Eclipse新建web项目，实现登录验证功能
安装好MySQl数据库
新建JavaWeb项目
项目名称为test3
在Web-Content目录下新建login.jsp文件
在浏览器中，需要提交的东西，使用表单form标签来进行提交，form中的action的值是表单数据提交到的jsp或Servlet的地址
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Login Pagetitle>
head>
<body>
<form action="LoginServlet"> //此处的LoginServlet为相对位置
username:<input type ="text" name="username"/><br>
password:<input type = "password" name="password"/><br>
<input type ="submit" name ="submit"/>
form>
body>
html>新建名为MySQL的类来进行数据库操作
package com.lx.uestc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class MySQL {
private Connection connection = null;
public MySQL()
{
/*加载JdBC驱动
*
*/
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("load Driver successfully");
} catch (Exception e) {
System.out.println("load Driver error");
e.printStackTrace();
}
/*连接数据库
*
*/
try {
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","liangxi333");
//jdbc:mysql://localhost:端口号/数据库名称","用户名","密码"
System.out.println("connect sql successfully");
} catch (Exception e) {
System.out.println("connect sql erro");
e.printStackTrace();
}
/*检查用户账号密码正否
*
*/
}
/*连接数据库后要记得关闭
*
*/
private void CloseSqlConnect(Connection connection ){
if (connection != null)
try{
connection.close();
}catch (Exception e) {
e.printStackTrace();
}
}
private ResultSet execSQL(String sql,Object... args) throws SQLException{
//建立PreparedStatement对象
PreparedStatement pStmt = connection.prepareStatement(sql);
//为pStmt对象设置SQL参数值
for(int i = 0; i < args.length; i++){
pStmt.setObject(i+1, args[i]);
}
//执行SQL语句
pStmt.execute();
//返回结果集,如果执行的SQL语句不返回结果集，则返回null
return pStmt.getResultSet();
}
public String checkUser(String username,String password){
boolean has_username = false;
boolean password_correct = false;
ResultSet rs = null;
try {
rs = execSQL("select * from user");
} catch (SQLException e) {
System.err.println("查询数据库出错");
e.printStackTrace();
return null;
}
try {
while(rs.next()){
String temp_username = rs.getString("name").trim();
String temp_password = rs.getString("password").trim();
if(username.equals(temp_username)){
has_username = true;
if(password.equals(temp_password)){
password_correct = true;
return "hasUserNameAndPasswordCorrect";
}
return "hasUserNameButPasswordInCorrect";
}
}
} catch (SQLException e) {
System.err.println("操作ResultSet出错");
e.printStackTrace();
}
return "hasNoUserName";
}
}
新建LoginServlet来响应浏览器请求
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.OutputStream;
import java.io.PrintWriter;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public LoginServlet() {
super();
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
String username = request.getParameter("username");
String password = request.getParameter("password");
PrintWriter output = response.getWriter();
output.println(" hello ");
MySQL mss = new MySQL(); //实例化数据库对象
String result = mss.checkUser(username,password);
if (result.equals("hasUserNameAndPasswordCorrect")) {
output.println("user and password correct");
System.out.println("用户名和密码均正确");
} else if (result.equals("hasUserNameButPasswordInCorrect")) {
output.println("user correct but password wrong