class);40             41             //4.利用反射调用方法42             method.invoke(this, request, response);43         } catch (Exception e) {44 45             e.printStackTrace();46         }47     }48 49     50     51     private void update(HttpServletRequest request, HttpServletResponse response)52             throws ServletException, IOException {53         System.out.println("update");54 55     }56 57     private void editeCustomer(HttpServletRequest request,58             HttpServletResponse response) throws ServletException, IOException {59         System.out.println("edit");60 61     }62 63     private void deleteCustomer(HttpServletRequest request,64             HttpServletResponse response) throws ServletException, IOException {65         System.out.println("delete");66 67     }68 69     private void query(HttpServletRequest request, HttpServletResponse response)70             throws ServletException, IOException {71         System.out.println("query");72 73     }74 75     private void addCustomer(HttpServletRequest request,76             HttpServletResponse response) throws ServletException, IOException {77         System.out.println("add");78     }79 80 }

总结：

　　1）理解由方式一过度到方法二;

　　2）理解反射获取当前类，获取提交的方法，及解析，调用相应的方法;

转载于:https://www.cnblogs.com/jasonHome/p/5528628.html