AJAX之开发范例介绍
日期：2014-05-16 浏览次数：20670 次
AJAX之开发实例介绍
<html>
<head>
<title>www.MLDNJAVA.cn</title>
<script language="javascript">
var xmlHttp ;
function createXMLHttp(){ //AJAX创建代码
if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest(); //firefox浏览器内核
} else {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
}
function checkUserid(userid){
createXMLHttp();
xmlHttp.open("POST","CheckServlet?userid="+userid);
xmlHttp.onreadystatechange = checkUseridCallback
xmlHttp.send(null);
document.getElementById("msg").innerHTML = "正在验证...";
}
function checkUseridCallback(){
if(xmlHttp.readyState == 4){
if(xmlHttp.status == 200){
alert("************");
var text = xmlHttp.responseText;
if(text == "true"){
document.getElementById("msg").innerHTML = "用户ID重复，无法使用!";
} else {
document.getElementById("msg").innerHTML = "此用户ID可以注册!";
}
}
}
}
</script>
</head>
<body>
<form action="regist.jsp" method="post">
用户ID： <input type="text" name="userid" onblur="checkUserid(this.value)"><span id="msg"></span><br>
姓 名：<input type="text" name="name"><br>
密 码 <input type="password" name="password"><br>
<input type="submit" value="注册">
<input type="reset" value="重置">
</form>
</body>
</html>
?
?2,CheckServlet.java
?
package org.lxh.ajaxdemo;
import java.sql.* ;
import java.io.* ;
import javax.servlet.* ;
import javax.servlet.http.* ;
public class CheckServlet extends HttpServlet{
public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
public static final String DBURL = "jdbc:mysql://localhost:3306/mldn";
public static final String DBUSER = "root" ;
public static final String DBPASS = "123456" ;
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");
try {
Class.forName(DBDRIVER);
conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
String sql = "SELECT COUNT(userid) FROM user WHERE userid=?";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1,userid);
rs = pstmt.executeQuery();
if(rs.next()){
if(rs.getInt(1) > 0){
out.print("true");
} else {
out.print("false");
}
}
System.out.println("**********************");
}catch(Exception e){
e.printStackTrace();
}finally {
try
{
conn.close();
}
catch (Exception e) { }
}
}
};
?
2,CityServlet.java?
package org.lxh.ajaxdemo ;
import java.io.* ;
import org.w3c.dom.* ;
import javax.xml.parsers.* ;
import javax.xml.transform.* ;
import javax.xml.transform.dom.* ;
import javax.xml.transform.stream.* ;
import javax.servlet.* ;
import javax.servlet.http.* ;
public class CityServlet extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
this.doPost(request,response) ;
}
public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
response.setContentType("text/xml;charset=GBK") ;
PrintWriter out = response.getWriter() ;
ByteArrayOutputStream bos = new ByteArrayOutputStream() ;
try{
Docum
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