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

 <%@ 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;

巴特西

自定义MVC实现登录案例

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