使用Ajax进行用户名动态校验，局部属性页面
1.在HTML页面中使用js脚本将请求数据发送给后台servlet
- 由按钮触发校验事件
<input type="text" name="check" onblur="checkUsername(this.value)">
- 相应的处理脚本
var req = new XMLHttpRequest();
function checkUsername(name){
req.open("POST","/javaweb/servlet/CheckNameServlet",true);
req.setRequestHeader("Content-type","application/x-www-form-urlencoded");
req.onreadystatechange=callback;
req.send("username="+name);
}
2.后台将获取的数据进行校验，将结果返回给前台
public void doPost(HttpServletRequest request,HttpServletResponse response) throws Exception {
String username = request.getParameter("username");
MyService service = new MyService();
boolean result = service.checkName(username);
response.setContentType("text/plain");
response.setHeader("Cache-control","no-cache");
PrintWriter out = response.getWriter();
if(rseult){
out.write("用户名可以使用");
}
else{
out.write("用户名已被占用");
}
out.flush();
out.close();
}
3.刷新局部页面
function callback(){
if(req.readyState==4&&req.status==200){ alert(req.responseText); }
}