alert(XMLHttpRequest.status);    0
                 alert(XMLHttpRequest.readyState); 0
                 alert(textStatus); error
 我配置了json转换器
//增加请假申请
@RequestMapping("/insertLeave.do")
@ResponseBody
public JsonModel  insertLeave(Leaveapply leaves, HttpSession session,Model model){

user user = (com.bdqn.entity.user) session.getAttribute("loginUser");
if(service.insertLeave(user, leaves)){
return new JsonModel("success");
}
return new JsonModel("error");

json转换器
<!-- JSON 配置 -->
  <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <list>
            <!--json视图拦截器,读取到@ResponseBody的时候去配置它-->
            <ref bean="mappingJacksonHttpMessageConverter"/>
        </list>
    </property>
</bean>
           <!--json转化器,它可以将结果转化-->
<bean id="mappingJacksonHttpMessageConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
    <property name="supportedMediaTypes">
        <list>
            <value>application/json;charset=UTF-8</value>
        </list>
    </property>
</bean>