android前后摄像头切换demo，startview后的页面上有切换、拍照两个按钮，拍照后照片未保存，需要保存的请看下方注释，实现了拍照、聚焦功能，以下是CameraPreview.java源码：

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package com.myselftest;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.util.ArrayList;

import java.util.List;

import android.content.Context;

import android.hardware.Camera;

import android.hardware.Camera.Size;

import android.os.Bundle;

import android.util.Log;

import android.view.Display;

import android.view.KeyEvent;

import android.view.Surface;

import android.view.SurfaceHolder;

import android.view.View;

import android.view.Window;

import android.view.WindowManager;

import android.widget.TextView;

import android.widget.Toast;

import android.os.Handler;

import android.os.Message;

import android.widget.RelativeLayout;

import android.view.MotionEvent;

import android.app.Activity;

import android.view.View.OnClickListener;

import android.hardware.Camera.CameraInfo;

import android.os.SystemProperties;

import android.view.View.OnTouchListener;

import android.graphics.Rect;

import android.hardware.Camera.PictureCallback;

public class CameraPreview extends Activity implements OnClickListener, SurfaceHolder.Callback {

   private static final String TAG = "CameraPreview";

  private Camera mCamera;

  private Camera.Parameters mCameraParam;

  private int mPrvW = 800;

  private int mPrvH = 600;

  private final AutoFocusCallback mAutoFocusCallback = new AutoFocusCallback();

  private long mFocusCallbackTime;

  private FocusIndicatorView mFocusIndicatorView;

  private static final int WIDTH_DP = 80;

  private static final int HEIGTH_DP = 80;

  private boolean focusing = false;

  private boolean state;

  private TextView btn_position = null;

  private TextView btn_capture = null;

  private SurfaceHolder holder = null;

  private VideoPreview mVideoPreview;

  private int cameraPosition = 1; //1,camera_back 0,camera_front

  private int cameraId;

  private  RelativeLayout mRelativeLayout;

  CameraInfo ci = null;

  public static int dip2px(Context context, float dpValue) {

    final float scale = context.getResources().getDisplayMetrics().density;

    return (int) (dpValue * scale + 0.5f);

  }

  @Override

  protected void onCreate(Bundle savedInstanceState) {

    // TODO Auto-generated method stub

    super.onCreate(savedInstanceState);

    setContentView(R.layout.camera_preview);

    Window win = getWindow();

    win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

    win.addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

    btn_position  = (TextView) findViewById(R.id.btn_position);

    btn_capture = (TextView) findViewById(R.id.btn_capture);

    mPrvW = this.getWindow().getWindowManager().getDefaultDisplay().getWidth();

    mPrvH = mPrvW*4/3;

    mFocusIndicatorView = new FocusIndicatorView(this);

    int width_px = dip2px(this, WIDTH_DP);

    int heigth_px = dip2px(this, HEIGTH_DP);

    RelativeLayout.LayoutParams mLayoutParams = new         RelativeLayout.LayoutParams(width_px, heigth_px);

    int[] rules = mLayoutParams.getRules();

    rules[RelativeLayout.CENTER_IN_PARENT] = 1;

    mRelativeLayout = (RelativeLayout) findViewById(R.id.main_layout);

    mRelativeLayout.addView(mFocusIndicatorView, mLayoutParams);

    mRelativeLayout.setOnTouchListener(onTouchListener);

    mVideoPreview = (VideoPreview) findViewById(R.id.camera_preview);

    btn_position.setOnClickListener(this);

    btn_capture.setOnClickListener(this);

  }

  @Override

public void onClick(View v){

if(v.equals(btn_position)){

camera_position();

}else if(v.equals(btn_capture)){

rawCapture();

}

}

  @Override

  protected void onResume() {

    super.onResume();

    mVideoPreview.setAspectRatio(mPrvW, mPrvH);

    holder = mVideoPreview.getHolder();

    holder.addCallback(this);

    holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

  }

  public boolean onTouchEvent(MotionEvent event) {

    if(focusing == false) {

      focusing = true;

      mFocusIndicatorView.showStart();

      mCamera.autoFocus(mAutoFocusCallback);

    }

    return true;

  }

  public class FocusIndicatorView extends View {

    public FocusIndicatorView(Context context) {

      super(context);

