自己写框架-MVC(一)

2016 年 2 月 18 日 jslfl 架构

通过简单的例子，介绍MVC框架基本原理

技术要点:
servlet

准备环境:
eclipse,jdk7,tomcat7

业务场景:
实现用户注册,登录功能

代码结构:

1、新建工程mvc_servlet_1
超级简单的jsp+servlet应用，后面在这基础上改造完善成mvc框架。

2、登陆功能
业务流程：访问登录页面login.jsp，提交登录表单、LoginServlet后台验证用户、跳转到userInfo.jsp页面，显示登录信息。

2.1、创建login.jsp登录表单页面、userInfo.jsp用户信息页面
WebContent/web/login.jsp代码清单:

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<%@ page language="java" contentType="text/html; 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>Login...</title>
</head>
<body>
<span>${info }</span>
<form action="<%=request.getContextPath() %>/login.do" method="post">
<h3>请登录</h3>
<p>用户:<input type="text" name="username" /></p>
<p>密码:<input type="text" name="password" /></p>
<p><input type="submit" value="提交"/></p>
</form>
</body>
</html>

WebContent/web/userInfo.jsp代码清单:

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<%@ 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>欢迎你...</title>
</head>
<body>
<span>${info }</span>
</body>
</html>

2.2、创建LoginForm.java，接收封装表单参数

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package cn.jslfl.mvc.demo.form;

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

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;
}
}

2.3、创建LoginServlet.java，后台业务处理

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package cn.jslfl.mvc.demo.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.demo.form.LoginForm;

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

public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("GBK");

LoginForm formBean = new LoginForm();
formBean.setUserName(req.getParameter("username"));
formBean.setPassWord(req.getParameter("password"));

//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);
req.getRequestDispatcher("/web/userInfo.jsp").forward(req, resp);
}

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

2.4、web.xml中添加配置LoginServlet

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<servlet>
<servlet-name>login</servlet-name>
<servlet-class>cn.jslfl.mvc.demo.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login.do</url-pattern>
</servlet-mapping>

2.5、发布到tomcat进行测试
访问登录页面，输入错误的用户名密码提交

输入正确的用户名密码aa/bb提交

3、注册功能
业务流程：访问注册页面reg.jsp，提交表单、RegServlet后台业务处理、跳转到登录页面login.jsp，显示注册信息。
3.1、创建WebContent/web/reg.jsp注册表单页面

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<%@ page language="java" contentType="text/html; 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>Reg...</title>
</head>
<body>
<span>${info }</span>
<form action="<%=request.getContextPath() %>/reg.do" method="post">
<h3>请注册</h3>
<p>用户:<input type="text" name="username" /></p>
<p>密码:<input type="text" name="password" /></p>
<p>密码2:<input type="text" name="password2" /></p>
<p><input type="submit" value="提交"/></p>
</form>
</body>
</html>

3.2、创建RegForm.java，接收封装表单参数

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package cn.jslfl.mvc.demo.form;

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

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;
}
}

3.3、创建RegServlet.java，后台业务处理

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package cn.jslfl.mvc.demo.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.jslfl.mvc.demo.form.RegForm;

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

public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setCharacterEncoding("GBK");

String userName = req.getParameter("username");
String pwd = req.getParameter("password");
String pwd2 = req.getParameter("password2");

RegForm regBean = new RegForm();
regBean.setUserName(userName);
regBean.setPassWord(pwd);
regBean.setPassWord2(pwd2);

//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(!pwd.equals(pwd2)){
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: " + userName + ", " + "password: " + pwd + ", " + "password2: " + pwd2 +"</h1>";

req.setAttribute("info", info);
req.getRequestDispatcher("/web/login.jsp").forward(req, resp);
}

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

3.4、web.xml中添加配置RegServlet

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<servlet>
<servlet-name>reg</servlet-name>
<servlet-class>cn.jslfl.mvc.demo.servlet.RegServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>reg</servlet-name>
<url-pattern>/reg.do</url-pattern>
</servlet-mapping>

3.5、发布到tomcat进行测试
访问注册页面，两次密码输入不一致提交

两次密码输入相同提交

本节已完成jsp+servlet技术来实现登录注册的简单业务，下一节中对其进行完善改造。
完整的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_servlet_1</display-name>

<servlet>
<servlet-name>login</servlet-name>
<servlet-class>cn.jslfl.mvc.demo.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login.do</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>reg</servlet-name>
<servlet-class>cn.jslfl.mvc.demo.servlet.RegServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>reg</servlet-name>
<url-pattern>/reg.do</url-pattern>
</servlet-mapping>
</web-app>

mvc

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