Android锁屏出现java.lang.RuntimeException: Camera is being used after Camera.release() was called

        java.lang.RuntimeException: Camera is being used after Camera.release() was called

        在相机开发中，打开相机显示预览，然后按关机键锁屏，出现上述错误，程序崩溃。

        原来代码如下：

@Override    public void surfaceDestroyed(SurfaceHolder arg0) {        // TODO Auto-generated method stub        //super.onDestroy();        if(camera != null) {//            holder.removeCallback(this);//            camera.setPreviewCallback(null);            camera.stopPreview();        }        holder = null;    }

 @Override    protected void onPause() {        super.onPause();        finish();//如果点home键，销毁当前页，返回前一页。    }    @Override    protected void onDestroy() {        super.onDestroy();        if(camera != null) {            camera.release();        }        finish();    }

       之前如果点击home键，再点APP图标进入程序，相机预览界面黑屏，要返回上一页再重新进入当前页相机预览界面才正常显示。后来我想了个偷懒的做法，在onPause方法里添加finish()方法，如果点home键，则销毁当前页，返回前一页。

       现在又出现了一个新问题，如果按关机键锁屏，就会出现上面的错误。想到应该是activity的生命周期问题，就在清单文件里配置了禁止横竖屏切换，还是出现上述错误。然后网上搜解决方法，有的说在surfaceDestroyed()添加holder.removeCallback(this)，有的说添加holder.removeCallback(this)。经测试，无效。后来在onDestroy方法里camera.release()后添加camera = null，问题解决。

       修改后的代码：

@Override    protected void onDestroy() {        super.onDestroy();        if(camera != null) {            camera.release();            camera = null;        }        finish();    }

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