[feature] 补充通过服务端中转到 CDN 的文件存储方式，兼容海外节点。

Author: wangxiao

lib/file.js

@@ -50,6 +50,13 @@ module.exports = function(AV) {
     return chunks.join("");
   };
 
+  var dataURLToBase64 = function(base64) {
+    if (base64.split(',')[0] && base64.split(',')[0].indexOf('base64') >= 0) {
+      base64 = base64.split(',')[1];
+    }
+    return base64;
+  };
+
   // A list of file extensions to mime types as found here:
   // http://stackoverflow.com/questions/58510/using-net-how-can-you-find-the-
   //     mime-type-of-a-file-based-on-the-file-signature
@@ -317,6 +324,10 @@ module.exports = function(AV) {
    */
   AV.File = function(name, data, type) {
     this._name = name;
+
+    // 用来存储转换后要上传的 base64 String
+    this._base64 = '';
+
     var currentUser;
     try {
       currentUser = AV.User.current();
@@ -337,19 +348,22 @@ module.exports = function(AV) {
     this._guessedType = guessedType;
 
     if (_.isArray(data)) {
-      this._source = AV.Promise.as(encodeBase64(data), guessedType);
+      this._base64 = encodeBase64(data);
+      this._source = AV.Promise.as(this._base64, guessedType);
       this._metaData.size = data.length;
     } else if (data && data.base64) {
       var parseBase64 = require('./browserify-wrapper/parse-base64');
       var dataBase64 = parseBase64(data.base64, guessedType);
+      this._base64 = dataURLToBase64(data.base64);
       this._source = AV.Promise.as(dataBase64, guessedType);
     } else if (data && data.blob) {
       this._source = AV.Promise.as(data.blob, guessedType);
     } else if (typeof(File) !== "undefined" && data instanceof File) {
       this._source = AV.Promise.as(data, guessedType);
     } else if(AV._isNode && global.Buffer.isBuffer(data)) {
       // use global.Buffer to prevent browserify pack Buffer module
-      this._source = AV.Promise.as(data.toString('base64'), guessedType);
+      this._base64 = data.toString('base64');
+      this._source = AV.Promise.as(this._base64, guessedType);
       this._metaData.size = data.length;
     } else if (_.isString(data)) {
       throw "Creating a AV.File from a String is not yet supported.";
@@ -567,10 +581,12 @@ module.exports = function(AV) {
       }
       var self = this;
       if (!self._previousSave) {
-        if(self._source) {
+        // 如果是国内节点
+        if(self._source && AV.serverURL === AV._config.cnApiUrl) {
+          // 通过国内 CDN 服务商上传
           var upload = require('./browserify-wrapper/upload');
           upload(self, AV, saveOptions);
-        } else if(self._url && self._metaData['__source'] == 'external') {
+        } else if (self._url && self._metaData['__source'] == 'external') {
           //external link file.
           var data = {
             name: self._name,
@@ -579,7 +595,7 @@ module.exports = function(AV) {
             mime_type: self._guessedType,
             url: self._url
           };
-          self._previousSave = AV._request("files", self._name, null, 'POST', data).then(function(response) {
+          self._previousSave = AV._request('files', self._name, null, 'POST', data).then(function(response) {
             self._name = response.name;
             self._url = response.url;
             self.id = response.objectId;
@@ -588,6 +604,34 @@ module.exports = function(AV) {
             }
             return self;
           });
+        } else if (AV.serverURL !== AV._config.cnApiUrl) {
+          // 海外节点，通过 LeanCloud 服务器中转
+          self._previousSave = self._source.then(function(file, type) {
+            var data = {
+              base64: '',
+              _ContentType: type,
+              ACL: self._acl,
+              mime_type: type,
+              metaData: self._metaData,
+            };
+            // 判断是否数据已经是 base64
+            if (self._base64) {
+              data.base64 = self._base64;
+              return AV._request('files', self._name, null, 'POST', data);
+            } else {
+              return readAsync(file).then(function(base64) {
+                data.base64 = base64;
+                return AV._request('files', self._name, null, 'POST', data);
+              });
+            }
+          }).then(function(response) {
+            self._name = response.name;
+            self._url = response.url;
+            self.id = response.objectId;
+            if(response.size)
+              self._metaData.size = response.size;
+            return self;
+          });
         }
       }
       return self._previousSave._thenRunCallbacks(options);