Android 实例讲解自定义Camera拍照和预览以及前后置摄像头切换

上一篇博文讲解了怎么去调用本地图片和调用系统拍照图片(http://blog.csdn.net/a123demi/article/details/40003695)的功能。

而本博文将通过实例实现自定义Camera的功效。具体功能如下：

1.实现自定义Camera拍照；

2.实现前后置摄像头的切换；

3.实现Camera拍照后图片缩小显示以及正常预览；

4.实现Camera拍照后图片保存；

在具体实现代码之前，我们先来了解一下Android api对实现自定义Camera的介绍。

根据api的介绍，对于Camera应用可以简单总结以下几个步骤。

1.检查Camera是否存在，并在AndroidManifest.xml中赋予相关的权限；

2.创建一个继承于SurfaceView并实现SurfaceHolder接口的Camera Preview类；

3.在2的基础上新建一个Camera Preview布局文件；

4.设置一个拍照的监听事件，例如单击按钮事件等；

5.实现拍照，并保存拍照后的图片到设备；

6.释放Camera，以方便其他应用可以使用。

下面将通过具体代码实现我们给出的三个功能。

一.相关的xml文件

1.AndroidManifest.xml相关配置以及相关权限，实现步骤一当中的权限配置

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.camerasurfacedemo"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="11"        android:targetSdkVersion="19" />    <uses-permission android:name="android.permission.CAMERA" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />    <uses-feature android:name="android.hardware.camera" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.example.camerasurfacedemo.MainActivity"            android:label="@string/app_name" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>                <activity android:name="com.example.camerasurfacedemo.CameraActivity"            ></activity>        <activity android:name="com.example.camerasurfacedemo.PreviewActivity"            ></activity>    </application></manifest>

2.activity_main.xml主函数入口，进入自定义Camera界面入口，实现拍照后图片缩小显示功能

<LinearLayout 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:gravity="center_horizontal"    android:orientation="vertical" >"    <Button        android:id="@+id/id_go_camera_btn"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:text="进入拍照界面" />    <ImageView        android:id="@+id/id_show_camera_iv"        android:layout_width="150dp"        android:layout_height="200dp"        android:gravity="center" />    <TextView        android:layout_width="match_parent"        android:layout_height="match_parent"        android:gravity="center"        android:text="拍照图片显示区域"        android:textColor="#FF0000"        android:textSize="20sp" /></LinearLayout>

3.activity_camera.xml自定义Camera preview布局，实现步骤2，该界面实现前后置摄像头切换以及自定义拍照等

<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"   ><LinearLayout    android:id="@+id/id_process_btns_ll"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="horizontal"    android:layout_alignParentTop="true"     >    <Button         android:id="@+id/id_switch_camera_btn"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:gravity="center"        android:text="切换前后摄像头"        />     <Button         android:id="@+id/id_capture_btn"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:gravity="center"        android:text="拍照"        /></LinearLayout>    <SurfaceView        android:id="@+id/id_area_sv"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_below="@id/id_process_btns_ll"        android:text="拍照区域" /></RelativeLayout>

4.activity_preview.xml实现拍照后图片放大预览

<LinearLayout 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="#000000"    android:orientation="vertical" >    <TextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:text="拍照图片预览"         android:textColor="#FF0000"        android:textSize="20sp"        />    <ImageView        android:id="@+id/id_preview_camera_iv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:gravity="center" /></LinearLayout>

