JSP MVC

Java的MVC玩起来比.Net的有意思，因为每一步你都知道它是如何运作的，都由自己去实现。而在.Net的MVC中，你却不知道一个Controller是如何对应到View中的，因为MS给了你IDE上的操作方便，具体内部是如何做的映射，很难找到或不知道。

Java MVC的原理可有这样理解（网上说是这种）：JSP -> Servlet -> JSP

（个人认为最合适的是这样解释比较好）：Servlet -> JSP

即不需要让用户直接访问JSP。因为这是Resful风格哈。

上代码例子。

建一个Bean: User

package com.my.beans;

import java.lang.*;

public class User {

    private String name;

    private String password;

    private int age;

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

    public int getAge() {

        return age;

    }

    public void setAge(int age) {

        this.age = age;

    }

    public User() {}

}

建一个JSP：mvctest.jsp

<%@ page contentType="text/html;charset=utf-8" pageEncoding="utf-8"%>

<html>

    <header>

        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">

    </header>

    <body>

        <form action="${pageContext.request.contextPath}/requestattr" method="POST">

            User name: <input type="textbox" id="txtUserName" name="txtUserName" value="${param.txtUserName}" />

            <input type="submit" value="Submit" /><br/>

            <hr />

            User name textbox value: ${param.txtUserName}<br/>

            Bean user name value: ${userBean.name}<br/>

            Bean password value: ${userBean.password}<br/>

            Bean age value: ${userBean.age}<br/>

        </form>

    </body>

</html>

建一个Servlet: RequestAttr

package com.my;

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import com.my.beans.User;

public class RequestAttr extends HttpServlet {

    public RequestAttr() {}

    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {

        req.getRequestDispatcher("/pages/mvctest.jsp").forward(req, resp);

    }

    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {

        PrintWriter out = resp.getWriter();

        String strUserName = req.getParameter("txtUserName");

        User user = new User();

        user.setName(strUserName);

        user.setPassword("123");

        user.setAge(18);

        req.setAttribute("userBean", user);

        req.getRequestDispatcher("/pages/mvctest.jsp").forward(req, resp);

    }

}

web.xml修改：

    <servlet>

      <servlet-name>requestattr</servlet-name>

      <servlet-class>com.my.RequestAttr</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>requestattr</servlet-name>

        <url-pattern>/requestattr</url-pattern>

    </servlet-mapping>

结果：

访问地址：http://localhost:8080/mytest/requestattr

一个MVC模型如来。性奋....

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