servlet+Java反射机制实现mvc模式

一，servlet基类，BaseController类继承HttpServlet，实现了doGET和doPost方法，至关于springmvc的dispacterservlet,咱们只须要在web.xml注册一个BaseController便可。 BaseController.ava package com.easygo.controller; import java.io.IOException; import java.util.Properties; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class BaseController extends HttpServlet { /** * */
    private static final long serialVersionUID = 1L; //调用properties 配置文件
    private  Properties  properties=new Properties(); //字符编码集合
    private String charset="utf-8"; @Override public void init(ServletConfig config) throws ServletException { //获取初始化的 参数 key value
     String  configname=config.getInitParameter("configname"); try { //自动加载配置文件
        properties.load(this.getClass().getClassLoader().getResourceAsStream(configname)); //经过配置文件获取到字符编码集
      String tmp=    properties.getProperty("charset"); if(tmp!=null){ charset=tmp; } } catch (IOException e) { e.printStackTrace(); System.out.println("读取失败！"); } } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { try { //设置字符编码集
 req.setCharacterEncoding(charset); resp.setCharacterEncoding(charset); //获取到 uri
        String act= req.getRequestURI(); // System.out.println(act); // /MVCController/ user .do // user --- 找到Config文件的com.uplooking.action.UserAction
        act=act.substring(act.lastIndexOf("/")+1,act.lastIndexOf(".do")); // 获取类路径 System.out.println(act); 
        String classPath= properties.getProperty(act); // System.out.println(classPath);
        
        if(classPath==null||classPath.equals("")){ resp.setContentType("text/html"); resp.getWriter().println("没有您要访问的路径！"); return; } //进行反射调用 
        Class    iActionClass =Class.forName(classPath); //反向实例
        IAction   iAction=(IAction) iActionClass.newInstance(); //交给 子方法进行处理 处理完以后 只要 返回 String request response //封装返回值 
        String result= iAction.execute(req, resp); System.out.println("返回值="+result); //有返回值的时候
        if(result!=null&&!"".equals(result)){ /* 1 默认转发 return "index.jsp"; 2 重定向 return "@red_index.jsp" 3json return "@json_{XXXXXX}"*/
            if(result.contains("@red_")){ //重定向
                resp.sendRedirect(result.split("_")[1]); }else if(result.contains("@json_")){ resp.setContentType("text/html"); resp.getWriter().println(result.split("_")[1]); resp.getWriter().close(); }else{ req.getRequestDispatcher(result).forward(req, resp); } }else{ //没有返回值的时候
            resp.setContentType("text/html"); resp.getWriter().println("没有返回值！"); return; } } catch (ClassNotFoundException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } catch (InstantiationException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } } --------------------------------------------------------------------------------------------------------------------------------- web.xml配置： <?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>MVCController</display-name>
  
  
  <servlet>
         <servlet-name>BaseController</servlet-name>
           <servlet-class>com.easygo.controller.BaseController</servlet-class>
         <init-param>
            <param-name>configname</param-name>
            <param-value>ActionConfig.properties</param-value>
         </init-param>
         <load-on-startup>0</load-on-startup>
  </servlet>
  
  <servlet-mapping>
     <servlet-name>BaseController</servlet-name>
     <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  
  
  
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>  --------------------------------------------------------------------------------------------------------------------------------- IAction接口,Action类实现IAction接口 package com.easygo.action; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.easygo.controller.IAction; public class BookAction implements IAction{ @Override public String execute(HttpServletRequest req, HttpServletResponse resp) { System.out.println("BookAction"); return "@red_index.jsp"; } }  --------------------------------------------------------------------------------------------------------------------------------- ActionConfig.properties，key表明URL请求的名称，以.do为后缀，value是改类的全类名，用于反射。 charset=utf-8 #user.do user=com.easygo.action.UserAction #book.do book=com.easygo.action.BookAction json=com.easygo.action.JsonAction  --------------------------------------------------------------------------------------------------------------------------------- UserAction.java类，原理与springMVC的RequestMapping注解下的方法同样，用于数据返回和页面跳转。 package com.easygo.action; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.easygo.controller.IAction; public class UserAction  implements IAction { @Override public String execute(HttpServletRequest req, HttpServletResponse resp) { System.out.println("UserAction"); return "index.jsp"; } /* * BaseController.java 把 HttpServletRequest req, HttpServletResponse resp * 经过反射 交给指定的类的 方法去处理 * * | * | * * 处理逻辑方法 * * 处理完以后 转发 * 重定向 * json * * String X指向 _ 访问的页面/数据 * | * | * | * 这个String --BaseController * * @Override public String execute(HttpServletRequest req, HttpServletResponse resp) { // TODO Auto-generated method stub return null; } */ }  --------------------------------------------------------------------------------------------------------------------------------- JsonAction.java用于json数据的返回。 package com.easygo.action; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.easygo.controller.IAction; public class JsonAction implements IAction{ @Override public String execute(HttpServletRequest req, HttpServletResponse resp) { System.out.println("JsonAction"); return "@json_{asdsadsadsadsadad}"; } }  --------------------------------------------------------------------------------------------------------------------------------- index.jsp <%@ 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>
</head>
<body> index.jsp </body>
</html>  --------------------------------------------------------------------------------------------------------------------------------- indexX.jsp <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<a href="user.do">user.do</a>
</body>
</html>  --------------------------------------------------------------------------------------------------------------------------------- 测试： 运行indexX.jsp（tomcat8.0） 点击：user.do直接跳转到index.jsp URL:http://localhost:8088/MVCController/user.do
具体代码：连接: https://pan.baidu.com/s/1spMCZ0hAn_FLAZb1OG5-Pw 密码: 77zi