二维码扫描

代码说明：

 *  Created by Ralf Kistner on 16/10/2009.  *  Copyright 2008 ZXing authors All rights reserved.  *  Modified by Lukasz Warchol on 02/02/2010.  *  * Licensed under the Apache License, Version 2.0 (the "License");  * you may not use this file except in compliance with the License.  * You may obtain a copy of the License at  *  *      http://www.apache.org/licenses/LICENSE-2.0  *  * Unless required by applicable law or agreed to in writing, software  * distributed under the License is distributed on an "AS IS" BASIS,  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  * See the License for the specific language governing permissions and  * limitations under the License.