架构实例之Demo_JSP_JavaBean

架构实例之Demo_JSP_JavaBean_Servlet

1、开发工具和开发环境

开发工具： MyEclipse10，JDK1.6.0_13(32位)，Tomcat7.0（32位），mysql5.7.13

开发环境：WIN10

2、Demo_JSP_JavaBean_Servlet实现功能

用户登录、用户注册、退出登录。

3、Demo_JSP_Java_Bean_Servlet使用技术

本实例使用了JSP、JavaBean、Servlet和JDBC来实现用户登录、用户注册和退出登录功能。系统架构图如图一所示：

图一：Demo_JSP_Java_Bean_Servlet系统架构图

下面请看图二（系统中JSP、JavaBean和Servlet之间的逻辑关系图）：

图二：系统中JSP、JavaBean和Servlet之间的逻辑关系图

4、具体实现

本篇博客实例代码是基于本人上一篇博客代码修改而来，其中修改的部分是增加了一个Servlet,并删除了JSP文件中处理逻辑层的文件，接下来主要讲解一下修改的部分——Servlet:

首先在项目Demo_JSP_Java_Bean_Servlet中新建一个Servlet类：类名命名为UserServlet，包名命名为liu_servlet，该Servlet类主要实现用户登录、注册和退出的逻辑处理，并且调用JavaBean来操作数据库。UserServlet类的具体代码如下：

package liu_servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import liu.UserBean;

public class UserServlet extends HttpServlet {

    /**

     *

     */

    private static final long serialVersionUID = 1L;

    /**

     * Constructor of the object.

     */

    public UserServlet() {

        super();

    }

    /**

     * Destruction of the servlet. <br>

     */

    public void destroy() {

        super.destroy(); // Just puts "destroy" string in log

        // Put your code here

    }

    /**

     * The doGet method of the servlet. <br>

     *

     * This method is called when a form has its tag value method equals to get.

     *

     * @param request the request send by the client to the server

     * @param response the response send by the server to the client

     * @throws ServletException if an error occurred

     * @throws IOException if an error occurred

     */

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        String method = (String)request.getParameter("method");

        if(method==null) {

            PrintWriter out = response.getWriter();

            out.println("invalid request!");

        } else if(method.equals("login")) {

            Login(request, response);

        } else if(method.equals("logout")) {

            Logout(request, response);

        } else if(method.equals("register")) {

            Register(request, response);

        }

    }

    /**

     * The doPost method of the servlet. <br>

     *

     * This method is called when a form has its tag value method equals to post.

     *

     * @param request the request send by the client to the server

     * @param response the response send by the server to the client

     * @throws ServletException if an error occurred

     * @throws IOException if an error occurred

     */

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

         doGet(request,response);

    }

    /**

     * Initialization of the servlet. <br>

     *

     * @throws ServletException if an error occurs

     */

    protected void Login(HttpServletRequest request,

            HttpServletResponse response) throws ServletException, IOException {

        // get parameters

        String username = request.getParameter("username");

        String password = request.getParameter("password");

        // check null

        if (username == null || password == null) {

            response.sendRedirect("login.jsp");

            return;

        }

        // validate

        UserBean userBean = new UserBean();

        boolean isValid = userBean.valid(username, password);

        if (isValid) {

            HttpSession session = request.getSession();

            session.setAttribute("username", username);

            response.sendRedirect("welcome.jsp");

            return;

        } else {

            response.sendRedirect("login.jsp");

            return;

        }

    }

    protected void Logout(HttpServletRequest request,

            HttpServletResponse response) throws ServletException, IOException {

        HttpSession session = request.getSession();

        session.removeAttribute("username");

        response.sendRedirect("login.jsp");

    }

    protected void Register(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        // get parameters

        String username = request.getParameter("username");

        String password1 = request.getParameter("password1");

        String password2 = request.getParameter("password2");

        String email = request.getParameter("email");

        // check null

        if (username == null || password1 == null || password2 == null || !password1.equals(password2)) {

            response.sendRedirect("register.jsp");

            return;

        }

        // validate

        UserBean userBean = new UserBean();

        boolean isExist = userBean.isExist(username);

        if(!isExist) {

            userBean.add(username, password1, email);

            response.sendRedirect("login.jsp");

            return;

        } else {

            response.sendRedirect("register.jsp");

            return;

        }

    }

    public void init() throws ServletException {

        // Put your code here

    }

}

接下来，查看Demo_JSP_Java_Bean_Servlet项目下web.xml文件，其中我的web.xml文件代码如下：

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="3.0"

    xmlns="http://java.sun.com/xml/ns/javaee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

  <display-name></display-name>

  <servlet>

    <description>This is the description of my J2EE component</description>

    <display-name>This is the display name of my J2EE component</display-name>

    <servlet-name>UserServlet</servlet-name>

    <servlet-class>liu_servlet.UserServlet</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>UserServlet</servlet-name>

    <url-pattern>/UserServlet</url-pattern>

  </servlet-mapping>

  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>

  </welcome-file-list>

</web-app>

注意：<url-pattern>/UserServlet</url-pattern>这一句我是打开后修改的，未修改之前的代码应该是：<url-pattern>/servlet/UserServlet</url-pattern>。如果不把/servlet去掉，到时进行逻辑处理跳转界面时，就会出现在URL中多出了.../servlet/welcome.jsp，从而报Tomcat中没有welcome.jsp编译文件的错误。

其他部分代码以及结果展示请查看本人上一篇博客哦：http://www.cnblogs.com/liuzhen1995/p/5700789.html

附：Demo_JSP_Java_Bean_Servlet项目源码文件百度云下载链接：http://pan.baidu.com/s/1geEOyht 密码：zhu4

巴特西

架构实例之Demo_JSP_JavaBean_Servlet

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