java - Angularjs 将文件多部分 FormData 中的空值传递给 Spring MVC

Question

我正在尝试将带有多部分数据(图像)的表单数据发送到 Spring MVC Controller 。从我的表格来看。图像字段不是强制性的。因此，当我在没有输入图像字段的情况下调用 spring Controller 时，我在浏览器控制台中收到以下错误。

Failed to load resource: the server responded with a status of 400 (Bad Request)

HTML 代码:

<input file="file" type="file" id ="file2"/>

AngularjS 代码:

$scope.saveData = function (formObj) {
    $http({
        url: CONTEXT_PATH+'saveFile',
        method: "POST",
        headers: { 'Content-Type': undefined },
        transformRequest: function (data) {
            alert(data.files);
            var formData = new FormData();
            formData.append("model", angular.toJson(data.model));
            formData.append("file", data.files);
            return formData;
        },
        data: { model: formObj, files: $scope.file }
    }).then(function (response) {
        //alert(response);
    });
};


app.directive('file', function () {
    return {
        scope: {
            file: '='
        },
        link: function (scope, el, attrs) {
            el.bind('change', function (event) {
                var file = event.target.files[0];
                scope.file = file ? file : undefined;
                scope.$apply();
            });
        }
    };
});

Spring Controller 代码:

@RequestMapping(value = "/saveFile")
public @ResponseBody String storeAd(@RequestParam ("model") String adString, @RequestParam ("file") MultipartFile file) throws IOException {
    System.out.println("adString > "+adString);
    return "OK";
}

Answer 1

当图像未上传时，请求是错误的，因为除非另有定义，否则 Spring MVC 假定所有必需的参数。对于您的情况，您应该添加 required = false。

@RequestParam(value = "file", required = false)