Servlet登錄實例
在這裏，我們將創建一個使用servlet創建登錄表單的簡單示例，在這個示例中使用MySQL作爲數據庫。
實現的主要功能：
- 顯示登錄表單輸入框(用戶名，密碼)。
- 在表單中填寫用戶名，密碼並提交。
- 在Servlet中接收提交的用戶名和密碼，與數據庫表中的數據進行比較。
- 匹配用戶名和密碼，則提示成功；不匹配則提示失敗。
需要創建一個用戶表：servlet_user。 此外，它必須包含一些數據。表結構及數據記錄如下：
DROP TABLE IF EXISTS `servlet_user`;
CREATE TABLE `servlet_user` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(64) NOT NULL DEFAULT '',
`passwd` varchar(32) NOT NULL DEFAULT '',
`email` varchar(32) DEFAULT NULL,
`city` varchar(24) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of servlet_user
-- ----------------------------
INSERT INTO `servlet_user` VALUES ('1', 'maxsu', '123456', '[email protected]', '廣州');
INSERT INTO `servlet_user` VALUES ('2', 'minsu', '233123', '[email protected]', '海口');
INSERT INTO `servlet_user` VALUES ('3', 'avguser', 'fdsa123', '[email protected]', '廣州');
INSERT INTO `servlet_user` VALUES ('4', 'sumuser', 'fdsj124', '[email protected]', '北京');打開Eclipse，創建一個動態Web項目：ServletLogin，其完整的目錄結構如下所示 -
以下是這個項目中的幾個主要的代碼文件。
- index.html
- LoginServlet.java
- LoginDao.java
- WelcomeServlet.java
- web.xml
以下是各個文件中的實現代碼。
文件：index.html -
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>用戶登錄示例</title>
</head>
<body>
<div style="margin: auto; text-align: center;">
<form action="login" method="post">
用戶名：<input type="text" name="username" /> 密 碼：<input
type="password" name="passwd" /> <input type="submit"
value="登 錄" />
</form>
</div>
</body>
</html>文件：LoginServlet.java -
package com.yiibai.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
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 com.yiibai.dao.LoginDao;
public class LoginServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
String username = request.getParameter("username");
String passwd = request.getParameter("passwd");
if (LoginDao.doLogin(username, passwd)) {
HttpSession session = request.getSession();
session.setAttribute("username", username);
RequestDispatcher rd = request.getRequestDispatcher("welcome");
rd.forward(request, response);
} else {
out.print("用戶名或密碼錯誤~！");
RequestDispatcher rd = request.getRequestDispatcher("index.html");
rd.include(request, response);
}
out.close();
}
}文件：LoginDao.java -
package com.yiibai.dao;
import java.sql.*;
public class LoginDao {
public static boolean doLogin(String username, String passwd) {
System.out.println("UserName : "+username+", Passwd："+passwd);
boolean status = false;
Connection con = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost/testdb?useSSL=false&characterEncoding=utf8", "root", "123456");
// 用戶名及密碼是否正確？
PreparedStatement ps = con.prepareStatement("SELECT * FROM servlet_user WHERE name=? AND passwd=?");
ps.setString(1, username);
ps.setString(2, passwd);
ResultSet rs = ps.executeQuery();
status = rs.next();
} catch (Exception e) {
System.out.println(e);
}
return status;
}
}文件：WelcomeServlet.java -
package com.yiibai.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;
public class WelcomeServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
HttpSession session = request.getSession();
String username = (String) session.getAttribute("username");
out.print("登錄成功~！<br/>");
out.print("歡迎您，" + username);
out.close();
}
}文件：web.xml -
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
id="WebApp_ID" version="3.1">
<display-name>ServletLogin</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.yiibai.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>WelcomeServ</servlet-name>
<servlet-class>com.yiibai.servlet.WelcomeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>WelcomeServ</servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
</web-app>在編寫上面代碼後，部署此Web應用程序(在項目名稱上點擊右鍵->」Run On Server…」)，打開瀏覽器訪問URL： http://localhost:8080/ServletLogin/ ，如果沒有錯誤，應該會看到以下結果 -
登錄成功後的界面，如下所示 -
