自定义拍照会用到SurfaceView控件显示照片的预览区域，以下是布局文件：

两个TextView是用来显示提示信息和倒计时的秒数的

相关教程：Android开发从相机或相册获取图片裁剪

Android启动相机拍照并返回图片

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="#266194"
 android:orientation="vertical"
 tools:context=".TestActivity" >
 <SurfaceView
 android:id="@+id/surfaceView"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:layout_centerInParent="true" />
 <LinearLayout
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerInParent="true"
 android:orientation="vertical" >
 <TextView
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:text="请调整位置到此区域"
 android:textColor="#ff0000"
 android:textSize="32sp" />
 <TextView
 android:id="@+id/tv_time"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:paddingTop="10dp"
 android:gravity="center_horizontal"
 android:textColor="#266194"
 android:textSize="32sp" />
 </LinearLayout>
</RelativeLayout> 

接下来是mainActivity中的具体实现以及详细注释：

package com.dhsr.pujiejia.ui;
import java.io.File;
import java.io.FileOutputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
import android.widget.TextView;
import com.example.pujiejiaapp.R;
@SuppressLint({ "NewApi", "SdCardPath" })
public class CameraActivity extends Activity implements Runnable {
 // 预览图片范围
 private SurfaceView surfaceView;
 private TextView tv_time;
 // 倒计时拍摄
 private int cameratime = 4;
 private Camera camera;
 private boolean preview = false;
 // 文件名字
 private String filename;
 // 文件名字的带的时间戳
 private String timeString;
 // 格式化时间
 private SimpleDateFormat dateFormat;
 // 日期对象
 private Date date;
 // 控制线程
 boolean stopThread = false;
 private File file;
 String photo;
 private Handler mHandler = new Handler() {
 public void handleMessage(android.os.Message msg) {
 int what = msg.what;
 switch (what) {
 case 222:
 tv_time.setText("" + cameratime);
 if ("0".equals(tv_time.getText().toString())) {
  tv_time.setText("拍摄成功！");
  takePhoto();
 }
 break;
 }
 };
 };
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 // TODO Auto-generated method stub
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_test);
 CameraActivity.this.setFinishOnTouchOutside(false);
 // 初始化数据
 findView();
 surfaceView.getHolder().addCallback(new SufaceListener());
 /* 下面设置Surface不维护自己的缓冲区，而是等待屏幕的渲染引擎将内容推送到用户面前 */
 surfaceView.getHolder()
 .setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
 surfaceView.getHolder().setFixedSize(200, 200); // 设置分辨率
 }
 @Override
 protected void onStart() {
 // TODO Auto-generated method stub
 super.onStart();
 // 开启线程
 new Thread(this).start();
 }
 private final class SufaceListener implements SurfaceHolder.Callback {
 /**
 * surface改变
 */
 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width,
 int height) {
 }
 /**
 * surface创建
 */
 @Override
 public void surfaceCreated(SurfaceHolder holder) {
 try {
 for (int i = 0; i < Camera.getNumberOfCameras(); i++) {
  CameraInfo info = new CameraInfo();
  Camera.getCameraInfo(i, info);
  // 调用系统的前置摄像头
  if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
  camera = Camera.open(i);
  }
 }
 Camera.Parameters parameters = camera.getParameters();
 /* 每秒从摄像头捕获5帧画面， */
 parameters.setPreviewFrameRate(5);
 /* 设置照片的输出格式:jpg */
 parameters.setPictureFormat(PixelFormat.JPEG);
 /* 照片质量 */
 parameters.set("jpeg-quality", 85);
 WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
 camera.setParameters(parameters);
 camera.setPreviewDisplay(surfaceView.getHolder());// 通过SurfaceView显示取景画面
 camera.startPreview();
 preview = true;
 } catch (Exception e) {
 }
 }
 /**
 * surface销毁
 */
 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
 if (camera != null) {
 if (preview)
  camera.stopPreview();
 camera.release();
 camera = null;
 }
 }
 }
 /**
 * 拍摄照片
 */
 private void takePhoto() {
 // 执行拍照效果
 camera.takePicture(null, null, new Camera.PictureCallback() {
 @Override
 public void onPictureTaken(byte[] data, Camera camera) {
 try {
  Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0,
  data.length);
  timeString = formatDate();
  //保存到data/data目录自定义文件夹下
  filename = "/data/data/com.example.pujiejiaapp/images/"
  + timeString + ".jpg";
  File file = new File(filename);
  boolean createNewFile = file.createNewFile()
  System.out.println("创建文件夹成功没有" + createNewFile);
  System.out.println(file);
  FileOutputStream outStream = new FileOutputStream(file);
  bitmap.compress(Bitmap.CompressFormat.JPEG, 60, outStream);
  outStream.flush();
  outStream.close();
  // 重新浏览
  camera.stopPreview();
  camera.startPreview();
  preview = true;
 } catch (Exception e) {
  e.printStackTrace();
 } finally {
 }
 }
 });
 }
 @Override
 public void run() {
 while (!stopThread) {
 try {
 //按秒数倒计时
 Thread.sleep(1000);
 } catch (InterruptedException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 cameratime--;
 mHandler.sendEmptyMessage(222);
 if (cameratime <= 0) {
 break;
 }
 }
 }
 // 初始化数据
 private void findView() {
 surfaceView = (SurfaceView) this.findViewById(R.id.surfaceView);
 tv_time = (TextView) findViewById(R.id.tv_time);
 }
 // 格式化系统的时间
 public String formatDate() {
 date = new Date(System.currentTimeMillis());
 // 日期格式
 dateFormat = new SimpleDateFormat("'IMG'_yyyyMMddHHmmss");
 return dateFormat.format(date);
 }
 @Override
 protected void onDestroy() {
 // TODO Auto-generated method stub
 // 线程已关闭
 super.onDestroy();
 stopThread = true;
 }
} 

核心代码详解：

1.创建SurfaceView时，surfaceCreated()方法中

for (int i = 0; i < Camera.getNumberOfCameras(); i++) {
  CameraInfo info = new CameraInfo();
  Camera.getCameraInfo(i, info);
  // 调用系统的前置摄像头
  if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
  camera = Camera.open(i);
  }
 }

此部分代码为打开相机时默认打开前置摄像头CameraInfo.CAMERA_FACING_BACK为默认打开后置摄像头，CameraInfo.CAMERA_FACING_FRONT前置摄像头

2.照片拍摄takePhoto()方法中：

Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0,
  data.length);
  timeString = formatDate();
  filename = "/data/data/com.example.pujiejiaapp/images/"
  + timeString + ".jpg";
  photo = timeString + ".jpg";
  File file = new File(filename);
  boolean createNewFile = file.createNewFile();
  FileOutputStream outStream = new FileOutputStream(file);
  bitmap.compress(Bitmap.CompressFormat.JPEG, 60, outStream);

此部分代码为将拍摄到的图片保存为以bitmap格式保存在指定的目录下

3.开子线程用于倒计时拍摄

public void run() {
 while (!stopThread) {
 try {
 Thread.sleep(1000);
 } catch (InterruptedException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 cameratime--;
 mHandler.sendEmptyMessage(222);
 if (cameratime <= 0) {
 break;
 }
 }
 }

希望大家理解核心代码的详细注释，欢迎提供意见，希望能给大家带来帮助，谢谢！