    }

  private void setDrawable(int resid) {

    setBackgroundDrawable(getResources().getDrawable(resid));

  }

  public void showStart() {

    setDrawable(R.drawable.ic_focus_focusing);

  }

  public void showSuccess() {

    setDrawable(R.drawable.ic_focus_focused);

  }

  public void showFail() {

    setDrawable(R.drawable.ic_focus_failed);

  }

  public void clear() {

    setBackgroundDrawable(null);

  }

  }

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

    Log.i(TAG, "surfaceChanged width is : " + width+" height is"+height+" ci.orientation="+ci.orientation);

    startPreview(ci.orientation);

  }

  public void surfaceCreated(SurfaceHolder holder) {

    // TODO Auto-generated method stub

  ci = new CameraInfo();

  Camera.getCameraInfo(0, ci);

    openCamera(0);

    cameraId = 0;

    try {

      mCamera.setPreviewDisplay(holder);

    } catch (IOException exception) {

      closeCamera();

      Log.i(TAG, "surfaceCreated closeCamera ");

    }

  }

  private void openCamera(int cmaId) {

    if (mCamera == null) {

      mCamera = Camera.open(cmaId);

      cameraId = cmaId;

      Log.i(TAG, "Enter openCamera to init the mCamera.");

      if (null == mCamera) {

        Log.i(TAG, "init the mCamera is null.");

      }

    }

  }

  private void closeCamera() {

    if (null != mCamera) {

      mCamera.release();

      mCamera = null;

    }

  }

  public void surfaceDestroyed(SurfaceHolder holder) {

    // TODO Auto-generated method stub

    stopPreview();

    closeCamera();

    Log.i(TAG, "surfaceDestroyed closeCamera ");

  }

  private void stopPreview() {

    if (null != mCamera) {

      mCamera.stopPreview();

    }

  }

  private Handler mHandler = new Handler() {

  @Override

    public void handleMessage(Message msg) {

      // TODO Auto-generated method stub

      super.handleMessage(msg);

      if (0 == msg.what) {

        mFocusIndicatorView.clear();

      }

    }

  };

  private void startPreview(int orientation) {//orientation：当前所选摄像头的偏转角度

  if (null != mCamera) {

  mCameraParam = mCamera.getParameters();

  }else{

  return;

  }

    Size size = mCameraParam.getPictureSize();

    List sizes = mCameraParam.getSupportedPreviewSizes();

    Size optimalSize = null;

    if (size != null && size.height != 0) {

      optimalSize = getOptimalPreviewSize(sizes, (double) mPrvH / mPrvW);

    }

    if (optimalSize != null) {

      mCameraParam.setPreviewSize(optimalSize.width, optimalSize.height);

    } else {

      mCameraParam.setPreviewSize(mPrvW, mPrvH);

    }

    mCameraParam.set("fps-mode", 0); // Frame rate is normal

    mCameraParam.set("cam-mode", 0); // Cam mode is preview

    if (cameraPosition == 1) {

      mCameraParam.setFocusMode(mCameraParam.FOCUS_MODE_CONTINUOUS_PICTURE);

      mCameraParam.setFlashMode(Camera.Parameters.FLASH_MODE_ON);

    }

    mCamera.setDisplayOrientation(orientation);

    mCamera.setParameters(mCameraParam);

    mCamera.startPreview();

    mCamera.autoFocus(mAutoFocusCallback);

  }

  private Size getOptimalPreviewSize(List sizes, double targetRatio) {

    final double ASPECT_TOLERANCE = 0.05;

    if (sizes == null) {

      return null;

    }

    Size optimalSize = null;

    double minDiff = Double.MAX_VALUE;

    Display display = getWindowManager().getDefaultDisplay();

    int targetHeight = Math.min(display.getHeight(), display.getWidth());

    if (targetHeight <= 0) {

      WindowManager windowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);

      targetHeight = windowManager.getDefaultDisplay().getHeight();

    }

    Log.d(TAG, "getOptimalPreviewSize() sizes.size = " + sizes.size());

    int i = 1;

    for (Size size : sizes) {

      double ratio = (double) size.width / size.height;

      i++;

      if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) {

        continue;

      }

      if (Math.abs(size.height - targetHeight) < minDiff) {

        optimalSize = size;

        minDiff = Math.abs(size.height - targetHeight);

