自定义MVC实现登录案例

MVC框架： MVC全名是Model View Controller，是模型(model)-视图(view)-控制器(controller)的缩写，一种软件设计典范，用一种业务逻辑、数据、界面显示分离的方法组织代码，将业务逻辑聚集到一个部件里面，在改进和个性化定制界面及用户交互的同时，不需要重新编写业务逻辑。MVC被独特的发展起来用于映射传统的输入、处理和输出功能在一个逻辑的图形化用户界面的结构中。

我们今天自己定义的MVC框架是简单模仿struts2的

然后我们会用到两个常用的技能点，一个是使用dom4j解析xml文件，还有一个是java反射机制。

案例架构：

1.导入依赖jar包：

 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <parent>
         <artifactId>01MyBatis</artifactId>
         <groupId>cn.happy</groupId>
         <version>1.0-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
     <artifactId>12CustomMVC</artifactId>
     <packaging>war</packaging>
     <name>12CustomMVC Maven Webapp</name>
     <url>http://maven.apache.org</url>
     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.3</version>
             <scope>test</scope>
         </dependency>

         <!-- https://mvnrepository.com/artifact/dom4j/dom4j -->
         <dependency>
             <groupId>dom4j</groupId>
             <artifactId>dom4j</artifactId>
             <version>1.6.1</version>
         </dependency>

         <!--ServletAPI-->
         <dependency>
             <groupId>javaee</groupId>
             <artifactId>javaee-api</artifactId>
             <version>5</version>
         </dependency>
     </dependencies>
     <build>
         <resources>
             <resource>
                 <directory>src/main/java</directory>
                 <includes>
                     <include>**/*.*</include>
                 </includes>
             </resource>
         </resources>
     </build>
 </project>

2..定义自己的dtd约束文件和配置信息：

 <?xml version='1.0' encoding='UTF-8'?>
 <!DOCTYPE myframe[
         <!ELEMENT myframe (actions)>
         <!ELEMENT actions (action*)>
         <!ELEMENT action (result*)>
         <!ATTLIST action
                 name CDATA #REQUIRED
                 class CDATA #REQUIRED>
         <!ELEMENT result (#PCDATA)>
         <!ATTLIST result
                 name CDATA #IMPLIED
                 redirect (true|false) "false">
         ]>
 <myframe>
     <actions>
         <action name="login" class="cn.curry.action.LoginAction">
             <result name="success">/success.jsp</result>
             <result name="login">login.jsp</result>
         </action>
     </actions>
 </myframe>

3.分层搭建

Action：

Action  自己定义的结果集和执行方法 ：

 package cn.curry.action;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 /**
  * Created by Administrator on 2018/3/4.
  */
 public interface Action {
     //定义字符串常量
     public static final String SUCCESS="success";
     public static final String NONE="none";
     public static final String ERROR="error";
     public static final String INPUT="input";
     public static final String LOGIN="login";
     //准备一个方法，用于获取数据
     public String execute(HttpServletRequest request, HttpServletResponse response)throws Exception;
 }

定义一个ActionMapping用来存放Action节点

 package cn.curry.action;

 import java.util.HashMap;
 import java.util.Map;

 /**
  * Created by Administrator on 2018/3/4.
  */
 public class ActionMapping {
     private String name;
     private String className;
     private Map<String,String> map=new HashMap<String, String>();

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public String getClassName() {
         return className;
     }

     public void setClassName(String className) {
         this.className = className;
     }

     public String getValue(String key) {
         return map.get(key);
     }

     public void addToMap(String key,String value) {
         map.put(key,value);
     }
 }

定义ActionManager  通过类名用反射机制获取对象

 package cn.curry.action;

 /**
  * Created by Administrator on 2018/3/4.
  */
 public class ActionManager {
     public static Action getActionClass(String className) throws Exception{
         Class clazz=null;
         Action action=null;
         clazz=Thread.currentThread().getContextClassLoader().loadClass(className);
         if (clazz==null){
             clazz=Class.forName(className);
         }
         if (action==null){
             action=(Action) clazz.newInstance();
         }
         return action;
     }
 }

