android下实现最基本的拍照程序源代码，注释详细

package com.demo.android.IsiCamera; import java.io.ByteArrayInputStream; import java.io.FileOutputStream; import android.app.Activity; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.hardware.Camera; import android.net.Uri; import android.os.Bundle; import android.provider.MediaStore; import android.util.Log; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.widget.Button; import android.widget.FrameLayout; import android.widget.Toast; /*classname:IsiCamera1Activity *modifier:public *func:main stream **/ public class IsiCamera1Activity extends Activity { /** Called when the activity is first created. */ final private static String STILL_IMAGE_FILE = "capture.jpg"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); //实例化自己写的CameraSurfaceView对象cameraView final CameraSurfaceView cameraView = new CameraSurfaceView(getApplicationContext()); FrameLayout frame = (FrameLayout) findViewById(R.id.frameLayout1);//??what's frame? frame.addView(cameraView); //Button shared = (Button) findViewById(R.id.shared); //按键触发事件 //Button capture Button capture = (Button) findViewById(R.id.capture); capture.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { cameraView.capture(new Camera.PictureCallback() { public void onPictureTaken(byte[] data, Camera camera) { Log.v("Still", "Image data received from camera"); FileOutputStream fos; try { // Fully qualified path name. In this case, we // use the Files subdir String pathForAppFiles = getFilesDir().getAbsolutePath(); pathForAppFiles = pathForAppFiles + "/" + STILL_IMAGE_FILE; Log.d("Still image filename:", pathForAppFiles); fos = openFileOutput(STILL_IMAGE_FILE, MODE_WORLD_READABLE); fos.write(data); fos.close(); } catch (Exception e) { Log.e("Still", "Error writing file", e); } } }); } }); } //内部class /*classname:CameraSurfaceView * modifier:??can't be private?why? *func:1.向该类中加入一个方法用于捕捉图像（SurfaceHolder实现？？） *2.设置触发机制 *3.定义SurfaceHolder.Callback接口 */ private class CameraSurfaceView extends SurfaceView implements SurfaceHolder.Callback { private SurfaceHolder mSurfaceHolder; private Camera camera = null; //该类的构造函数 public CameraSurfaceView(Context context) { super(context); //初始化SurfaceHolder this.mSurfaceHolder = this.getHolder();//mSurfaceView.getHolder()? how does it know? this.mSurfaceHolder.addCallback(this); this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//设置SurfaceHolder类型 } //implement SurfaceHolder.Callback @Override//necessary? public void surfaceCreated(SurfaceHolder holder) { try { this.camera = Camera.open(); camera.setPreviewDisplay(this.mSurfaceHolder);//unhandled exception type IOExceprion } catch(Exception e) { Log.e("Camera","Failed to set Camera Preview Display",e); } } public void surfaceChanged(SurfaceHolder holder,int format,int width,int height) { Camera.Parameters params = camera.getParameters(); params.setPreviewSize(width,height); camera.setParameters(params); camera.startPreview(); //setPreviewSize后预览将会启动，这时屏幕上将显示摄像头预览画面 } public void surfaceDestroyed(SurfaceHolder holder) { camera.stopPreview(); camera = null; } public boolean capture(Camera.PictureCallback jpegHandler) { if (camera != null) { camera.takePicture(null,null,jpegHandler); return true; } else { return false; } } }//private class }//public class