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AngularJS中的promise用法分析

更新時(shí)間：2017年05月19日 08:52:37 作者：timelessmemoryli

這篇文章主要介紹了AngularJS中的promise用法,結(jié)合實(shí)例形式分析了AngularJS異步處理模式promise具體功能、使用方法與相關(guān)注意事項(xiàng),需要的朋友可以參考下

本文實(shí)例講述了AngularJS中的promise用法。分享給大家供大家參考，具體如下：

JavaScript異步回調(diào)有好處也有壞處，回調(diào)函數(shù)大量嵌套十分復(fù)雜．所以javascript中還有另一種異步處理模式叫promises．在AngularJS中的實(shí)現(xiàn)就是$q服務(wù)．

下面是一些小例子．

then,catch,finally

在鏈最后的 catch 為整個(gè)鏈?zhǔn)教幚硖峁┮粋€(gè)異常處理點(diǎn)
在鏈最后的 finally 總是會(huì)被執(zhí)行，不管 promise 被處理或者被拒絕，起清理作用

<!DOCTYPE html>
<html>
  <head>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
    <script src="jQuery.min.js"></script>
    <script src="angular.min.js"></script>
    <script src="bootstrap.min.js"></script>
    <script type="text/javascript">
      var myapp = angular.module('myapp', []);
      myapp.controller('myController', function($scope, $q) {
        $scope.send = function() {
          var deferred = $q.defer();
          var promise = deferred.promise;
          promise
          .then(function() {
            console.log('resolve.....')
          }, function() {
            console.log('reject.....');
          }, function() {
            console.log('notify.....');
          })
          .catch(function() {
            console.log('catch..error..')
          })
          .finally(function() {
            console.log('anywhere will be called..');
          });
          deferred.reject('resolve');
        };
      });
    </script>
    <style type="text/css">
    </style>
  </head>
  <body ng-app="myapp">
    <div ng-controller="myController">
        <button class="btn" ng-click="send()">click</button>
    </div>
  </body>
</html>

then第三個(gè)參數(shù)(表征狀態(tài))的應(yīng)用

<!DOCTYPE html>
<html>
  <head>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
    <script src="jquery.min.js"></script>
    <script src="angular.min.js"></script>
    <script src="bootstrap.min.js"></script>
    <script type="text/javascript">
      var myapp = angular.module('myapp', []);
      myapp.controller('myController', function($scope, dataService) {
        $scope.send = function() {
          dataService.getData()
          .then(function success(data) {
            console.log(data);
          }, function error(error) {
            console.log(error);
          }, function status(process) {
            console.log(process);
          });
        };
      });
      myapp.factory('dataService', function($q, $interval) {
        return {
          getData : function() {
            var deferred = $q.defer();
            var process = 0;
            var interval = $interval(function() {
              process += 10;
              deferred.notify(process);
              //reject之后不再繼續(xù)運(yùn)行
              // if (process == 50) {
              //   deferred.reject(process);
              // }
              if (process >= 100) {
                $interval.cancel(interval);
                deferred.resolve(process);
              }
            }, 1000);
            return deferred.promise;
          }
        };
      });
    </script>
    <style type="text/css">
    </style>
  </head>
  <body ng-app="myapp">
    <div ng-controller="myController">
        <button class="btn" ng-click="send()">click</button>
    </div>
  </body>
</html>

then鏈?zhǔn)?/p>

<!DOCTYPE html>
<html>
  <head>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
    <script src="jquery.min.js"></script>
    <script src="angular.min.js"></script>
    <script src="bootstrap.min.js"></script>
    <script type="text/javascript">
      var myapp = angular.module('myapp', []);
      myapp.controller('myController', function($scope, $q) {
        $scope.send = function() {
          var deferred = $q.defer();
          var promise = deferred.promise;
          promise
          .then(function() {
            console.log('1.....')
          })
          .then(function() {
            console.log('2....');
          });
          deferred.resolve('resolve');
        };
      });
    </script>
    <style type="text/css">
    </style>
  </head>
  <body ng-app="myapp">
    <div ng-controller="myController">
        <button class="btn" ng-click="send()">click</button>
    </div>
  </body>
</html>

then鏈會(huì)把上一個(gè) then 的返回結(jié)果傳遞給調(diào)用鏈的下一個(gè) then (如果沒有就是 undefined).

<!DOCTYPE html>
<html>
  <head>
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
    <script src="jquery.min.js"></script>
    <script src="angular.min.js"></script>
    <script src="bootstrap.min.js"></script>
    <script type="text/javascript">
      var myapp = angular.module('myapp', []);
      myapp.controller('myController', function($scope, $q, $timeout) {
        $scope.send = function() {
          var deferred = $q.defer();
          var promise = deferred.promise;
          deferred.resolve('resolve');
          promise
          .then(function(data) {
            console.log(data);
            var _deferred = $q.defer();
            $timeout(function() {
            _deferred.resolve('resolve_');
            }, 1000);
            return _deferred.promise;
          })
          .then(function(data) {
            console.log(data);
          });
        };
      });
    </script>
    <style type="text/css">
    </style>
  </head>
  <body ng-app="myapp">
    <div ng-controller="myController">
        <button class="btn" ng-click="send()">click</button>
    </div>
  </body>
</html>

如果 then 返回一個(gè) promise 對(duì)象，下一個(gè) then 只會(huì)在這個(gè) promise 被處理結(jié)束的時(shí)候調(diào)用。

更多關(guān)于AngularJS相關(guān)內(nèi)容感興趣的讀者可查看本站專題：《AngularJS指令操作技巧總結(jié)》、《AngularJS入門與進(jìn)階教程》及《AngularJS MVC架構(gòu)總結(jié)》

希望本文所述對(duì)大家AngularJS程序設(shè)計(jì)有所幫助。

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