以前写过的一个简单的AJAX程序

function createXHR() { var xhr; try { xhr = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } catch (E) { xhr = false; } } if (!xhr && typeof XMLHttpRequest != "undefined") { xhr = new XMLHttpRequest(); } return xhr; } var req; function checkInput() { var flag; var operatorId = $('operatorId').value; var patrn = /^[a-zA-Z]{1}[0-9]{9}$/; if (!patrn.exec(operatorId)) { flag = false; } else { flag = true; } if (flag == false) { $('newOperatorIdMsg').innerHTML = "<font color='red'>输入有误！用户名必须为10位，且首位为字母!</font>"; } else { var url = "addOperator?operatorId=" + operatorId +"&now=" + new Date(); req = createXHR(); req.open("get", url); req.onreadystatechange = handleRequest; req.send(null); } } function handleRequest() { var checkResult = $('newOperatorIdMsg'); if (req.readyState == 4) { if (req.status == 200) { var str = req.responseText; if (str == 0) { checkResult.innerHTML = "<font color='green'>此Id未被使用，可以添加！</font>"; } else if (str == 1) { checkResult.innerHTML = "<font color='red'>此Id已经被占用，请更换id！</font>"; } } } }   

 

 

var str = req.responseTest;

         捕获Servlet（或其他，如action）中out.println（“”）得来的数据。

 

当然，我还应当学学，捕获xml的数据……