Jsp+Servlet+JDBC 登录
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1.index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--> </head> <body> <!-- Form 用来提取用户填入并提交的信息--> <form method = "post" name = "frmLogin" action = "LoginServlet"> <h1 align = "center"> 用户登录</h1> <br> <div align = "center"> 用户名： <input type = "text" name = "txtUserName" value = "Your name" size = "20" maxlength = "20" onfocus = "if(this.value=='Your name')this.value='';"> <br> 密码： <input type = "password" name = "txtPassword" value = "Your password" size = "20" maxlength = "20" onfocus = "if(this.value=='Your password')this.value='';"> <br> <input type = "submit" name = "Submit" value= "提交" onClick = "validateLogin();" > <input type = "reset" name = "Reset" value = "重置"> <br> </div> </form> <!-- javaScript 函数 validateLogin(),用来验证用户名和密码是否为空 --> <script language = "javaScript"> function validateLogin( ) { var sUserName = document. frmLogin. txtUserName. value ; var sPassword = document. frmLogin. txtPassword. value ; if( sUserName== "" ) { alert( "请输入用户名！" ) ; return false; } if( sPassword== "" ) { alert( "请输入密码！" ) ; return false; } } </script> </body></html>
2.LoginServlet.java
package com.rt.login;import java.io.IOException;import java.io.PrintWriter;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServlet extends HttpServlet {/** * Constructor of the object. */public LoginServlet() {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 {response.setContentType("text/html");PrintWriter out = response.getWriter();out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");out.println("<HTML>");out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");out.println(" <BODY>");out.print(" This is ");out.print(this.getClass());out.println(", using the GET method");out.println(" </BODY>");out.println("</HTML>");out.flush();out.close();}/** * 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 {response.setContentType( "text/html" ); String result = ""; // 获取用户名String sUserName = request.getParameter( "txtUserName" ); if ( sUserName == "" || sUserName == null || sUserName.length() > 20 ) { try { result = "请输入用户名（不超过20 字符）！" ; request.setAttribute( "ErrorUserName" , result ) ; response.sendRedirect( "login.html" ) ; } catch ( Exception e ) { e.printStackTrace(); } } // 获取密码String sPasswd = request.getParameter ( "txtPassword" ) ; if ( sPasswd == "" || sPasswd == null || sPasswd. length ( ) > 20 ) { try { result = "请输入密码（不超过20字 符）！" ; request.setAttribute ( "ErrorPassword" , result ) ; response.sendRedirect ( "login.html" ) ; } catch ( Exception e ) { e.printStackTrace(); } } // 登记JDBC驱动程序try { Class.forName ( "com.mysql.jdbc.Driver" ).newInstance( ) ; } catch ( InstantiationException e ) { e.printStackTrace(); System.out.println( "InstantiationException" ) ; } catch ( IllegalAccessException e ) { e.printStackTrace(); System.out.println( "IllegalAccessException" ) ; } catch ( ClassNotFoundException e ) { e.printStackTrace(); System.out.println( "ClassNotFoundException" ) ; } // 连接参数与Access不同String url = "jdbc:mysql://localhost/myoa_dec31" ; // 建立连接java.sql.Connection connection = null ; Statement stmt = null ; ResultSet rs = null ; try { connection = DriverManager.getConnection( url , "root" , "890307" ) ; stmt = connection.createStatement () ; // SQL语句 String sql = "select * from loginuser where username='" + sUserName + "' and userpwd = '" + sPasswd + "'" ; rs = stmt.executeQuery ( sql ) ; // 返回查询结果 } catch ( SQLException e ) { e.printStackTrace () ; } try { if ( rs. next () ) // 如果记录集非空，表明有匹配的用户名和密码，登陆成功 { // 登录成功后将sUserName设置为session变量的UserName // 这样在后面就可以通过 session.getAttribute("UserName") 来获取用户名， // 同时这样还可以作为用户登录与否的判断依据 request.getSession().setAttribute( "UserName" , sUserName ) ; response.sendRedirect( "success.jsp" ) ; } else { // 否则登录失败 //response.sendRedirect ( "index.jsp" ); response.sendRedirect( "login_failure.jsp" ) ; } } catch ( SQLException e ) { e.printStackTrace (); } try { if ( null!=rs ) { rs.close() ; } if ( null!=stmt ) { stmt.close() ; } if ( null!=connection ) { connection.close() ; } } catch ( SQLException e ) { e. printStackTrace() ; } }/** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */public void init() throws ServletException {// Put your code here}}
3.web.xml
<?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>LoginServlet</display-name> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.rt.login.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>
