自己写框架-MVC(四)

2016 年 2 月 18 日 jslfl 架构

技术要点:
xml解析
监听器
java多态特性
反射

改造计划：
模仿struts实现通过xml文件来配置请求对应的action处理器、请求表单、跳转路径，整个过程由框架自动完成(创建分发action处理器、封装formbean、请求跳转)。

代码结构:

1、创建mvc配置文件mvc-config
resource/mvc-config.xml代码清单：

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<?xml version="1.0" encoding="UTF-8"?>
<mvc-config>
<action name="login" class="cn.jslfl.mvc.demo.action.LoginAction" form="cn.jslfl.mvc.demo.form.LoginForm">
<result name="success">/web/userInfo.jsp</result>
<result name="error">/web/login.jsp</result>
</action>

<action name="reg" class="cn.jslfl.mvc.demo.action.RegAction" form="cn.jslfl.mvc.demo.form.RegForm">
<result name="success">/web/login.jsp</result>
<result name="error">/web/reg.jsp</result>
</action>
</mvc-config>

2、mvc-config.xml解析处理
2.1、创建MvcConfig.java，定义配置文件结构名称常量
MvcConfig.java代码清单：

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package cn.jslfl.mvc.core.config;

/**
* mvc配置文件结构名称定义
* @author jslfl
*
*/
public class MvcConfig {
public static final String ACTION_ATTR = "attr";
public static final String ACTION_RESULT = "result";
public static final String ACTION_NAME = "name";
public static final String ACTION_CLASS = "class";
public static final String ACTION_FORM = "form";
public static final String RESULT_NAME = "name";
public static final String MVC_CONFIG = "mvc_config";
}

2.2、创建ParseMvcConfig.java来做mvc-config.xml解析处理
ParseMvcConfig代码清单：

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package cn.jslfl.mvc.core.config;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

/**
* mvc配置文件解析操作
* @author jslfl
*
*/
public class ParseMvcConfig {
/**
* 解析完成后返回数据结构示例
* {
* login:
*    {
*    attr:{name:'login', class:'cn.action.Login', form:'cn.form.LoginForm'},
*    result:{success:'login.jsp', error:'error.jsp'}
*    },
* reg:
*    {
*    attr:{name:'reg', class:'cn.action.Reg', form:'cn.form.RegForm'},
*    result:{success:'login.jsp', error:'error.jsp'}
*    }
* }
*/
@SuppressWarnings("unchecked")
public static Map<String, Map<String,Map<String,String>>> parse(String xmlPath){
Map<String, Map<String,Map<String,String>>> actionMap = new HashMap<String, Map<String,Map<String,String>>>();

SAXReader reader = new SAXReader();
try {
Document doc = reader.read(new File(xmlPath));
Element root = doc.getRootElement();
List<Element> actionElementList = root.elements();
for(Element actionElement : actionElementList){
Map<String, Map<String,String>> action = new HashMap<String, Map<String,String>>();

//action节点属性
String actionName = actionElement.attribute(MvcConfig.ACTION_NAME).getStringValue();
Map<String,String> attr = new HashMap<String,String>();
attr.put(MvcConfig.ACTION_NAME, actionName);
attr.put(MvcConfig.ACTION_CLASS, actionElement.attribute(MvcConfig.ACTION_CLASS).getStringValue());
attr.put(MvcConfig.ACTION_FORM, actionElement.attribute(MvcConfig.ACTION_FORM).getStringValue());

//action节点下result子节点
List<Element> resultElementList = actionElement.elements();
Map<String,String> result = new HashMap<String,String>();
for(Element resultElement : resultElementList){
result.put(resultElement.attributeValue(MvcConfig.RESULT_NAME), resultElement.getText());
}

action.put(MvcConfig.ACTION_ATTR, attr);
action.put(MvcConfig.ACTION_RESULT, result);
actionMap.put(actionName, action);
}
} catch (DocumentException e) {
e.printStackTrace();
}
return actionMap;
}
}

本例中使用dom4j来解析xml，所以需要引入dom4j的jar包,并且解析结果使用Map来存储,最好方式是定义相应pojo类来存储。

3、创建监听器ActionServletListener.java，ActionServlet初始化时调用解析mvc-config.xml，结果存入servlet上下文
ActionServletListener.java代码清单：