      }

    }

    if (optimalSize == null) {

      Log.d(TAG, "No preview size match the aspect ratio");

      minDiff = Double.MAX_VALUE;

      for (Size size : sizes) {

        if (Math.abs(size.height - targetHeight) < minDiff) {

          optimalSize = size;

          minDiff = Math.abs(size.height - targetHeight);

        }

      }

    } else {

      Log.d(TAG, String.format("Optimal preview size is %sx%s", optimalSize.width, optimalSize.height));

    }

    return optimalSize;

  }

  @Override

  public boolean onKeyDown(int keyCode, KeyEvent event) {

    switch (keyCode) {

    case KeyEvent.KEYCODE_DPAD_CENTER:

      return true;

    case KeyEvent.KEYCODE_SEARCH:

      return true;

    case KeyEvent.KEYCODE_FOCUS:

      return true;

    case KeyEvent.KEYCODE_BACK:

      break;

    }

    return super.onKeyDown(keyCode, event);

  }

  private void camera_position(){

  CameraInfo cameraInfo = new CameraInfo();

  int cameraCount = Camera.getNumberOfCameras();

  for(int i = 0; i

  Camera.getCameraInfo(i, cameraInfo);

  Log.d(TAG, "cameraOrientation-"+i+":"+cameraInfo.orientation);

if(cameraPosition == 0){

  if(cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_BACK){

  stopPreview();

  closeCamera();

  openCamera(i);

  cameraPosition = 1;

  if (null != mCamera) {

  try {

          mCamera.setPreviewDisplay(holder);

        } catch (IOException ex) {

          closeCamera();

          Log.i(TAG, "camera_position closeCamera "+i);

          ex.printStackTrace();

        }

  startPreview(cameraInfo.orientation);

  }

  break;

  }

  }else{

  if(cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT){

  stopPreview();

  closeCamera();

  openCamera(i);

  cameraPosition = 0;

  if (null != mCamera) {

  try {

          mCamera.setPreviewDisplay(holder);

        } catch (IOException ex) {

          closeCamera();

          Log.i(TAG, "camera_position closeCamera "+i);

          ex.printStackTrace();

        }

  startPreview(90);

  }

  break;

  }

  }

  }

  }

  private void rawCapture() {

    if(mCamera != null){

      try {

      mCamera.startPreview();

      mCamera.autoFocus(mAutoFocusCallback);

      mCamera.takePicture(null, null,  new JpegPictureCallback());

      Toast.makeText(this, getString(R.string.cma_capture_success), Toast.LENGTH_LONG).show();

      mCamera.stopPreview();

      mCamera.setPreviewDisplay(holder);

      mCamera.startPreview();

    }catch(Exception ex){

    closeCamera();

    ex.printStackTrace();

    }

Log.i(TAG, "rawCapture function end");

    }

  }

  private final class AutoFocusCallback implements android.hardware.Camera.AutoFocusCallback {

    public void onAutoFocus(boolean focused, android.hardware.Camera camera) {

      mFocusCallbackTime = System.currentTimeMillis();

      Log.i(TAG, "mFocusCallbackTime is " + mFocusCallbackTime);

      if(focused && !state) {

        mFocusIndicatorView.showSuccess();

        mHandler.sendEmptyMessageDelayed(0, 1500);

      } else if(!focused){

        mHandler.removeMessages(0);

        mFocusIndicatorView.showFail();

      }

      focusing =  false;

      state = focused;

    }

  }

  private final class JpegPictureCallback implements PictureCallback {

    public void onPictureTaken(byte[] jpegData, android.hardware.Camera camera) {

      Log.d(TAG, "mJpegPictureCallbackTime = " + System.currentTimeMillis());

      if (jpegData != null) {

        storeImage(jpegData);

      }

    }

  }

  private void storeImage(byte[] jpegData) {//本例未保存所拍照片，如需要保存，请取消下方的注释

    String name = "factorymode_test.jpg";

//     File fHandle = new File(name);

//     try {

//       OutputStream bos = new FileOutputStream(fHandle);

//       bos.write(jpegData);

//       bos.close();

//       long storeImageTime = System.currentTimeMillis();

//       Log.d(TAG, "storeImageTime = " + storeImageTime);

//     } catch (Exception ex) {

//       fHandle.delete();

