使用Dropzone上传图片及回显示例

一、图片上传所涉及到的问题
1、HTML页面中引入这么一段代码

    <div class="row">

        <div class="col-md-12">

            <form dropzone2  class="dropzone" enctype="multipart/form-data" method="post"></form>

        </div>

    </div>

2、 在指令中发送POST请求
关键代码如下

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

    manage.directive('dropzone2', function () {
        return {
            restrict: 'EA',
            controller: ['$scope', '$element', '$attrs', '$timeout', function ($scope, $element, $attrs, $timeout) {
                $element.dropzone({
                    url : "rest/components/"+$scope.component.name+"/"+$scope.component.version+"/images",
                    autoDiscover : false,
                    autoProcessQueue: true,
                    addRemoveLinks: true,
                    addViewLinks: true,
                    acceptedFiles: ".jpg,.png",
                    dictDefaultMessage: "upload head picture",
                    maxFiles : "1",
                    dictMaxFilesExceeded: "Only can upload one picture, repeat upload will be deleted!",
                    init: function () {
                     var mockFile = { name: "Filename", 
                                      size: 10000
                                     };
                     this.emit("addedfile", mockFile);
                     mockFile._viewLink.href = "rest/components/"+$scope.component.name+"/"+$scope.component.version +"/"+$scope.component.image;
                     mockFile._viewLink.name = $scope.component.image;
                     this.emit("thumbnail", mockFile, "rest/components/"+$scope.component.name+"/"+$scope.component.version +"/"+$scope.component.image);
                     this.emit("complete", mockFile);


                        $(".dz-view").colorbox({
                               rel:'dz-view', 
                               width:"70%",
                               height:"80%"
                        });

                        this.on("error", function (file, message) {
                            alert(message);
                            this.removeFile(file);
                        });
                        this.on("success", function(file,imageInfo) {

                          file._viewLink.href = imageInfo.newfile;
                          file._viewLink.name = imageInfo.newfile;

                           $scope.$apply(function() {
                                $scope.component.image="rest/components/"+$scope.component.name+"/"+$scope.component.version+"/"+imageInfo.newfile;
                           });

                        });
                        this.on("removedfile", function(file) {
                           var removeFileUrl = file._viewLink.name;

                                if($scope.component.image == removeFileUrl){
                                    this.removeFile(file);
                                }

                          });

                    }
                });

            }]
        };
    });

注意上述URL的请求方式，要在Angular模拟请求中放行。格式如下：

var hubMock = angular.module('hubMock', ['ngMockE2E']);

    hubMock.run(['$httpBackend', '$http', function ($httpBackend, $http) {


        $httpBackend.whenGET(/\.html/).passThrough();
        $httpBackend.whenGET(/\.json/).passThrough();

        $httpBackend.whenPOST(/rest\/components\/.+\/.+\/images/).passThrough();

    }]);

$httpBackend.whenPOST(/rest\/components\/.+\/.+\/images/).passThrough(); 放行图片上传发送是POST 请求。

3、处理上传图片的请求将其存储在本地

 @POST
    @Path("/{componentName: \\w+}/{version: \\d\\.\\d\\.\\d}/images")
    @Produces(MediaType.APPLICATION_JSON)
    public Response uploadMyComponentImage(@Context HttpServletRequest request, @PathParam("componentName") String componentName,
            @PathParam("version") String version) {
        Map<String, String> infoMap = componentService.uploadMyComponentImage(request, componentName, version);

        return Response.ok(infoMap).build();
    }

4、通过接口及其实现类来处理图片上传的位置

  @Override
    public Map<String, String> uploadMyComponentImage(HttpServletRequest request, String componentName, String version) {

        Map<String, String> infoMap = new HashMap<String, String>();
        String url = null;
        try {
            url = application.getStorageLocation(File.separator + componentName + File.separator + version).getAbsolutePath();
        } catch (IOException e1) {
            e1.printStackTrace();
        }

        DiskFileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);

        try {

            Map<String, List<FileItem>> items = upload.parseParameterMap(request);

            for (Entry<String, List<FileItem>> entry : items.entrySet()) {

                String key = entry.getKey();

                Iterator<FileItem> itr = items.get(key).iterator();

                while (itr.hasNext()) {

                    FileItem item = itr.next();
                    String newfileName = UUID.randomUUID().toString() + "-" + item.getName();

                    infoMap.put("newfile", "" + newfileName);

                    File file = new File(url);
                    if (!file.exists()) {
                        file.mkdirs();
                    }
                    file = new File(url + File.separator + "img" + File.separator + newfileName);
                    item.write(file);

                }
            }

        } catch (FileUploadException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return infoMap;
    }

在这里返回的是一个map, key是newfile,value是”” + newfileName，因此在上传成功后就可以取得图片的信息，如下示例 imageInfo.newfile;：

 this.on("success", function(file,imageInfo) {

                          file._viewLink.href = imageInfo.newfile;
                          file._viewLink.name = imageInfo.newfile;

                           $scope.$apply(function() {
                                $scope.component.image="rest/components/"+$scope.component.name+"/"+$scope.component.version+"/"+imageInfo.newfile;
                           });

                        });

二、页面中的图片如何进行回显？

1、现今的网站上图片上的获取方式主要是以Get请求的方式传回图片流到浏览器端，这里同样采用请求主动获取图片的方式。

页面回显时会主动发送请求：

“rest/components/”+ scope.component.name+"/"+ scope.component.version +”/”+$scope.component.image

真实请求路径是这样的：

localhost:8080/xxxxxx/rest/components/2_component1/1.0.0/0c6684ad-84df-4e0e-8163-9e2d179814e6-Penguins.jpg

2、后台如何接受请求，处理请求呢？
参见以下代码，返回到浏览器的实际上就是一个输出流。

关键代码示例

 /** * get pictures OutputStream * * @param componentName * @param version * @return */
    @GET
    @Path("/{componentName: \\w+}/{version: \\d\\.\\d\\.\\d}/{imagePath: .+}")
    @Produces(MediaType.APPLICATION_OCTET_STREAM)
    public Response findImages(@PathParam("componentName") final String componentName, @PathParam("version") final String version,
            @PathParam("imagePath") final String imagePath) {
        StreamingOutput output = new StreamingOutput() {

            private BufferedInputStream bfis = null;

            public void write(OutputStream output) throws IOException, WebApplicationException {

                try {
                    String filePath = "";
        //判断图片的请求路径是否长路径，这个根据需求而来的
                    if (imagePath.contains("/")) {
                    //取出图片
                        filePath = application.getStorageLocation(File.separator + componentName + File.separator + version) + File.separator + "img"
                                + File.separator + imagePath.split("/")[imagePath.split("/").length - 1];

                    } else {
                      //取出图片
                        filePath = application.getStorageLocation(File.separator + componentName + File.separator + version) + File.separator + "img"
                                + File.separator + imagePath;

                    }

                    bfis = new BufferedInputStream(new FileInputStream(filePath));
                    int read = 0;
                    byte[] bytes = new byte[1024];
                    while ((read = bfis.read(bytes)) != -1) {
                        output.write(bytes, 0, read);
                    }

                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    try {
                        if (bfis != null) {
                            bfis.close();
                        }
                        output.flush();
                        output.close();
                    } catch (Exception e2) {
                        e2.printStackTrace();
                    }
                }

            }

        };
        //返回给浏览器
        return Response.ok(output, MediaType.APPLICATION_OCTET_STREAM).build();

    }

3、当点击view时，又会去请求后台返回预览大图图像，这里使用了colorbox插件来进行大图像的预览和轮播显示，感觉很酷的样子。

效果如下所示：