二.java代码实现

1.帮助类HelpUtil.java

package com.example.camerasurfacedemo;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.text.SimpleDateFormat;import java.util.Date;import android.annotation.SuppressLint;import android.content.ContentResolver;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Matrix;import android.net.Uri;public class HelpUtil {/** * 根据图片路径获取本地图片的Bitmap *  * @param url * @return */public static Bitmap getBitmapByUrl(String url) {FileInputStream fis = null;Bitmap bitmap = null;try {fis = new FileInputStream(url);bitmap = BitmapFactory.decodeStream(fis);} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();bitmap = null;} finally {if (fis != null) {try {fis.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}fis = null;}}return bitmap;}/** * bitmap旋转90度 *  * @param bitmap * @return */public static Bitmap createRotateBitmap(Bitmap bitmap) {if (bitmap != null) {Matrix m = new Matrix();try {m.setRotate(90, bitmap.getWidth() / 2, bitmap.getHeight() / 2);// 90就是我们需要选择的90度Bitmap bmp2 = Bitmap.createBitmap(bitmap, 0, 0,bitmap.getWidth(), bitmap.getHeight(), m, true);bitmap.recycle();bitmap = bmp2;} catch (Exception ex) {System.out.print("创建图片失败！" + ex);}}return bitmap;}public static Bitmap getBitmapByUri(Uri uri,ContentResolver cr){Bitmap bitmap = null;try {bitmap = BitmapFactory.decodeStream(cr .openInputStream(uri));} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();bitmap = null;}return bitmap;}/** * 获取格式化日期字符串 * @param date * @return */@SuppressLint("SimpleDateFormat")public static String getDateFormatString(Date date) {if (date == null)date = new Date();String formatStr = new String();SimpleDateFormat matter = new SimpleDateFormat("yyyyMMdd_HHmmss");formatStr = matter.format(date);return formatStr;}}

2.主函数类MainActivity.java

package com.example.camerasurfacedemo;import android.app.Activity;import android.content.Intent;import android.net.Uri;import android.os.Bundle;import android.text.TextUtils;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;public class MainActivity extends Activity {private Button goCameraBtn;private ImageView showCameraIv;private static final int CAMERA_CODE = 1;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);goCameraBtn = (Button)this.findViewById(R.id.id_go_camera_btn);goCameraBtn.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {processGoCamera();}});showCameraIv = (ImageView)this.findViewById(R.id.id_show_camera_iv);showCameraIv.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {processShowCamera(v);}});}/** * 处理进入camera事件 */private void processGoCamera(){Intent intent = new Intent();intent.setClass(this, CameraActivity.class);startActivityForResult(intent,CAMERA_CODE);}/** * 处理图片跳转进入预览界面 */private void processShowCamera(View v){Intent intent = new Intent();intent.setClass(this, PreviewActivity.class);/** * 将图片url传给PreviewActivity */intent.putExtra("cameraUrl", v.getContentDescription().toString());startActivity(intent);}@Overridepublic void onActivityResult(int requestCode,int resultCode,Intent data){super.onActivityResult(requestCode, resultCode, data);if(RESULT_OK == resultCode){if(CAMERA_CODE == requestCode){/** * 获取activity返回的url */Uri uri = data.getData();String url = uri.toString().substring(uri.toString().indexOf("///")+2);if(url != null && !TextUtils.isEmpty(url)){showCameraIv.setContentDescription(url);showCameraIv.setImageBitmap(HelpUtil.getBitmapByUrl(url));}}}}}

注意：这里通过startActivityForResult(intent,CAMERA_CODE)跳转和 onActivityResult(int requestCode,int resultCode,Intent data)返回拍照后的图片路径信息