//     }

  }

  OnTouchListener onTouchListener = new OnTouchListener(){

  @Override

  public boolean onTouch(View v, MotionEvent event){

  mFocusIndicatorView.setX(event.getX());

mFocusIndicatorView.setY(event.getY());

  if(event.getAction() == MotionEvent.ACTION_DOWN){

  mFocusIndicatorView.showSuccess();

  }else if(event.getAction() == MotionEvent.ACTION_UP){

  mFocusIndicatorView.showFail();

  if(cameraPosition == 1){

  focusOnTouch(event);

  }

  }

  return true;

  }

  };

  private void focusOnTouch(MotionEvent event){

  int [] location = new int[2];

  mRelativeLayout.getLocationOnScreen(location);

  Rect focusRect = calculateTapArea(mVideoPreview.getWidth(), mVideoPreview.getHeight(), 1f, event.getRawX(),

  event.getRawY(), location[0], location[0] + mRelativeLayout.getWidth(), location[1], location[1] + mRelativeLayout.getHeight());

  Rect meteringRect = calculateTapArea(mVideoPreview.getWidth(), mVideoPreview.getHeight(), 1.5f, event.getRawX(),

event.getRawY(), location[0], location[0] + mRelativeLayout.getWidth(), location[1], location[1] + mRelativeLayout.getHeight());

  mCameraParam.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);

  if(mCameraParam.getMaxNumFocusAreas() > 0){

  List focusAreas = new ArrayList();

  focusAreas.add(new Camera.Area(focusRect,  1000));

  mCameraParam.setFocusAreas(focusAreas);

  }

  if(mCameraParam.getMaxNumMeteringAreas() > 0){

  List meteringAreas = new ArrayList();

  meteringAreas.add(new Camera.Area(meteringRect,  1000));

  mCameraParam.setMeteringAreas(meteringAreas);

  }

  if(mCamera != null){

  mCamera.setParameters(mCameraParam);

  }

  mCamera.autoFocus(mAutoFocusCallback);

  }

  private Rect calculateTapArea(int focusWidth, int focusHeight, float areaMultiple, float x, float y, int previewLeft, int previewRight, int preViewTop, int preViewBottom){

  int areaWidth = (int)(focusWidth * areaMultiple);

  int areaHeight = (int)(focusHeight * areaMultiple);

  int centerX = (previewLeft + previewRight) / 2;

  int centerY = (preViewTop + preViewBottom) / 2;

  double unitx = (((double)previewRight - (double)previewLeft)) /2000;

  double unity = (((double)preViewBottom - (double)preViewTop)) /2000;

  int left = clamp((int)(((x - areaWidth / 2) - centerX) / unitx),  -1000, 1000);

  int top = clamp((int)(((y - areaHeight / 2) - centerY) / unity),  -1000, 1000);

  int right = clamp((int)(left + areaWidth / unitx),  -1000, 1000);

  int bottom = clamp((int)(top + areaHeight / unity),  -1000, 1000);

  return new Rect(left, top, right, bottom);

  }

  private int clamp(int x, int min, int max){

  if(x > max){

  return max;

  }

  if(x < min){

  return min;

  }

  return x;

  }

}

camera_preview.xml布局文件：

 xmlns:android="http://schemas.android.com/apk/res/android"

 android:layout_width="fill_parent"

 android:layout_height="fill_parent"

 android:id="@+id/main_layout"

 android:orientation="vertical">

 

 android:id="@+id/camera_preview"

 android:layout_width="fill_parent"

 android:layout_height="fill_parent"

 android:layout_centerInParent="true"/>

 

   android:id="@+id/btn_capture"

   android:layout_width="wrap_content"

   android:layout_height="wrap_content"

   android:layout_alignParentBottom="true"

   android:layout_alignParentRight="true"

   android:layout_marginRight="33dp"

   android:gravity="center"

   android:text="@string/cma_capture" />

 

   android:id="@+id/btn_position"

   android:layout_width="wrap_content"

   android:layout_height="wrap_content"

   android:layout_alignParentBottom="true"

   android:layout_alignParentLeft="true"

   android:layout_marginLeft="48dp"

   android:gravity="center"

   android:text="@string/cma_position" />

以上代码在android6.0上测试通过。

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本文名称：android前后摄像头切换-创新互联
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