cellspacing="0">

//创建XMLHttpRequest对象

function GetO()

{

var ajax=false;

try

{

ajax = new ActiveXObject("Msxml2.XMLHTTP");

}

catch (e)

{

try

{

ajax = new ActiveXObject("Microsoft.XMLHTTP");

}

catch (E)

{

ajax = false;

}

}

if (!ajax && typeof XMLHttpRequest!='undefined')

{

ajax = new XMLHttpRequest();

}

return ajax;

}

function getMyHTML(serverPage, objID) {

var ajax = GetO();

//得到了一个html元素，在下面给这个元素的属性赋值

var obj = document.all[objID];

//设置请求方法及目标，并且设置为异步提交

ajax.open("post", serverPage, true);

ajax.onreadystatechange = function()

{

if (ajax.readyState == 4 && ajax.status == 200)

{ //ajax.responseText是服务器的返回值，把值赋给id=passport1的元素的属性

//innerHTML这个属性或说这个变量表示一组开始标记和结束标记之间的内容

obj.innerHTML = ajax.responseText;

}

}

//发送请求

ajax.send(null);

}

function CheckGroupName()

{

getMyHTML("http://13.1.1.51:8080/ajax/check.jsp?groupName="+name_form.group_name.value, "passport1");

}

//这个函数的作用是当用户的焦点从其他地方回到group_name这个输入框时再给属性赋回原内容

function sl(tx)

{

if(tx=='passport1')

{

document.all[tx].innerHTML = "

}

}

function check()

{

if(document.name_form.group_name.value.length<1)

{

alert("请您给您的群组取个名字！");

document.name_form.group_name.focus();

return false;

}

if(!OK())

{

return false;

}

document.name_form.action='addgroup.do';

document.name_form.target='_parent';

document.name_form.submit();

}

function OK()

{

var obj = document.getElementById("passport1");

if(obj.innerHTML.indexOf("可用")==-1)

{

return false;

}

return true;

}

class="text12black">

value="" size=30 maxlength="50" onBlur="javaScript:CheckGroupName();"

onFocus="return sl('passport1');" />

jsp后台处理  check.jsp

String action = "";

String groupname = "";

// 检查用户名

// 用作数据库联接，可以根据你的情况修改，如果为测试可以不用*作记号的语句

InitialContext ctx = null;

DataSource ds = null;

Connection conn = null;

Statement stmt = null;

ResultSet rs = null;

try {

action = request.getParameter("action");

groupname = request.getParameter("groupName").trim();

if ("".equals(groupname)) {

System.out.println("null");

out.println("

} else if (groupname.length() < 4 || groupname.length() > 20) {

out.println("

} else {

ctx = new InitialContext();

ds = (DataSource) ctx.lookup("java:/student");

conn = ds.getConnection();

stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,

ResultSet.CONCUR_READ_ONLY);

String strsql = "select userinfo_name from personal_userinfo where userinfo_name='"

+ groupname + "'";

rs = stmt.executeQuery(strsql);

if (rs.next()) {

out.println("

} else {

out.println("您的用户名可用");

}

}

} catch (Exception e) {

System.out.println(request.getServletPath() + " error : "

+ e.getMessage());

} finally {

if (rs != null)

rs.close();

if (stmt != null)

stmt.close();

if (conn != null)

conn.close();

}

%>