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package cn.jslfl.mvc.core.listener;

import java.util.Map;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import cn.jslfl.mvc.core.config.MvcConfig;
import cn.jslfl.mvc.core.config.ParseMvcConfig;
/**
* ActionServlet初始化时解析mvc-config.xml
* @author jslfl
*/
public class ActionServletListener implements ServletContextListener {
@Override
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("mvc-framework: 系统退出!");
}

@Override
public void contextInitialized(ServletContextEvent arg0) {
String xmlPath = arg0.getServletContext().getInitParameter("mvc-config");
System.out.println("mvc-framework: 取得参数mvc配置文件路径: " + xmlPath);//print================

String mvcXmlPath = this.getClass().getClassLoader().getResource(xmlPath).getPath();//类路径下的配置文件
System.out.println("mvc-framework: 取得参数mvc配置文件路径: " + mvcXmlPath);//print================

//解析mvc配置文件
Map<String, Map<String,Map<String,String>>> actionMap = ParseMvcConfig.parse(mvcXmlPath);
System.out.println("mvc-framework: mvc配置加载成功!");//print================
System.out.println("mvc-framework: mvc配置信息:");//print================
System.out.println(actionMap);//print================

arg0.getServletContext().setAttribute(MvcConfig.MVC_CONFIG, actionMap);
}
}

4、改造formbean
4.1、定义formbean的基类
ActionFormBean.java代码清单：

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package cn.jslfl.mvc.core.form;
/**
* mvc 中from表单的父类
* @author jslfl
*/
public class ActionFormBean {

}

4.2、FormBeanUtil.java改名为ActionFormBeanUtil.java，并返回ActionFormBean对象
FormBeanUtil.java代码清单：

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package cn.jslfl.mvc.core.form;

import java.lang.reflect.Field;
import javax.servlet.http.HttpServletRequest;

/**
* 自动解析封装FormBean对象
* @author jslfl
*
*/
public class ActionFormBeanUtil {
@SuppressWarnings("rawtypes")
public static ActionFormBean packFormBean(HttpServletRequest req, String formBeanName){
ActionFormBean form = null;
try {
Class c = Class.forName(formBeanName);
form = (ActionFormBean)c.newInstance();

Field[] fieldArr = c.getDeclaredFields();
for(Field f : fieldArr){
f.setAccessible(true);
f.set(form, req.getParameter(f.getName()));
f.setAccessible(false);
}
} catch (Exception e) {
e.printStackTrace();
}
return form;
}
}

4.3、重构LoginForm、RegForm，让它们继承ActionFormBean类
LoginForm.java代码清单：

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package cn.jslfl.mvc.demo.form;

import cn.jslfl.mvc.core.form.ActionFormBean;

public class LoginForm extends ActionFormBean{
private String userName;
private String passWord;

public LoginForm(){
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
}

RegForm.java代码清单：

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package cn.jslfl.mvc.demo.form;

import cn.jslfl.mvc.core.form.ActionFormBean;

public class RegForm extends ActionFormBean {
private String userName;
private String passWord;
private String passWord2;

public RegForm(){
}
public String getPassWord2() {
return passWord2;
}
public void setPassWord2(String passWord2) {
this.passWord2 = passWord2;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
}

5、改造action
5.1、创建action接口MvcAction.java
MvcAction.java代码清单：

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package cn.jslfl.mvc.core.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.core.form.ActionFormBean;

/**
* Action接口
* @author jslfl
*/
public interface MvcAction {
public String doService(ActionFormBean formBean, HttpServletRequest req, HttpServletResponse resp);
}

5.2、重构LoginAction、RegAction，实现MvcAction接口，doService调用参数改为ActionFormBean
LoginAction代码清单：

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package cn.jslfl.mvc.demo.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.core.action.MvcAction;
import cn.jslfl.mvc.core.form.ActionFormBean;
import cn.jslfl.mvc.demo.form.LoginForm;

public class LoginAction implements MvcAction {
public LoginAction(){
}

public String doService(ActionFormBean actionFormBean, HttpServletRequest req, HttpServletResponse resp){
LoginForm formBean = (LoginForm)actionFormBean;
//业务处理开始...
boolean flag = false;
if("aa".equals(formBean.getUserName()) && "bb".equals(formBean.getPassWord())){
flag = true;
}
//业务处理结束...

