function getXMLHttpRequest() {
        var xmlhttp;
		if (window.XMLHttpRequest) {
			try {
				xmlhttp = new XMLHttpRequest();
				xmlhttp.overrideMimeType("text/html;charset=UTF-8");//设定以UTF-8编码识别数据
			} catch (e) {}
		} else if (window.ActiveXObject) {
			try {
				xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				try {
					xmlhttp = new ActiveXObject("Msxml2.XMLHttp");
				} catch (e) {
					try {
						xmlhttp = new ActiveXObject("Msxml3.XMLHttp");
					} catch (e) {}
				}
			}
		}
        return xmlhttp;
}// JavaScript Document


function check(logform){
	if(document.logform.user.value==""){
		alert('请输入用户名');
		return false;
	}
	if(document.logform.pass.value == "" ){
		alert('请输入密码')
		return false;
	}
	if(document.logform.validate.value == ""){
		alert('请输入验证码');
		return false;
	}

	return true;
	
}