如何在Spring MVC中的同一页面上显示错误消息

Question

我正在使用表单数据在spring mvc中调用一个控制器.

在保存之前,我会检查id是否在某个范围内.如果id不在范围内,我需要在同一页面上显示一条消息The id selected is out of Range, please select another id within range.

我在互联网上找到了样本,如果出现问题,我可以将其重定向到失败的jsp.但在我的情况下如何做到这一点？

@RequestMapping(value = "/sendMessage")
public String sendMessage(@ModelAttribute("message") Message message,
        final HttpServletRequest request) { 
    boolean check = userLoginService.checkForRange(message.getUserLogin());
    if(!check){
        return "";  //What Should I do here??????
    }
}

Answer 1

一种简单的方法是将您的错误消息添加为模型属性.

@RequestMapping(value = "/sendMessage")
public String sendMessage(@ModelAttribute("message") Message message,
        final HttpServletRequest request, Model model) {

    boolean check = userLoginService.checkForRange(message.getUserLogin());
    if(!check){
        model.addAttribute("error", "The id selected is out of Range, please select another id within range");
        return "yourFormViewName";
    }
}

然后你的jsp可以显示"error"属性(如果存在).

<c:if test="${not empty error}">
   Error: ${error}
</c:if>

编辑

这是一个粗略的,未经测试的ajax验证实现.JQuery假设.

添加ajax的请求映射以命中:

@RequestMapping("/validate")
@ResponseBody
public String validateRange(@RequestParam("id") String id) {

    boolean check = //[validate the id];
    if(!check){
        return "The id selected is out of Range, please select another id within range";
    }
}

截取客户端的表单提交并验证:

$(".myForm").submit(function(event) {

    var success = true;

    $.ajax({
        url: "/validate",
        type: "GET",
        async: false, //block until we get a response
        data: { id : $("#idInput").val() },
        success: function(error) {
            if (error) {
                $("#errorContainer").html(error);
                success = false;
            }
        }
    });

    return success;

});

Answer 2

您还可以使用现有的错误消息支持.这样,您可以使用spring-mvc错误标记在全局上下文甚至在字段级别显示错误.例如,如果您假装将错误绑定到字段,则可以使用:

@RequestMapping(value = "/sendMessage")
public String sendMessage(@ModelAttribute("message") Message message, BindingResult bindingResult) {
    boolean check = userLoginService.checkForRange(message.getUserLogin());
    if (!check) {
        bindingResult.rejectValue("userLogin", "error.idOutOfRange", "The id selected is out of Range, please select another id within range");
        return "jspPage"; // path to the jsp filename, omit extension (considering default config) 
    }
}

在页面级别,您可以执行以下操作:

<form:form method="POST" commandName="message">
    ...
    <form:input path="userLogin" />
    <form:errors path="userLogin" />
    ...
</form:form>

如果您只想显示全局错误,请在bindingResult.rejectValue和form:errors标记处省略参数名称.

注意:您无需担心手动恢复参数.在正常情况下,spring-mvc会为您处理.

希望能帮助到你.