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