详解Angular.js的$q.defer()服务异步处理

function getBase64(img){//传入图片路径，返回base64
   function getBase64Image(img,width,height) {
    var canvas = document.createElement("canvas");
    canvas.width = width ? width : img.width;
    canvas.height = height ? height : img.height;

    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
    var dataURL = canvas.toDataURL();
    return dataURL;
   }
   var image = new Image();
   image.crossOrigin = '';
   image.src = img;

   var base64='';
   if(img){
    image.onload =function (){
     base64=getBase64Image(image);
     console.log(base64);//位置一
    }
    console.log(base64);//位置二
   }
  }

function getBase64(img){//传入图片路径，返回base64
    function getBase64Image(img,width,height) {
     var canvas = document.createElement("canvas");
     canvas.width = width ? width : img.width;
     canvas.height = height ? height : img.height;
     var ctx = canvas.getContext("2d");
     ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
     var dataURL = canvas.toDataURL();
     return dataURL;
    }
    var image = new Image();
    image.crossOrigin = '';
    image.src = img;

    var deferred=$q.defer();
    if(img){
     image.onload =function (){
     deferred.resolve(getBase64Image(image));
     }
     return deferred.promise;
    }
    }

getBase64('https://img.alicdn.com/bao/uploaded/TB1qimQIpXXXXXbXFXXSutbFXXX.jpg')
    .then(function(base64){
     var binaryblob = function (s, type) {//blob对象
      var byteString = atob(s);
      var array = [];
      for (var i = 0; i < byteString.length; i++) {
       array.push(byteString.charCodeAt(i));
      }
      return new Blob([new Int8Array(array)], {type: type});
     };
     var binaryPictureBlob = function (dataUrl, filterHead) {//上传base64去头
      var s = filterHead ? dataUrl.replace(/^data:image\/(png|jpeg|pjpeg|bmp|gif|x-png);base64,/, "") : dataUrl;
      return binaryblob(s, "image/jpeg");
     };
     var pic=binaryPictureBlob(base64,true);//blob对象
     //然后调接口将blob对象上传
    });

var defer1 = $q.defer();

  function fun() {
   var deferred = $q.defer();
   $timeout(function () {
    deferred.notify("notify");
    if (iWantResolve) {
     deferred.resolve("resolved");
    } else {
     deferred.reject("reject");
    }
   }, 500);
   return deferred.promise;
  }

  $q.when(fun())
    .then(function(success){
     console.log("success");
     console.log(success);
    },function(err){
     console.log("error");
     console.log(err);
    },function(notify){
     console.log("notify");
     console.log(notify);
    })
    .catch(function(reson){
     console.log("catch");
     console.log(reson);
    })
    .finally(function(final){
     console.log('finally');
     console.log(final);
    });

var deferred=$q.defer();

 deferred.resolve(success)

 deferred.reject(reason) 

deferred.notify("notify");

 $q.when(fun())
    .then(function(success){
     console.log("success");
     console.log(success);
    },function(err){
     console.log("error");
     console.log(err);
    },function(notify){
     console.log("notify");
     console.log(notify);
    })
    .catch(function(reson){
     console.log("catch");
     console.log(reson);
    })
    .finally(function(final){
     console.log('finally');
     console.log(final);
    });

fun().then(successCallback, errorCallback, notifyCallback);

　　deferred.resolve(success)的success对应successCallback(success)的success。

var iWantResolve = true;//没有实际意思，测试运行resolve或reject

  function promise1() {
   return $q(function (resolve, reject) {
    $timeout(function () {
     if (iWantResolve) {
      resolve("promise1 resolved");
     } else {
      reject("promise1 reject");
     }
    }, 1000)
   })
  }
  promise1()
    .then(function (s1) {//success callback
     console.log(s1);
    })
    .catch(function (err1) {//error callback
     console.log(err1);
    });

  function promise2() {
   var deferred = $q.defer();
   $timeout(function () {
    deferred.notify("promise2 notify");
    if (iWantResolve) {
     deferred.resolve("promise2 resolved");
    } else {
     deferred.reject("promise2 reject");
    }
   }, 500);
   return deferred.promise;
  }

  promise2()
    .then(function (s2) {
     console.log(s2);
    }, function (err2) {
     console.log(err2);
    });

  $q.all([promise1(), promise2()])
    .then(function (dataArr) {
     //promise都成功执行后的回调函数
     console.log("$q.all: ", dataArr);
    }, function (err) {
     console.log("$q.all: ", err)
    });

defer=$.Deferred();
defer.promise();

var deferred=$q.defer();
deferred.promise;