整体逻辑：service提供FileReader函数，directive提供点击事件的绑定和监听，controller用来修改html上的ng-src属性值
1.HTML
<input type="file" file-model="myFile">/*AngularJS定义的file-Model属性用于对文件进行操作*/
<img alt="配图预览" ng-src="{{imageSrc}}">/*这里用来放置上传的图片进行预览，ng-src是AngularJS定义替代<img>标签的src属性，其值将在后台逻辑获得*/2.AngularJS
1)Controller
.controller('AddarticleCtrl', function ($scope,fileReader) {/*Controller是实际操作html元素的部分*/
$scope.getFile= function () {
fileReader.readAsDataUrl($scope.myFile,$scope)/*注意这里$scope.myFile，要看实际情况，调试发现这里用该调用入参数的myFile属性*/
.then(function (result) {
$scope.imageSrc=result;
});
};
});2）Directive
.directive('fileModel', function ($parse) {/*$parse是AngularJS的内置directive*/
return {
restrict: 'A',/*限制该directive的声明方式 为Attribute*/
link: function (scope, element, attrs) {
var model=$parse(attrs.fileModel);
var modelSetter=model.assign;
element.bind('change',function (event) {/*页面加载时执行*/
scope.$apply(function () {/*当用户点击html上的input标签，选中需要上传的图片 然后点击确定后执行*/
modelSetter(scope,element[0].files[0]);
});
scope.getFile();
});
}
};
});3)Service
.service('fileReader', function ($q) {
// AngularJS will instantiate a singleton by calling "new" on this function
var onLoad=function (reader,deferred,scope) {
return function () {
scope.$apply(function () {
deferred.resolve(reader.result);
});
};
};
var onError=function (reader,deferred,scope) {
return function () {
scope.$apply(function () {
deferred.reject(reader.result);
});
};
};
var getReader=function (deferred,scope) {
var reader=new FileReader();
reader.onload=onLoad(reader,deferred,scope);
reader.onerror=onError(reader,deferred,scope);
return reader;
}
var readAsDataURL=function (file,scope) {/*上传图片的主函数*/
var deferred=$q.defer();
var reader=getReader(deferred,scope);
reader.readAsDataURL(file);
return deferred.promise;
};
return{
readAsDataUrl:readAsDataURL
};
});