3.自定义Camera preview类CameraActivity.java

package com.example.camerasurfacedemo;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.util.Date;import android.annotation.SuppressLint;import android.app.Activity;import android.content.Context;import android.content.Intent;import android.content.pm.PackageManager;import android.graphics.ImageFormat;import android.hardware.Camera;import android.hardware.Camera.CameraInfo;import android.hardware.Camera.Parameters;import android.hardware.Camera.PictureCallback;import android.net.Uri;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.View;import android.view.View.OnClickListener;import android.view.Window;import android.widget.Button;public class CameraActivity extends Activity implements OnClickListener,SurfaceHolder.Callback {private static final String TAG = CameraActivity.class.getSimpleName();private static final int MEDIA_TYPE_IMAGE = 1;private Button switchCameraBtn, captureBtn;private SurfaceView surfaceSv;private SurfaceHolder mHolder;private Camera mCamera;// 0表示后置，1表示前置private int cameraPosition = 1;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);// 不显示标题this.requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.activity_camera);findById();initData();}/** * 初始化view */private void findById() {switchCameraBtn = (Button) this.findViewById(R.id.id_switch_camera_btn);captureBtn = (Button) this.findViewById(R.id.id_capture_btn);surfaceSv = (SurfaceView) this.findViewById(R.id.id_area_sv);switchCameraBtn.setOnClickListener(this);captureBtn.setOnClickListener(this);}/** * 初始化相关data */private void initData() {// 获得句柄mHolder = surfaceSv.getHolder();// 添加回调mHolder.addCallback(this);}@Overridepublic void onStart() {super.onStart();if (this.checkCameraHardware(this) && (mCamera == null)) {// 打开cameramCamera = getCamera();if (mHolder != null) {setStartPreview(mCamera,mHolder);}}}private Camera getCamera() {Camera camera = null;try {camera = Camera.open();} catch (Exception e) {// Camera is not available (in use or does not exist)camera = null;Log.e(TAG, "Camera is not available (in use or does not exist)");}return camera;}@Overridepublic void onPause() {super.onPause();/** * 记得释放camera，方便其他应用调用 */releaseCamera();}@Overridepublic void onDestroy() {super.onDestroy();}/** * 释放mCamera */private void releaseCamera() {if (mCamera != null) {mCamera.setPreviewCallback(null);mCamera.stopPreview();// 停掉原来摄像头的预览mCamera.release();mCamera = null;}}@Overridepublic void onClick(View v) {switch (v.getId()) {case R.id.id_switch_camera_btn:// 切换前后摄像头int cameraCount = 0;CameraInfo cameraInfo = new CameraInfo();cameraCount = Camera.getNumberOfCameras();// 得到摄像头的个数for (int i = 0; i < cameraCount; i++) {Camera.getCameraInfo(i, cameraInfo);// 得到每一个摄像头的信息if (cameraPosition == 1) {// 现在是后置，变更为前置if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {/** * 记得释放camera，方便其他应用调用 */releaseCamera();// 打开当前选中的摄像头mCamera = Camera.open(i);// 通过surfaceview显示取景画面setStartPreview(mCamera,mHolder);cameraPosition = 0;break;}} else {// 现在是前置， 变更为后置if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {/** * 记得释放camera，方便其他应用调用 */releaseCamera();mCamera = Camera.open(i);setStartPreview(mCamera,mHolder);cameraPosition = 1;break;}}}break;case R.id.id_capture_btn:// 拍照,设置相关参数Camera.Parameters params = mCamera.getParameters();params.setPictureFormat(ImageFormat.JPEG);params.setPreviewSize(800, 400);// 自动对焦params.setFocusMode(Parameters.FOCUS_MODE_AUTO);mCamera.setParameters(params);mCamera.takePicture(null, null, picture);break;}}@Overridepublic void surfaceCreated(SurfaceHolder holder) {setStartPreview(mCamera,mHolder);}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {// If your preview can change or rotate, take care of those events here.// Make sure to stop the preview before resizing or reformatting it.if (mHolder.getSurface() == null) {// preview surface does not existreturn;}// stop preview before making changestry {mCamera.stopPreview();} catch (Exception e) {// ignore: tried to stop a non-existent preview}// set preview size and make any resize, rotate or// reformatting changes here// start preview with new settingssetStartPreview(mCamera,mHolder);}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {// 当surfaceview关闭时，关闭预览并释放资源/** * 记得释放camera，方便其他应用调用 */releaseCamera();holder = null;surfaceSv = null;}/** * 创建png图片回调数据对象 */PictureCallback picture = new PictureCallback() {@Overridepublic void onPictureTaken(byte[] data, Camera camera) {File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);if (pictureFile == null) {Log.d(TAG,"Error creating media file, check storage permissions: ");return;}try {FileOutputStream fos = new FileOutputStream(pictureFile);fos.write(data);fos.close();returnResult(pictureFile);} catch (FileNotFoundException e) {Log.d(TAG, "File not found: " + e.getMessage());} catch (IOException e) {Log.d(TAG, "Error accessing file: " + e.getMessage());}}};/** * Create a File for saving an image or video */private static File getOutputMediaFile(int type) {// To be safe, you should check that the SDCard is mounted// using Environment.getExternalStorageState() before doing this.File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"MyCameraApp");// This location works best if you want the created images to be shared// between applications and persist after your app has been uninstalled.// Create the storage directory if it does not existif (!mediaStorageDir.exists()) {if (!mediaStorageDir.mkdirs()) {Log.d("MyCameraApp", "failed to create directory");return null;}}// Create a media file nameString timeStamp = HelpUtil.getDateFormatString(new Date());File mediaFile;if (type == MEDIA_TYPE_IMAGE) {mediaFile = new File(mediaStorageDir.getPath() + File.separator+ "IMG_" + timeStamp + ".png");} else {return null;}return mediaFile;}/** Check if this device has a camera */private boolean checkCameraHardware(Context context) {if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {// this device has a camerareturn true;} else {// no camera on this devicereturn false;}}/** * activity返回式返回拍照图片路径 * @param mediaFile */private void returnResult(File mediaFile) {Intent intent = new Intent();intent.setData(Uri.fromFile(mediaFile));this.setResult(RESULT_OK, intent);this.finish();}/** * 设置camera显示取景画面,并预览 * @param camera */private void setStartPreview(Camera camera,SurfaceHolder holder){try {camera.setPreviewDisplay(holder);camera.startPreview();} catch (IOException e) {Log.d(TAG, "Error starting camera preview: " + e.getMessage());}}}

