如何用AJAX 获取后台验证码问题（急啊）

[达人游戏男孩]

//这是后台验证码的代码(方法)
@RequestMapping(method = RequestMethod.POST)
public String register(User user, HttpServletRequest request, HttpSession session, RedirectAttributes redirectAttributes) {
if (!beanValidator(user)) {
return this.paramErrorJsonString();
}
String validCode = request.getParameter("code");
if (StringUtils.isNotEmpty(validCode)) {
String code = (String) session.getAttribute(ValidateCodeServlet.VALIDATE_CODE);
if (!StringUtils.equals(validCode, code)) {
return "{\"ret\":-99,\"msg\":\"驗證碼失敗\"}";
}
}
}

//JS 部分
function check_code(code){
var valid_code=document.getElementById('code').value;
if (valid_code!=validCode)
{
showInfo("agreement_code",code_notice);
change_submit("true");//禁用提交按
validateFail(7);
}
else
{
showInfo("agreement_code",info_can);
validateSucc(7);//允许提交按
}
}

//JSP 部分
<input type="text" name="code" id="code" class="inputCode" onBlur="check_code(this)" placeholder=" 验证码" maxlength="10"
style="width:95px;height:30px; border:#ccc solid 1px;"/>
<font size=2><SPAN id="agreement_code" class="register_code"></SPAN></font>
<img src="${pageContext.request.contextPath}/servlet/validateCodeServlet" class="mid ${name}"/>

<TD><LABEL>

[LifeAndGame]

出神马问题了？