android.hardware.CameraThe Camera class is used to set image capture settings, start/stop preview, snap pictures, and retrieve frames for encoding for video. This class is a client for the Camera service, which manages the actual camera hardware.To access the device camera, you must declare the android.Manifest.permission.CAMERA permission in your Android Manifest. Also be sure to include the <uses-feature> manifest element to declare camera features used by your application. For example, if you use the camera and auto-focus feature, your Manifest should include the following: <uses-permission android:name="android.permission.CAMERA" /> <uses-feature android:name="android.hardware.camera" /> <uses-feature android:name="android.hardware.camera.autofocus" />To take pictures with this class, use the following steps:Obtain an instance of Camera from open(int).Get existing (default) settings with getParameters().If necessary, modify the returned Camera.Parameters object and call setParameters(Camera.Parameters).If desired, call setDisplayOrientation(int).Important: Pass a fully initialized SurfaceHolder to setPreviewDisplay(SurfaceHolder). Without a surface, the camera will be unable to start the preview.Important: Call startPreview() to start updating the preview surface. Preview must be started before you can take a picture.When you want, call takePicture(Camera.ShutterCallback, Camera.PictureCallback, Camera.PictureCallback, Camera.PictureCallback) to capture a photo. Wait for the callbacks to provide the actual image data.After taking a picture, preview display will have stopped. To take more photos, call startPreview() again first.Call stopPreview() to stop updating the preview surface.Important: Call release() to release the camera for use by other applications. Applications should release the camera immediately in android.app.Activity.onPause() (and re-open() it in android.app.Activity.onResume()).To quickly switch to video recording mode, use these steps:Obtain and initialize a Camera and start preview as described above.Call unlock() to allow the media process to access the camera.Pass the camera to android.media.MediaRecorder.setCamera(Camera). See android.media.MediaRecorder information about video recording.When finished recording, call reconnect() to re-acquire and re-lock the camera.If desired, restart preview and take more photos or videos.Call stopPreview() and release() as described above.This class is not thread-safe, and is meant for use from one event thread. Most long-running operations (preview, focus, photo capture, etc) happen asynchronously and invoke callbacks as necessary. Callbacks will be invoked on the event thread open(int) was called from. This class‘s methods must never be called from multiple threads at once.Caution: Different Android-powered devices may have different hardware specifications, such as megapixel ratings and auto-focus capabilities. In order for your application to be compatible with more devices, you should not make assumptions about the device camera specifications.

我就不翻译了，应该不难懂<uses-feature android:name="android.hardware.camera" />The application uses the device‘s camera. If the device supports multiple cameras, the application uses the camera that facing away from the screen.<uses-feature android:name="android.hardware.camera.autofocus" />Subfeature. The application uses the device camera‘s autofocus capability.<uses-feature android:name="android.hardware.camera.flash" />Subfeature. The application uses the device camera‘s flash.<uses-feature android:name="android.hardware.camera.front" />Subfeature. The application uses a front-facing camera on the device.<uses-feature android:name="android.hardware.camera.any" />The application uses at least one camera facing in any direction, or an external camera device if one is connected. Use this in preference to android.hardware.camera if a back-facing camera is not required.