ActionMappingManager  通过dom4j读取xml

 package cn.curry.action;

 import org.dom4j.Document;
 import org.dom4j.Element;
 import org.dom4j.io.SAXReader;

 import java.io.InputStream;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;

 /**
  * Created by Administrator on 2018/3/4.
  */
 public class ActionMappingManager {
     private Map<String,ActionMapping> map=new HashMap<String, ActionMapping>();

     public  ActionMapping getValue(String key) {
         return map.get(key);
     }

     public void addToMaps(String key,ActionMapping value) {
         map.put(key,value);
     }

     public ActionMappingManager(String [] files)throws Exception{
         for (String item:files){
             init(item);
         }
     }
     public void init(String path)throws Exception{
         InputStream is=this.getClass().getResourceAsStream("/"+path);
         Document doc=new SAXReader().read(is);
         Element root=doc.getRootElement();
         Element actions=(Element)root.elements("actions").iterator().next();
         for (Iterator<Element> action = actions.elementIterator("action"); action.hasNext();){
             Element actionnext=action.next();
             ActionMapping am=new ActionMapping();
             am.setName(actionnext.attributeValue("name"));
             am.setClassName(actionnext.attributeValue("class"));
             for (Iterator<Element> result=actionnext.elementIterator("result");result.hasNext();){
                 Element resultnext=result.next();
                 String name=resultnext.attributeValue("name");
                 String value=resultnext.getText();
                 if (name==null||"".equals(name)){
                     name="success";
                 }
                 am.addToMap(name,value);
             }
             map.put(am.getName(),am);
         }
     }
 }

接下来我们定义一个Servlet来获取请求LoginServlet 主通过获取的请求找到Framework.xml

 package cn.curry.servlet;

 import cn.curry.action.Action;
 import cn.curry.action.ActionManager;
 import cn.curry.action.ActionMapping;
 import cn.curry.action.ActionMappingManager;

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

 /**
  * Created by Administrator on 2018/3/4.
  */
 public class LoginServlet extends HttpServlet {
     private ActionMappingManager manager=null;
     private String getClassName(HttpServletRequest request){
         String uri=request.getRequestURI();
         System.out.println(uri+"        uri");
         String context=request.getContextPath();
         System.out.println(context+"             context");
         String result=uri.substring(context.length());
         System.out.println(result+"              result");
         return result.substring(1,result.lastIndexOf("."));
     }

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         String key=getClassName(request);
         System.out.println(key+"           key");
         try {
             ActionMapping actionMapping=manager.getValue(key);
             System.out.println(actionMapping.getClassName()+"            classname");
             Action action= ActionManager.getActionClass(actionMapping.getClassName());
             String result=action.execute(request,response);
             System.out.println(result+"                   result");
             String path=actionMapping.getValue(result);
             System.out.println(path+"                path");
             request.getRequestDispatcher(path).forward(request,response);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

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

     public void init(ServletConfig config) throws ServletException {
         String fileName=config.getInitParameter("config");
         String file[]=null;
         if(fileName==null){
             file=new String[]{"Framework.xml"};
         }else {
             fileName.split(",");
         }
         try {
             manager=new ActionMappingManager(file);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }

配置web.xml文件

 <!DOCTYPE web-app PUBLIC
  "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
  "http://java.sun.com/dtd/web-app_2_3.dtd" >

 <web-app>
   <display-name>Archetype Created Web Application</display-name>
     <servlet>
         <servlet-name>LoginServlet</servlet-name>
         <servlet-class>cn.curry.servlet.LoginServlet</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>LoginServlet</servlet-name>
         <url-pattern>*.action</url-pattern>
     </servlet-mapping>
 </web-app>

jsp页面

login.jsp

 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 <html>
 <head>
     <title>登录</title>
 </head>
 <body>
 <form action="login.action" method="post">
     用户名：<input name="name"><br>
     密码：<input name="pwd"/><br/>
     <input type="submit" value="登陆"/>
 </form>
 </body>
 </html>

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2018/3/4
  Time: 19:43
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登录</title>
</head>
<body>
<h1>success！！！</h1>
</body>
</html>

执行结果;