<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >
 <LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical"
  android:layout_weight="2">
  <SurfaceView
   android:id="@+id/surfaceView"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent" />
 </LinearLayout>
 <LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:orientation="horizontal"
  android:layout_weight="1"
  android:background="@android:color/white"
  android:layout_gravity="center">
  <ImageButton android:layout_width="fill_parent"
   android:layout_height="80dip"
   android:id="@+id/btnTakePicture"
   android:layout_gravity="center"
   android:textSize="30dip"
   android:layout_weight="1"
   android:src="@drawable/btn_take_pic"/>
  <ImageButton android:layout_width="fill_parent"
   android:layout_height="80dip"
   android:id="@+id/btnAutoFocus"
   android:layout_gravity="center"
   android:textSize="30dip"
   android:layout_weight="1"
   android:src="@drawable/btn_auto_focus"/>
 </LinearLayout>
</LinearLayout>

package cn.itcast.takepicture;
import java.io.File;
import java.io.FileOutputStream;
import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.PixelFormat;
import android.graphics.Bitmap.CompressFormat;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.SurfaceHolder.Callback;
import android.widget.ImageButton;
public class MainActivity extends Activity {
 private ImageButton btnTakePicture = null;
 private ImageButton btnAutoFocus = null;
 private Camera camera = null;
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  // 设置窗口标题
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  // 横屏
  setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
  // 全屏显示
  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
  WindowManager.LayoutParams.FLAG_FULLSCREEN);
  // 当此窗口为用户可见时，保持设备常开，并保持亮度不变。
  getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
  setContentView(R.layout.main);
  SurfaceView surfaceView = (SurfaceView) this
    .findViewById(R.id.surfaceView);
  surfaceView.getHolder()
    .setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
  surfaceView.getHolder().setFixedSize(320, 240); // 设置分辨率
  surfaceView.getHolder().addCallback(new SurfaceCallback());
  btnTakePicture = (ImageButton) findViewById(R.id.btnTakePicture);
  btnAutoFocus = (ImageButton) findViewById(R.id.btnAutoFocus);
  btnTakePicture.setOnClickListener(onClickListener);
  btnAutoFocus.setOnClickListener(onClickListener);
 }
 private final View.OnClickListener onClickListener = new View.OnClickListener() {
  @Override
  public void onClick(View v) {
   if (v == btnTakePicture) {
    if (camera != null)
     camera.takePicture(null, null, new TakePictureCallback()); // 拍照
   } else if (v == btnAutoFocus) {
    if (camera != null)
     camera.autoFocus(null); // 对焦
   }
  }
 };
 private final class SurfaceCallback implements Callback {
  private boolean preview; // 是否正在预览
  @Override
  public void surfaceChanged(SurfaceHolder holder, int format, int width,
    int height) {
  }
  @Override
  public void surfaceCreated(SurfaceHolder holder) {
   try {
    camera = Camera.open();
    Camera.Parameters parameters = camera.getParameters();
    parameters.setPreviewFrameRate(5); //每秒5帧
    parameters.setPictureFormat(PixelFormat.JPEG);//设置照片的输出格式
    parameters.set("jpeg-quality", 85);//照片质量
    camera.setParameters(parameters);
    camera.setPreviewDisplay(holder);
    camera.startPreview();
    preview = true;
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
  @Override
  public void surfaceDestroyed(SurfaceHolder holder) {
   if (camera != null) {
    if (preview) {
     camera.stopPreview();
     preview = false;
    }
    camera.release();
    camera = null; // 记得释放
   }
  }
 }
 private final class TakePictureCallback implements PictureCallback {
  public void onPictureTaken(byte[] data, Camera camera) {
   Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
   Matrix matrix=new Matrix();
   //设置缩放
   matrix.postScale(0.5f, 0.5f);
   bitmap=Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
   File file = new File(Environment.getExternalStorageDirectory(),
     System.currentTimeMillis() + ".jpg");
   try {
    FileOutputStream outStream = new FileOutputStream(file);
    bitmap.compress(CompressFormat.JPEG, 100, outStream);
    outStream.close();
    camera.startPreview();
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
 }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="cn.itcast.takepicture"
 android:versionCode="1"
 android:versionName="1.0" >
 <application
  android:icon="@drawable/icon"
  android:label="@string/app_name" >
  <activity
   android:label="@string/app_name"
   android:name=".MainActivity" >
   <intent-filter >
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
  </activity>
 </application>
 <uses-sdk android:minSdkVersion="7" />
 <uses-permission android:name="android.permission.CAMERA" />
 <!-- 在SDCard中创建与删除文件权限 -->
 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
 <!-- 往SDCard写入数据权限 -->
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
</manifest>