Using Multipart without Form in Spring MVC

Question

I had gone through many articles in stackoverflow on this specific topic, after a detailed analysis I have finally dared to post another question on the same topic.

I think this would be obvious that what I wanted to do here,

What do I want?

I want to upload a file. I am using angularjs and Spring MVC.

Source :

Controller @Spring :

@RequestMapping(value="/upload", method=RequestMethod.POST, consumes = {"multipart/form-data"})
public String handleFileUpload(@RequestParam(value = "file") MultipartFile file){
    String name="";
    if (!file.isEmpty()) {
        try {
            byte[] bytes = file.getBytes();
            BufferedOutputStream stream =
                    new BufferedOutputStream(new FileOutputStream(new File(name)));
            stream.write(bytes);
            stream.close();
            return "You successfully uploaded " + name + "!";
        } catch (Exception e) {
            return "You failed to upload " + name + " => " + e.getMessage();
        }
    } else {
        return "You failed to upload " + name + " because the file was empty.";
    }
}
@Bean
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        multipartResolver.setMaxUploadSize(500000000);
        return multipartResolver;
    }

HTML :

File to upload: <input type="file"
            file-model="file" name="fd"><br /> Name: <input type="text" name="name"><br />
        <br /> <input type="submit" ng-click="uploadFile()" value="Upload"> Press here to
        upload the file!

JS :

$scope.uploadFile = function() {
    var fd = new FormData();
    var file = $scope.file;
    fd.append('file', file);
    $http.post("/upload",fd,
            {
                headers : {
                    'Content-Type' : undefined
                }
            }).success(function(data) {
        debugger;
    }).error(function(data) {
        debugger;
    })
}

Looks fair??? Here are the observations

Observations on execution:

References :

Spring MVC - AngularJS - File Upload - org.apache.commons.fileupload.FileUploadException

Javascript: Uploading a file... without a file

What is the boundary parameter in an HTTP multi-part (POST) Request?

And many more....:)

---

Update

Directive which is used in angular,

myApp.directive("fileread", [function () {
    return {
        scope: {
            fileread: "="
        },
        link: function (scope, element, attributes) {
            element.bind("change", function (changeEvent) {
                var reader = new FileReader();
                reader.onload = function (loadEvent) {
                    scope.$apply(function () {
                        scope.fileread = loadEvent.target.result;
                    });
                }
                reader.readAsDataURL(changeEvent.target.files[0]);
            });
        }
    }
}]);

Request extracted from chrome :

Answer 1

Problem in my approach :

I created a bean for MultiPartResolver. My understanding after resolving the issue is like you define this bean only when you want a specific type of file or something very specific to the application. Although I seek more insight into this and would love to hear from techies of stackoverflow.

Solution for current problem:

I would give my source code,

HTML :

<div ng-controller="myCtrl">
        <input type="file" file-model="myFile" />
        <button ng-click="uploadFile()">upload me</button>
    </div>

AngularJS :

     var myApp = angular.module('myApp', []);

        myApp.directive('fileModel', ['$parse', function ($parse) {
            return {
                restrict: 'A',
                link: function(scope, element, attrs) {
                    var model = $parse(attrs.fileModel);
                    var modelSetter = model.assign;

                    element.bind('change', function(){
                        scope.$apply(function(){
                            modelSetter(scope, element[0].files[0]);
                        });
                    });
                }
            };
        }]);
        myApp.controller('myCtrl', ['$scope', '$http', function($scope, $http){

            $scope.uploadFile = function(){
                var file = $scope.myFile;
                var fd = new FormData();
                fd.append('file', file);
    //We can send anything in name parameter, 
//it is hard coded to abc as it is irrelavant in this case.
                var uploadUrl = "/upload?name=abc";
                $http.post(uploadUrl, fd, {
                    transformRequest: angular.identity,
                    headers: {'Content-Type': undefined}
                })
                .success(function(){
                })
                .error(function(){
                });
            }

        }]);

Spring :

@RequestMapping(value="/upload", method=RequestMethod.POST)
    public String handleFileUpload(@RequestParam("name") String name,
            @RequestParam("file") MultipartFile file){
        if (!file.isEmpty()) {
            try {
                byte[] bytes = file.getBytes();
                BufferedOutputStream stream =
                        new BufferedOutputStream(new FileOutputStream(new File(name)));
                stream.write(bytes);
                stream.close();
                return "You successfully uploaded " + name + "!";
            } catch (Exception e) {
                return "You failed to upload " + name + " => " + e.getMessage();
            }
        } else {
            return "You failed to upload " + name + " because the file was empty.";
        }
    }

And @arahant Even though we don't see any document base64 content in the request payload while sending request, angular does send MultiPartFile, here is the screenshot

Thanks to all the references. If not for these people I wouldn't have solved this problem at all.

References :

http://uncorkedstudios.com/blog/multipartformdata-file-upload-with-angularjs

Answer 2

Using MultipartHttpServletRequest would be a simple option here, which should work without any other change.

public String handleFileUpload(MultipartHttpServletRequest request) {
    Map<String, MultipartFile> uploadedFiles = request.getFileMap();
    //...
}