ajax连接数据库验证用户名存在问题
CheckServlet
-----------------------------------------
package servlets;
import java.io.*;
import java.sql.*;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServlet;
public class CheckServlet extends HttpServlet{
public static final String DBDRIVER="com.mysql.jdbc.Driver";
public static final String DBURL="jdbc:mysql://localhost:8889/username";
public static final String DBUSER="root";
public static final String DBPASS="root";
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException{
this.doPost(request, response);
}
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException{
request.setCharacterEncoding("gbk");
response.setContentType("text/html");
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
PrintWriter out=response.getWriter();
String userid=request.getParameter("userid");//接受验证的用户名
out.println(userid);
try{
Class.forName(DBDRIVER);
conn=DriverManager.getConnection(DBURL,DBUSER,DBPASS);
String sql=" select * from name where username=?";
pstmt=conn.prepareStatement(sql);
pstmt.setString(1,userid);
rs=pstmt.executeQuery();
if(rs.next()){
if(rs.getString("username")==userid){
out.println("true");
}else{
out.println("false");
}
}
out.close();
}catch(Exception e){
e.printStackTrace();
}finally{
try{
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
}
}
}
----------------------------
check.jsp
<%@ page language="java" pageEncoding="utf-8"%>
<%@ page import="java.sql.*"%>
<%@ page import="java.util.*"%>
<!doctype html>
<html lang="en">
<body>
<script>
window.onload = initPage;
function initPage() {
document.getElementById("userid").onblur = checkUserid;//引用函数方法。
}
//创建请求对象
function createRequest() {
try {
request = new XMLHttpRequest();
} catch (tryMS) {
try {
request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (otherMS) {
try {
request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (failed) {
request = null;
}
}
}
return request;
}
//检查用户名是否重复
function checkUserid(){
request=createRequest();
var theName = document.getElementById("userid").value;
request.open("POST","CheckServlet?userid="+theName,true);
request.onreadystatechange=checkUseridCallback;
request.send(null);
document.getElementById("msg").innerHTML="正在验证...";
}
//回调函数
function checkUseridCallback(){
if(request.readyState==4){
if(request.status==200){
if( request.responseText=="true"){
document.getElementById("msg").innerHTML="用户ID重复";
}else{
document.getElementById("msg").innerHTML="此用户ID可以注册";
}
}
}
}
</script>
<form action="check.jsp" method="POST" >
用户ID：<input type="text" id="userid" name="userid">
<span id="msg"></span>
<br>
姓名<input type="text" name="name" >
</form>
</body>
</html>
Ajax 数据库
[解决办法]
userid作为主键的话应该用number类型。
自增。
check.jsp说还可以注册的那说明返回的就不是String类型的true或者false。
你是不是返回了boolean型的呢？
这东西好久没接触，只是觉得某些地方很怪，但是说不上来。
你想知道返回的是什么的话，那么你干嘛不在页面打出来看看呢？
