通过hash索引文件, 而不是按顺序

node_modules/file.js

@@ -49,17 +49,30 @@ var File = {
 
       	// return;
       	try {
-			var err = fs.writeFileSync(filePath, new Buffer(data, 'base64'));
+      		var bf = new Buffer(data, 'base64');
+			var err = fs.writeFileSync(filePath, bf);
 			if(err) {
 				return callback(false);
 			}
+
+			// 得到文件的hash
+			var hash = crypto.createHash('md5');
+			hash.setEncoding('hex');
+			hash.write(bf);
+			hash.end();
+			var fileHash = hash.read();
+
 			if(isImage) {
 				me._addImage(Common.objectId(), filePath, function(newImg) {
 					newImg.IsImage = true;
+					newImg.hash = fileHash;
 					callback && callback(newImg);
 				});
 			} else {
-				me._addAttach(filePath, fileTitle, callback)
+				me._addAttach(filePath, fileTitle, function(attach) {
+					attach.hash = fileHash;
+					callback && callback(attach);
+				});
 			}
 
 			/*