Ajax提交数据判断员工编号是否存在，及自动填充与员工编号所对应的员工姓名。

JSP页面中所需要的JavaScript事件及Ajax

 1 <script type="text/javascript">
 2 function checkEmpNo(id){
 3     var empNoValue=document.getElementById(id).value;
 4         $.ajax({
 5         type:‘post‘,
 6             url:‘employee_checkEmpNoAndEmpName.htm‘,
 7             data:‘empNo=‘+empNoValue,
 8             success: function(result){
 9                 if(result=="该用户名不存在！"){
10                    alert("该用户名不存在！");
11                    document.getElementById(id).value="";
12                    document.getElementById("empName").value="";
13                    document.getElementById(id).focus();
14                 }else{
15                    document.getElementById("empName").value=result;
16                    document.getElementById("entranceStart").focus();
17                 }
18     });
19 </script>
20 <form>
21 　　<table>
22 　　　　<tr>
23 　　　　　　<td><input id="empNo" onblur="checkEmpNo(this.id)" type="text" name="empNo" /></td>
24 　　　　　　<td><input id="empName" type="text" name="empName" /></td>
25 　　　　</tr>
26 　　</table>
27 </form>        

后台Action所需的代码：

public clasee empAction extends ActionSupport{
public String checkEmpNoAndEmpName() throws Exception {
        HttpServletRequest request = ServletActionContext.getRequest();
        HttpServletResponse respons = ServletActionContext.getResponse();
        String empNo = request.getParameter("empNo");//获取页面提交给后台的Action的empNo
        respons.setContentType("text/html;charset=utf-8");//对响应的字符集进行设置
        String sendStr = "";
        List<EmployeeInfo> employeeInfoList = this.empService.checkEmpNo(empNo);//调用业务根据empNo层查询此用户
        try {
            PrintWriter out=respons.getWriter();//多去打印对象
            if (employeeInfoList.size()>0) {
                sendStr = employeeInfoList.get(0).getEmpName();
            } else {
                sendString = "该用户名不存在！";
            }
            out.print(sendStr);//将后台动态sendStr输出到JSP页面
            out.flush();
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }
}