Android Camera - 从服务在后台运行

Question

我一直在尝试在服务后台运行相机。我已经按照How to use Camera to take picture in a background Service on Android?中显示的方法进行操作, Taking picture from camera without preview .这是我做的

实验控制.java

package com.example.test2;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

public class ExperimentControl extends Service 
{
     VideoRecorder vRecorder;   

     public ExperimentControl() 
     {
         Log.i("EXPERIMENT","ExperimentControl started!!!");
     }

     @Override
     public IBinder onBind(Intent intent) 
     {
         return null;
     }

     public int onStartCommand(Intent intent, int flags, int startId) 
     {

        vRecorder = new VideoRecorder();
        vRecorder.startRecording(getApplicationContext());

        return START_STICKY;
     }

     public void onDestroy()
     {
        vRecorder=null;
     }

}

VideoRecorder.java

package com.example.test2;

import java.io.IOException;
import android.content.Context;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class VideoRecorder implements SurfaceHolder.Callback 
{
    String videofolder = android.os.Environment.getExternalStorageDirectory()+"/Record/";
    private final String VIDEO_PATH_NAME = videofolder+"test.mp4";
    private MediaRecorder mMediaRecorder;
    private Camera mCamera;
    private SurfaceView mSurfaceView;
    private SurfaceHolder mHolder;
    private boolean mInitSuccesful;

    void startRecording(Context context)
    {
        Log.v("Surya2","here");
        mSurfaceView = new SurfaceView(context);
        mHolder = mSurfaceView.getHolder();
        mHolder.addCallback(this);
        mMediaRecorder.start();
        try 
        {
            Thread.sleep(10 * 1000);
        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }
        //finish();
        Log.v("Surya4","here");
    }

    private void initRecorder(Surface surface) throws IOException 
    {

        if(mCamera == null) 
        {
            mCamera = Camera.open();
            mCamera.unlock();
        }

        if(mMediaRecorder == null) 
            mMediaRecorder = new MediaRecorder();

        mMediaRecorder.setPreviewDisplay(surface);
        mMediaRecorder.setCamera(mCamera);
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
        mMediaRecorder.setVideoEncodingBitRate(512 * 1000);
        mMediaRecorder.setVideoFrameRate(30);
        mMediaRecorder.setVideoSize(640, 480);
        mMediaRecorder.setOutputFile(VIDEO_PATH_NAME);

        try 
        {
            mMediaRecorder.prepare();
        } 
        catch (IllegalStateException e)
        {
            e.printStackTrace();
        }

        mInitSuccesful = true;
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) 
    {
        try 
        {
            Log.v("Surya3","here");

            if(!mInitSuccesful)
                initRecorder(mHolder.getSurface());
        } 
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder)
    {
        shutdown();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    private void shutdown() 
    {
        // Release MediaRecorder and especially the Camera as it's a shared
        // object that can be used by other applications
        mMediaRecorder.stop();
        mMediaRecorder.reset();
        mMediaRecorder.release();
        mCamera.release();

        // once the objects have been released they can't be reused
        mMediaRecorder = null;
        mCamera = null;
    }
}

list .xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.test2"
    android:versionCode="1"
     android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="17" />

<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-feature android:name="android.hardware.camera.autofocus" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <service android:name=".ExperimentControl" />
</application>

</manifest>

这种方式正确吗？我面临的主要问题是这没有显示任何错误，也没有日志输出。所以我无法确定导致问题的原因，但没有录制视频。有人可以纠正我吗？

提前致谢

Answer 1

尝试使用Service context调用startrecording

vRecorder.startRecording(this);

您应该避免使用 ApplicationContext 创建 View 。当我尝试基于 ApplicationContext 创建 AlertDialog 时，我遇到了类似的问题。没有显示错误，但现在显示了对话框。

希望对您有所帮助!