上传文件或者图片到服务器端

html部分：

<input type="file" accept="image/png,image/jpeg"   ng-model="img"  id="img" />

js部分：

$scope.postFile = function(data, url) {
        var deferred = $q.defer();
        $http({
                url: url,
                data: data,
                method: "post",
                transformRequest : angular.identity,
                headers: {
                     'Content-Type' : undefined//设置为undefined，会自动识别问formdata
                },
                eventHandlers: {
                    progress: function(c) {
                            console.log('total -> ' + c.total+"loaded" + c.loaded);
                            console.log(c);
                        }
                },
                uploadEventHandlers: {//查看进度
                    progress: function(e) {
                         if(e.lengthComputable) {
                              var percentComplete = e.loaded / e.total;
                              console.log("上传进度"+(percentComplete*100)+"%");
                         }else {
                             console.log("error!");
                         }
                    }
                }
            })
            .then(
                function(response) {
                    deferred.resolve(response.data);
                },
                function(response) {
                    deferred.reject(response);
                }
            );
        return deferred.promise;
    }
    //预览图片
    $scope.preview = function() {
        var ewm_preview = document.getElementById('img').files[0];
        if(window.FileReader) {
            var fr = new FileReader();
            fr.onload = function(evt) {
                $scope.ewm_pre_url = evt.target.result;
                $('.preview_img').attr('src',evt.target.result);//预览图片元素
            }
            fr.readAsDataURL(ewm_preview);
        }
    }
    $scope.ewm_update_param = {
        "name":"",
        "type":"",
        "file":document.getElementById('img').files[0]
    }
    var formdata = new FormData();
        for(var key in $scope.ewm_update_param) {
            formdata.append(key,$scope.ewm_update_param[key])
        }
    
    $scope.postFile(formdata,'/api/app/qrcode/upload').then(function(res) {
        if(res.msg=="成功" && res.content.url) {
            $scope.ewm_url = res.content.url+"&_=" + Date.now();//加时间戳，解决缓存问题
        }
    })

其中input的accept等属性请参照：http://www.haorooms.com/post/input_file_leixing