注册用户判断是否重复

注册用户判断是否重复时用onblue事件触发脚本交互数据库并返回

js写法：

function createXmlHttpRequest(){
if(window.ActiveXObject){
return new ActiveXObject("Microsoft.XMLHTTP");
}else if(window.XMLHttpRequest){
return new XMLHttpRequest();
}
}

var xmlHttp;
function checkId(){
var uId = document.getElementById("uId").value;
var url = "sysUserManage/userManage_checkUId.action?uId="+uId;
xmlHttp = createXmlHttpRequest();
xmlHttp.onreadystatechange = processRequest;
xmlHttp.open("POST",url,true);
xmlHttp.send(null);

}

function processRequest(){
if(xmlHttp.readyState==4 && xmlHttp.status==200){
var msg = document.getElementById("msg");
if(xmlHttp.responseText == "用户名已存在!"){
msg.innerHTML=xmlHttp.responseText;
document.getElementById("uId").focus();
return false;
}else{
msg.innerHTML="";
return true;
}
}
}

后台：

public void checkUId(){
if(request.getParameter("uId") != null && !request.getParameter("uId").equals("")){
String uId = request.getParameter("uId");
List<SysUsers> list = sysUserService.queryBySQL("from SysUsers where UId = '" + uId + "'");
if(list.size()>0){
PrintWriter out=null;
try {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
out = response.getWriter();
}
catch (IOException e) {
e.printStackTrace();
}
// ActionContext.getContext().put("utopicList", utList);
out.print("用户名已存在!");
}
}
}