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File Upload Using AngularJS and Spring

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File Upload Using AngularJS and Spring

In this article, we discuss how to use these two popular frameworks to pull in data from an external source and use it to populate the backend of our web app.

· Web Dev Zone
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Hi, everyone!

Over the past few days, several people have asked me how to create a SPRING-MVC file upload using AngularJS. So I thought I'd write a post about it where I create working code that fetches a multipart file from the front-end and process this data in the backend.

To begin, you need to know the basics of AngularJS and RESTful Web Services.

The project is going to be created using the Maven Build Tool. So you may need to know the basics of MAVEN too. If not, then you don't need to worry. Install the jar externally and run it with the build tool you like (ANT, etc).

Let's Begin:

Here are the dependencies in POM.XML that are needed for our code. If you're not using Maven, then download the “Apache common” JARs externally. Here is an easy way to do it. Go to this URL and download the commons-io dependency jar. Inside that, you can search the artifactId mentioned in the POM.XML and can fetch the required JAR from that site.

<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3</version>
</dependency>

<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.4</version>
</dependency>

Now, we will create a bean to add the maximum file upload limit. Here is the code for that. Place this in Spring configuration XML. This file is more commonly called SPRING-SERVLET.XML

Now, let's create a controller for fetching the file from the frontend and to process that file and store it in a specified path. Here is a code for that:

@RequestMapping(value = "/fileUpload", method = RequestMethod.POST)
@Produces(MediaType.APPLICATION_JSON) 
public Data continueFileUpload(HttpServletRequest request, HttpServletResponse response){
        MultipartHttpServletRequest mRequest;
String filename = "upload.xlsx";
try {
   mRequest = (MultipartHttpServletRequest) request;
   mRequest.getParameterMap();

   Iterator itr = mRequest.getFileNames();
   while (itr.hasNext()) {
        MultipartFile mFile = mRequest.getFile(itr.next());
        String fileName = mFile.getOriginalFilename();
        System.out.println(fileName);

        java.nio.file.Path path = Paths.get("C:/Data/DemoUpload/" + filename);
        Files.deleteIfExists(path);
        InputStream in = mFile.getInputStream();
        Files.copy(in, path);
 }
   } catch (Exception e) {
        e.printStackTrace();
   }
return null;
}

Here I am storing that EXCEL FILE in “C:/Data/DemoUpload/” with a modified filename (upload.xlsx). This uses two items: one is fetching the file as a map using MultipartHttpServletRequest, and one is saving that file using the Input stream buffer. This will copy the file that was created and put it into the place that we specify.

Now let's create a front-end for clients. Here is a simple script for it:

<div>
 <div class="jumbotron"><input type="file" /> <button>upload me</button></div>
 &nbsp;
 <div class="alert alert-danger fade in"><a class="close" href="#" data-dismiss="alert">×</a> <strong>Errors!</strong> {{errors.value}}</div>
 </div>
 <script>
 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.service('fileUpload', ['$q','$http', function ($q,$http) {
 var deffered = $q.defer();
 var responseData;
 this.uploadFileToUrl = function(file, uploadUrl){
 var fd = new FormData();
 fd.append('file', file);
 return $http.post(uploadUrl, fd, {
 transformRequest: angular.identity,
 headers: { 'Content-Type' : undefined}
 })
 .success(function(response){

/* $scope.errors = response.data.value; */
   console.log(response);
   responseData = response;
   deffered.resolve(response);
   return deffered.promise;
   })
   .error(function(error){
   deffered.reject(error);
   return deffered.promise;
   });

}

this.getResponse = function() {
 return responseData;
 }

}]);

myApp.controller('myCtrl', ['$scope', '$q', 'fileUpload', function($scope, $q, fileUpload){
 $scope.dataUpload = true;
 $scope.errVisibility = false;
 $scope.uploadFile = function(){
     var file = $scope.myFile;
     console.log('file is ' );
     console.dir(file);

      var uploadUrl = "<give-your-url>/continueFileUpload";
       fileUpload.uploadFileToUrl(file, uploadUrl).then(function(result){
       $scope.errors = fileUpload.getResponse();
       console.log($scope.errors);
       $scope.errVisibility = true;
       }, function(error) {
       alert('error');
       })

};
 }]);
 </script>

Here we created a directive and a service for fetching the data and putting it in the backend. We used $q for asynchronous calls. This is called a PROMISE in AngularJS. In our next course, I will surely describe how to create promises and what asynchronous calls are. Change the “ ” place with your server URL and run the code to upload an Excel sheet to your backend.

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Topics:
spring 4 ,rest api ,angularjs ,web dev

Published at DZone with permission of Vishal Srinivasan. See the original article here.

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