Action:
private String uname;
private String upwd;
@Override
public String execute() throws Exception {
HttpServletResponse response = ServletActionContext.getResponse();
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
if ("lwq".equals(uname)) {
out.print("error");
} else {
out.print("success"); //最后由responseText获取
}
out.close();
return null;
}
JSP:
<form action="<%=basePath%>login.action">
<p>
<input type="text" name="uname" id="uname"
onblur="checkName(this.value)">
</p>
<p>
<input type="text" name="upwd" id="upwd">
</p>
<span id="nameMessage"></span>
</form>
JS AJAX:
<script type="text/javascript">
var ajax;
/* 创建XMLHttpRequest对象 */
function creatXMLHttpRequest() {
if (window.XMLHttpRequest) {
ajax = new XMLHttpRequest(); //JS第二定律
} else {
ajax = new ActiveXObject("Microsoft.XMLHTTP");
}
}
/* 到服务器检查用户是否存在 */
function checkName(uname) {
creatXMLHttpRequest(); //调用方法 初始化ajax变量
ajax.open("get", "<%=basePath%>login.action?uname=" + uname, true);
//传递三个参数 提交方法 url 是否异步请求
ajax.send(null);
ajax.onreadystatechange = callback;
}
/* 对相应结果进行处理 */
function callback() {
if(ajax.readyState==4) //状态 等于四时 表示读取完毕
{
if(ajax.status==200) //status等于200表示服务器无错
{
if(ajax.responseText=="success"){
document.getElementById("nameMessage").innerHTML="正确";
}else{
document.getElementById("nameMessage").innerHTML="已存在";
}
}
}
}
</script>
JS学的不咋好 估计Ajax这块要够呛了
转载于:https://www.cnblogs.com/MonkeyJava/p/10807419.html