<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"    tools:context="com.example.demo_camera.MainActivity" >    <Button        android:id="@+id/main_btn"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:layout_centerVertical="true"        android:text="@string/main_btn_open_camera" />    <include        android:id="@+id/camera_layout"        android:layout_width="match_parent"        android:layout_height="match_parent"        layout="@layout/view_camera"        android:visibility="gone" /></RelativeLayout>

<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/camera_view"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <SurfaceView        android:id="@+id/cameraSurfaceView"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_gravity="center" />    <RelativeLayout        android:id="@+id/cameraButtonLayout"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:background="@android:color/transparent"        android:orientation="horizontal" >        <Button            android:id="@+id/cameraTakePicCancle"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_alignParentBottom="true"            android:layout_alignParentEnd="true"            android:layout_alignParentRight="true"            android:background="@color/RoyalBlue"            android:text="@string/camera_btn_back" />        <Button            android:id="@+id/cameraTakePic"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_alignParentBottom="true"            android:layout_marginEnd="10dp"            android:layout_marginRight="10dp"            android:layout_toLeftOf="@id/cameraTakePicCancle"            android:layout_toStartOf="@id/cameraTakePicCancle"            android:background="@color/RoyalBlue"            android:text="@string/camera_btn_takephoto" />    </RelativeLayout></FrameLayout>

  1 package com.example.demo_camera;  2   3 import java.util.List;  4   5 import android.app.Activity;  6 import android.graphics.PixelFormat;  7 import android.hardware.Camera;  8 import android.hardware.Camera.AutoFocusCallback;  9 import android.hardware.Camera.CameraInfo; 10 import android.hardware.Camera.Size; 11 import android.view.SurfaceHolder; 12 import android.view.SurfaceView; 13 import android.view.View; 14 import android.view.View.OnClickListener; 15 import android.view.ViewGroup; 16 import android.widget.Button; 17  18 public class CameraView { 19     // Private Constants /////////////////////////////////////////////////////// 20  21     // Public Variables //////////////////////////////////////////////////////// 22  23     // Member Variables //////////////////////////////////////////////////////// 24     private ViewGroup            mView; 25     private Activity            mActivity; 26  27     private Button                mBtnTakePhoto; 28     private Button                mBtnBack; 29     private SurfaceView            mSurfaceView; 30  31     private Camera                mCamera; 32     private Camera.Parameters    mParameters; 33     private CameraInfo            mCameraInfo; 34  35     private int                    mDegree; 36     private int                    mScreenWidth; 37     private int                    mScreenHeight; 38  39     // Constructors //////////////////////////////////////////////////////////// 40     public CameraView(Activity mActivity, ViewGroup mView) { 41         this.mActivity = mActivity; 42         this.mView = mView; 43         initCameraView(); 44         initCameraEvent(); 45     } 46  47     // Class Methods /////////////////////////////////////////////////////////// 48  49     // Private Methods ///////////////////////////////////////////////////////// 50     private void initCameraView() { 51         mBtnTakePhoto = (Button) mView.findViewById(R.id.cameraTakePic); 52         mBtnBack = (Button) mView.findViewById(R.id.cameraTakePicCancle); 53         mSurfaceView = (SurfaceView) mView.findViewById(R.id.cameraSurfaceView); 54  55     } 56  57     private void initCameraEvent() { 58  59         mSurfaceView.getHolder().setKeepScreenOn(true);// 屏幕常亮 60         mSurfaceView.getHolder().addCallback(new SurfaceCallback());// 为surfaceHolder添加回调 61         mSurfaceView.getHolder().setFormat(PixelFormat.TRANSPARENT); 62  63         mBtnTakePhoto.setOnClickListener(new OnClickListener() { 64  65             @Override 66             public void onClick(View v) { 67                 // TODO Auto-generated method stub 68                 // if (mCamera != null) { 69             } 70         }); 71  72         mBtnBack.setOnClickListener(new OnClickListener() { 73  74             @Override 75             public void onClick(View v) { 76                 // TODO Auto-generated method stub 77  78             } 79         }); 80     } 81  82     private final class SurfaceCallback implements SurfaceHolder.Callback { // 回调中包含三个重写方法，看方法名即可知道是干什么的 83  84         @Override 85         public void surfaceCreated(SurfaceHolder holder) { // 创建预览画面处理 86             // TODO Auto-generated method stub 87             int nNum = Camera.getNumberOfCameras(); // 根据摄像头的id找前后摄像头 88             if (nNum == 0) { 89                 // 没有摄像头 90                 return; 91             } 92  93             for (int i = 0; i < nNum; i++) { 94                 CameraInfo info = new CameraInfo(); // camera information 对象 95                 Camera.getCameraInfo(i, info);// 获取information 96                 if (info.facing == CameraInfo.CAMERA_FACING_BACK) { // 后摄像头 97                     startPreview(info, i, holder); // 设置preview的显示属性 98                     return; 99                 }100             }101 102         }103 104         @Override105         public void surfaceChanged(SurfaceHolder holder, int format, int width,106                 int height) { // 预览画面有变化时进行如下处理107             // TODO Auto-generated method stub108             if (mCamera == null) {109                 return;110             }111 112             mCamera.autoFocus(new AutoFocusCallback() { // 增加自动对焦113                 @Override114                 public void onAutoFocus(boolean success, Camera camera) {115                     // TODO Auto-generated method stub116                     if (success) { // 如果自动对焦成功117                         mCamera.cancelAutoFocus(); // 关闭自动对焦，下次有变化时再重新打开自动对焦,这句不能少118                     }119                 }120             });121         }122 123         @Override124         public void surfaceDestroyed(SurfaceHolder holder) { // surfaceView关闭处理以下方法125             // TODO Auto-generated method stub126             if (mCamera != null) {127                 mCamera.stopPreview();128                 mCamera.release(); // 释放照相机 不能少129                 mCamera = null;130                 mCameraInfo = null;131             }132         }133 134     }135 136     private Size getOptimalSize(int nDisplayWidth, int nDisplayHeight,137             List<Size> sizes, double targetRatio) { // 这里是我的一个计算显示尺寸的方法，可以自己去设计138         final double ASPECT_TOLERANCE = 0.001;139         if (sizes == null)140             return null;141 142         Size optimalSize = null;143         double minDiff = Double.MAX_VALUE;144 145         int targetHeight = Math.min(nDisplayWidth, nDisplayHeight);146         for (Size size : sizes) {147             double ratio = (double) size.width / size.height;148             if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)149                 continue;150             if (Math.abs(size.height - targetHeight) < minDiff) {151                 optimalSize = size;152                 minDiff = Math.abs(size.height - targetHeight);153             }154         }155         if (optimalSize == null) {156             minDiff = Double.MAX_VALUE;157             for (Size size : sizes) {158                 if (Math.abs(size.height - targetHeight) < minDiff) {159                     optimalSize = size;160                     minDiff = Math.abs(size.height - targetHeight);161                 }162             }163         }164         return optimalSize;165     }166 167     // Public Methods //////////////////////////////////////////////////////////168     public void show() {169         mView.setVisibility(View.VISIBLE);170         mSurfaceView.setVisibility(View.VISIBLE); //171     }172 173     public void hideCamera() {174         mView.setVisibility(View.GONE);175         mSurfaceView.setVisibility(View.GONE); //176     }177 178     public final ViewGroup getViewGroup() {179         return mView;180     }181 182     public void initScreenSize(int nWidth, int nHeight) { // 设置屏幕的宽与高183         ViewGroup.LayoutParams lp = mSurfaceView.getLayoutParams();184         lp.width = nWidth;185         lp.height = nHeight;186         mSurfaceView.setLayoutParams(lp);187 188         mScreenWidth = nWidth;189         mScreenHeight = nHeight;190     }191 192     public void startPreview(CameraInfo info, int cameraId, SurfaceHolder holder) {// 在回调中调用设置预览的属性193         try {194 195             mCameraInfo = info;196 197             mCamera = Camera.open(cameraId);198 199             mCamera.setPreviewDisplay(holder); // 设置用于显示拍照影像的SurfaceHolder对象200             mCamera.setDisplayOrientation(90); // 设置显示的方向，这里手机是竖直为正向90度，可以自己写个方法来根据屏幕旋转情况获取到相应的角度201 202             {203                 mParameters = mCamera.getParameters();204 205                 // PictureSize 获取支持显示的尺寸 因为支持的显示尺寸是和设备有关，所以需要获取设备支持的尺寸列表206                 // 另外因为是预览画面是全屏显示，所以显示效果也和屏幕的分辨率也有关系，为了最好的适应屏幕，建议选取207                 // 与屏幕最接近的宽高比的尺寸208                 List<Size> listPictureSizes = mParameters209                         .getSupportedPictureSizes();210 211                 Size sizeOptimalPicture = getOptimalSize(mScreenWidth,212                         