今天我学习了自定义一个简单的MVC框架，这个我们首先要知道什么是MVC框架！
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。
我们先看一下整体架构
我们用的是intellij idea这个工具。我们会创建一个maven项目，然后在pom文件导入我们需要的两个jar包，一个是dom4j的，一个是javaee的
下面是两个节点
<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>Y2166</artifactId> ???????<groupId>cn.happy</groupId> ???????<version>1.0-SNAPSHOT</version> ???</parent> ???<modelVersion>4.0.0</modelVersion> ???<artifactId>CustomMVC</artifactId> ???<packaging>war</packaging> ???<name>CustomMVC Maven Webapp</name> ???<url>http://maven.apache.org</url> ???<dependencies> ???????<dependency> ???????????<groupId>junit</groupId> ???????????<artifactId>junit</artifactId> ???????????<version>3.8.1</version> ???????????<scope>test</scope> ???????</dependency> ???????<dependency> ???????????<groupId>dom4j</groupId> ???????????<artifactId>dom4j</artifactId> ???????????<version>1.6.1</version> ???????</dependency> ???????<!--ServletAPI--> ???????<dependency> ???????????<groupId>javax</groupId> ???????????<artifactId>javaee-api</artifactId> ???????????<version>7.0</version> ???????????<scope>provided</scope> ???????</dependency> ???</dependencies> ???<build> ???????<resources> ???????????<resource> ???????????????<directory>src/main/java</directory> ???????????????<includes> ???????????????????<include>**/*.*</include> ???????????????</includes> ???????????</resource> ???????</resources> ???</build></project>
我们要定义自己的配置文件myframe.xml.我们要定义自己的dtd文件约束和配置信息
<?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>
然后建好包开始创建我们需要的类和接口。
首先我们定义自己的Action接口，在这个接口里我们简单定义了两个字符串常量，还有一个抽象的execute方法，我们最后看实现。
package cn.curry.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * @Auther: Xiao Yu * @Date: Created in 17:53 2018/3/3 */public interface Action { ???public static final String SUCCESS="success"; ???public static final String LOGIN="login"; ???public String execute(HttpServletRequest request, HttpServletResponse response) throws Exception;}然后我们定义一个ActionManager管理类，我们通过类名用反射机制获取对象。
package cn.curry.action;/** * @Auther: Xiao Yu * @Date: Created in 17:53 2018/3/3 */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; ???}}然后我们再定义一个ActionMapping类，这个类定义了几个属性，类似于实体类的作用。
package cn.curry.action;/** * @Auther: Xiao Yu * @Date: Created in 17:54 2018/3/3 */import java.util.HashMap;import java.util.Map;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); ???}}然后我们要做解析XML的类，我们的类ActionMappingManager ，我们通过读取用jdom4j读取xml，然后把数据添加到集合中。
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;/** * @Auther: Xiao Yu * @Date: Created in 17:54 2018/3/3 */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); ???????} ???}}定义自己的LoginAction封装业务逻辑
package cn.curry.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * @Auther: Xiao Yu * @Date: Created in 17:54 2018/3/3 */public class LoginAction implements Action{ ???public String execute(HttpServletRequest request, HttpServletResponse response) throws Exception { ???????String name = request.getParameter("name"); ???????if(name.equals("1")){ ???????????return "success"; ???????}else { ???????????return "login"; ???????} ???}}接下来我们要定义一个servlet来获取请求，LoginServlet.主要通过获取的请求来找到myframe.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 org.omg.PortableInterceptor.ACTIVE;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;/** * @Auther: Xiao Yu * @Date: Created in 17:54 2018/3/3 */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); ???} ???@Override ???public void init(ServletConfig config) throws ServletException { ???????String fileName=config.getInitParameter("config"); ???????String file[]=null; ???????if(fileName==null){ ???????????file=new String[]{"myframe.xml"}; ???????}else { ???????????fileName.split(","); ???????} ???????try { ???????????manager=new ActionMappingManager(file); ???????} catch (Exception e) { ???????????e.printStackTrace(); ???????} ???}}最后我们配置一下web.xml，然后就书写页面
<!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> ?<welcome-file-list> ???<welcome-file>login.jsp</welcome-file> ?</welcome-file-list></web-app>
书写页面，我们准备了两个页面，一个login.jsp。一个success.jsp。
首先看login.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> ?<head> ???<base href="<%=basePath%>"> ???<title>登陆页面</title> ???<meta http-equiv="pragma" content="no-cache"> ???<meta http-equiv="cache-control" content="no-cache"> ???<meta http-equiv="expires" content="0"> ???????<meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> ???<meta http-equiv="description" content="This is my page"> ???<!-- ???<link rel="stylesheet" type="text/css" href="styles.css"> ???--> ?</head> ?<body> ?<form action="login.action" method="POST"> ?????<input name="name"><br> ?????<input type="submit" value="登陆"/> ?</form> ?</body></html>
然后看success.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> ?<head> ???<base href="<%=basePath%>"> ???<title>SUCCESS</title> ???<meta http-equiv="pragma" content="no-cache"> ???<meta http-equiv="cache-control" content="no-cache"> ???<meta http-equiv="expires" content="0"> ????<meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> ???<meta http-equiv="description" content="This is my page"> ???<!-- ???<link rel="stylesheet" type="text/css" href="styles.css"> ???--> ?</head> ?<body> ?<h2>登录成功</h2> ?</body></html>
最后我们看一下运行效果
登陆成功跳到success.jsp页面
看一下登陆失败
登陆失败重新跳到登陆页面
ideat使用struts2之自定义MVC框架
原文地址：https://www.cnblogs.com/lcycn/p/8502607.html