工程目录
一、说明
- 此实验只判断用户表中是否存在用户输入的账户，并没有进行注册写入数据库操作
- 焦点改变时触发函数
二、代码
Check.java
package witersen.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/Check")
public class Check extends HttpServlet {
private static final String DBDRIVER = "com.mysql.cj.jdbc.Driver";
private static final String DBURL = "jdbc:mysql://localhost:3306/demo1001?useSSL=false&serverTimezone=UTC";
private static final String DBUSER = "root";
private static final String DBPASSWORD = "";
public Check() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html");
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
PrintWriter out = response.getWriter();
String username = request.getParameter("username");
try {
Class.forName(this.DBDRIVER);
conn = DriverManager.getConnection(this.DBURL, this.DBUSER, this.DBPASSWORD);
String sql = "select count(id) from user where username=?";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, username);
rs = pstmt.executeQuery();
if (rs.next()) {
if (rs.getInt(1) > 0) {
out.print("true");
} else {
out.print("false");
}
}
pstmt.close();
out.close();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<script type="text/javascript">
var xmlHttp;
var flag;
function createXMLHttp() {
if (window.XMLHttpRequest) {
xmlHttp = new XMLHttpRequest();
} else {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
}
function checkUsername(username) {
createXMLHttp();
xmlHttp.open("POST", "Check?username="
+ username);
xmlHttp.onreadystatechange = checkUsernameCallback;
xmlHttp.send(null);
document.getElementById("msg").innerHTML = "正在验证.................";
}
function checkUsernameCallback() {
if (xmlHttp.readyState == 4) {
if (xmlHttp.status == 200) {
var text = xmlHttp.responseText;
if (text == "true") {
flag = false;
document.getElementById("msg").innerHTML = "<span style=\"color: #be3b3b\">用户名已被使用</span>";
document.getElementById("reg").setAttribute("disabled","true"); //设置不可点击
} else {
flag = true;
document.getElementById("msg").innerHTML = "<span style=\"color: #43cf78\">验证通过</span>";
document.getElementById("reg").removeAttribute("disabled"); //移除不可点击
}
}
}
}
</script>
<body>
<form method="post" action="">
用户名：<input type="text" name="username"
onblur="checkUsername(this.value)"><span id="msg"></span><br>
密码：<input type="password" name="password"> <br><input id="reg"
type="submit" value="注册"> <input type="reset" value="重置">
</form>
</body>
</html>
生成数据库的sql语句
CREATE DATABASE IF NOT EXISTS `demo1001` /*!40100 DEFAULT CHARACTER SET utf8 */ /*!80016 DEFAULT ENCRYPTION='N' */;
USE `demo1001`;
-- MySQL dump 10.13 Distrib 8.0.21, for Win64 (x86_64)
--
-- Host: localhost Database: demo1001
-- ------------------------------------------------------
-- Server version 8.0.21
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!50503 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
--
-- Table structure for table `user`
--
DROP TABLE IF EXISTS `user`;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!50503 SET character_set_client = utf8mb4 */;
CREATE TABLE `user` (
`username` varchar(45) NOT NULL,
`password` varchar(45) NOT NULL,
PRIMARY KEY (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;
--
-- Dumping data for table `user`
--
LOCK TABLES `user` WRITE;
/*!40000 ALTER TABLE `user` DISABLE KEYS */;
INSERT INTO `user` VALUES ('admin','admin'),('admin1','admin2'),('admin12','admin'),('witersen','witersen');
/*!40000 ALTER TABLE `user` ENABLE KEYS */;
UNLOCK TABLES;
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;
/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
-- Dump completed on 2020-12-09 10:58:49
原创文章，作者：witersen，如若转载，请注明出处：https://www.witersen.com
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