mScreenHeight, listPictureSizes, (double) mScreenWidth213                                 / mScreenHeight);214                 mParameters.setPictureSize(sizeOptimalPicture.width,215                         sizeOptimalPicture.height);216 217                 // PreviewSize218                 List<Camera.Size> ListPreviewSizes = mParameters219                         .getSupportedPreviewSizes();220 221                 Size sizeOptimalPreview = getOptimalSize(222                         sizeOptimalPicture.width, sizeOptimalPicture.height,223                         ListPreviewSizes, (double) sizeOptimalPicture.width224                                 / sizeOptimalPicture.height);225                 mParameters.setPreviewSize(sizeOptimalPreview.width,226                         sizeOptimalPreview.height);227 228                 // 这里就是有的设备不支持Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE连续自动对焦这个字段，所以做个判断229                 List<String> lstFocusModels = mParameters230                         .getSupportedFocusModes();231                 for (String str : lstFocusModels) {232                     if (str.equals(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {233                         mParameters234                                 .setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);235                         break;236                     }237                 }238 239                 mCamera.setParameters(mParameters);240             }241 242             mCamera.startPreview(); // 开始预览243 244         } catch (Exception e) {245             e.printStackTrace();246         }247     }248 }

 1 package com.example.demo_camera; 2  3 import android.app.Activity; 4 import android.os.Bundle; 5 import android.util.DisplayMetrics; 6 import android.view.Menu; 7 import android.view.MenuItem; 8 import android.view.View; 9 import android.view.Window;10 import android.view.View.OnClickListener;11 import android.view.ViewGroup;12 import android.view.WindowManager;13 import android.widget.Button;14 15 public class MainActivity extends Activity {16 17     Button        mBtnCamera;18     ViewGroup    mVgCamera;19     CameraView    mCameraView;20 21     @Override22     protected void onCreate(Bundle savedInstanceState) {23         super.onCreate(savedInstanceState);24 25         // 全屏显示要隐藏标题栏状态栏26         // hide title bar27         requestWindowFeature(Window.FEATURE_NO_TITLE);28         // hide status bar29         int flag = WindowManager.LayoutParams.FLAG_FULLSCREEN;30         Window window = this.getWindow();31         window.setFlags(flag, flag);32 33         setContentView(R.layout.activity_main);34 35         mBtnCamera = (Button) findViewById(R.id.main_btn);36         mVgCamera = (ViewGroup) findViewById(R.id.camera_layout);37         mCameraView = new CameraView(this, mVgCamera);38 39         mBtnCamera.setOnClickListener(new OnClickListener() {40 41             @Override42             public void onClick(View v) {43                 // TODO Auto-generated method stub44                 mBtnCamera.setVisibility(View.GONE);45                 mVgCamera.setVisibility(View.VISIBLE);46 47                 setCameraSize();48 49             }50         });51     }52 53     private void setCameraSize() {54 55         ViewGroup.LayoutParams params = mCameraView.getViewGroup()56                 .getLayoutParams();57         DisplayMetrics dm = new DisplayMetrics();58         this.getWindowManager().getDefaultDisplay().getMetrics(dm);// 获得屏幕尺寸59         params.width = dm.widthPixels;60         params.height = dm.heightPixels;61 62         mCameraView.getViewGroup().setLayoutParams(params);63         mCameraView.initScreenSize(params.width, params.height);64         mCameraView.show();65     }66 67     @Override68     public boolean onCreateOptionsMenu(Menu menu) {69         // Inflate the menu; this adds items to the action bar if it is present.70         getMenuInflater().inflate(R.menu.main, menu);71         return true;72     }73 74     @Override75     public boolean onOptionsItemSelected(MenuItem item) {76         // Handle action bar item clicks here. The action bar will77         // automatically handle clicks on the Home/Up button, so long78         // as you specify a parent activity in AndroidManifest.xml.79         int id = item.getItemId();80         if (id == R.id.action_settings) {81             return true;82         }83         return super.onOptionsItemSelected(item);84     }85 }

<?xml version="1.0" encoding="utf-8"?><resources>    <string name="app_name">Demo_camera</string>    <string name="hello_world">Hello world!</string>    <string name="action_settings">Settings</string>    <string name="camera_btn_back">Back</string>    <string name="camera_btn_takephoto">TakePic</string>    <string name="main_btn_open_camera">Open Camera</string>    <color name="RoyalBlue">#4169E1</color></resources>