String info = "<h1>登录" + (flag ? "成功" : "失败") + "!userName: " + formBean.getUserName()+ ", " + "password: " + formBean.getPassWord() + "</h1>";
req.setAttribute("info", info);
if(flag)
return "success";
return "error";
}
}

RegAction代码清单：

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package cn.jslfl.mvc.demo.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.core.action.MvcAction;
import cn.jslfl.mvc.core.form.ActionFormBean;
import cn.jslfl.mvc.demo.form.RegForm;

public class RegAction implements MvcAction {
public RegAction(){
}

public String doService(ActionFormBean actionFormBean, HttpServletRequest req, HttpServletResponse resp){
RegForm regBean = (RegForm)actionFormBean;
//业务处理开始...
String msg = "";
if(regBean.getUserName() == null || "".equals(regBean.getUserName().trim())
||regBean.getPassWord() == null || "".equals(regBean.getPassWord().trim())
|| regBean.getPassWord2() == null || "".equals(regBean.getPassWord2().trim())){
msg = "数据不完整";
}else if(!regBean.getPassWord().equals(regBean.getPassWord2())){
msg = "两次密码不匹配";
}else{
msg = "成功";
}

//业务处理结束...

String info = "<h1>注册" + msg + "!userName: " + regBean.getUserName() + ", " + "password: " + regBean.getPassWord() + ", " + "password2: " + regBean.getPassWord2() +"</h1>";
req.setAttribute("info", info);
if("成功".equals(msg))
return "success";
return "error";
}
}

6、改造ActionServlet
从ServletContext中取出mvc-config.xml的配置信息，通过actionName取得配置中请求映射action的信息，再创建FormBean、创建Action，调用action.doService，取得返回路径进行跳转

ActionServlet.java代码清单：

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package cn.jslfl.mvc.core.servlet;

import java.io.IOException;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.core.action.MvcAction;
import cn.jslfl.mvc.core.config.MvcConfig;
import cn.jslfl.mvc.core.form.ActionFormBean;
import cn.jslfl.mvc.core.form.ActionFormBeanUtil;

public class ActionServlet extends HttpServlet{
private static final long serialVersionUID = 1L;

@SuppressWarnings({ "unchecked", "rawtypes" })
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("GBK");

//取得请求名称,对应action名称
String reqPath = req.getServletPath();
String actionName = reqPath.substring(1, reqPath.lastIndexOf(".do"));//截取 "/login.do" -> "login"
System.out.println("mvc-framework: 请求路径: " + reqPath + " actionName: " + actionName );//print================

//得到action配置信息
Map<String, Map<String,Map<String,String>>> actionMap =
(Map<String, Map<String,Map<String,String>>>)req.getServletContext().getAttribute(MvcConfig.MVC_CONFIG);
Map<String,Map<String,String>> actionCfg = actionMap.get(actionName);
System.out.println("mvc-framework: action信息: " + actionCfg);//print================

//自动封装FormBean
ActionFormBean formBean = ActionFormBeanUtil.packFormBean(req, actionCfg.get(MvcConfig.ACTION_ATTR).get(MvcConfig.ACTION_FORM));

//调用业务action
String result = "";
try {
Class actionClass = Class.forName(actionCfg.get(MvcConfig.ACTION_ATTR).get(MvcConfig.ACTION_CLASS));
MvcAction action = (MvcAction)actionClass.newInstance();
result = action.doService(formBean, req, resp);
} catch (Exception e) {
e.printStackTrace();
}
req.getRequestDispatcher(actionCfg.get(MvcConfig.ACTION_RESULT).get(result)).forward(req, resp);
}

public void doGet(HttpServletRequest req, HttpServletResponse resp){
try {
doPost(req, resp);
} catch (Exception e) {
e.printStackTrace();
}
}
}

7、修改web.xml配置
web.xml代码清单：

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID" version="3.0">
<display-name>mvc_framework</display-name>


<context-param>
<param-name>mvc-config</param-name>
<param-value>/mvc-config.xml</param-value>
</context-param>
<listener >
<listener-class>cn.jslfl.mvc.core.listener.ActionServletListener</listener-class>
</listener>
<servlet>
<servlet-name>mvc</servlet-name>
<servlet-class>cn.jslfl.mvc.core.servlet.ActionServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>mvc</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>

</web-app>

8、发布测试