如何在struts框架下使用ajax验证用户名密码

 1、下载一个ajax框架包prototype.js

 2、在jsp页面写

        function valid() {
        if(document.forms[0].loginid.value!=document.forms[0].orginLoginid.value){
        document.getElementById('echo1').innerHTML = "正在检测登录ID...";
        var ajax = new Ajax.Request('/bankInfoAction.do', {method: 'get',parameters:'mode=equalLoginId&loginid=' + document.forms    [0].loginid.value,onComplete:callback2});
        }
        else{
            document.getElementById('echo1').innerHTML = "";
        }
        }
function callback2(originalRequest) {
        if (originalRequest)
            if (originalRequest.readyState == 4) {
                if (originalRequest.status == 200) {
                    if (originalRequest.responseText == "1") {
                        $('echo1').innerHTML = "该登录ID可以使用！";
                    } else {
                        $('echo1').innerHTML = "<font color=red>该登录ID已存在或不可用！</font>";
                        var logid=document.forms[0].loginid.value;

                        document.forms[0].loginid.value = "";
                        document.forms[0].password.value = "";
                        document.forms[0].password1.value = "";
                        if(logid!=""){
                        document.forms[0].loginid.focus();
                        }
                    }
                }
            }
}

 3、在action的execute方法里调用。返回的是xml值，如这里的1，0.前台通过0，1判断是否存在ID

 if (bankInfoForm.getFlag() == -9) {//这里是判断是否存在，可在command方法里写
                write(response, "0", "text/xml", "UTF-8");
              } else {
                write(response, "1", "text/xml", "UTF-8"); // 
              }