注意：

1.检查Camera是否存在

/** Check if this device has a camera */private boolean checkCameraHardware(Context context) {if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {// this device has a camerareturn true;} else {// no camera on this devicereturn false;}}

2.创建png格式的回调接口

/** * 创建png图片回调数据对象 */PictureCallback picture = new PictureCallback() {@Overridepublic void onPictureTaken(byte[] data, Camera camera) {File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);if (pictureFile == null) {Log.d(TAG,"Error creating media file, check storage permissions: ");return;}try {FileOutputStream fos = new FileOutputStream(pictureFile);fos.write(data);fos.close();returnResult(pictureFile);} catch (FileNotFoundException e) {Log.d(TAG, "File not found: " + e.getMessage());} catch (IOException e) {Log.d(TAG, "Error accessing file: " + e.getMessage());}}};

3.生成图片文件并保存

/** * Create a File for saving an image or video */private static File getOutputMediaFile(int type) {// To be safe, you should check that the SDCard is mounted// using Environment.getExternalStorageState() before doing this.File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"MyCameraApp");// This location works best if you want the created images to be shared// between applications and persist after your app has been uninstalled.// Create the storage directory if it does not existif (!mediaStorageDir.exists()) {if (!mediaStorageDir.mkdirs()) {Log.d("MyCameraApp", "failed to create directory");return null;}}// Create a media file nameString timeStamp = HelpUtil.getDateFormatString(new Date());File mediaFile;if (type == MEDIA_TYPE_IMAGE) {mediaFile = new File(mediaStorageDir.getPath() + File.separator+ "IMG_" + timeStamp + ".png");} else {return null;}return mediaFile;}

4.Camera一定要release

/** * 释放mCamera */private void releaseCamera() {if (mCamera != null) {mCamera.setPreviewCallback(null);mCamera.stopPreview();// 停掉原来摄像头的预览mCamera.release();mCamera = null;}}

5.Activity结果返回

/** * activity返回式返回拍照图片路径 * @param mediaFile */private void returnResult(File mediaFile) {Intent intent = new Intent();intent.setData(Uri.fromFile(mediaFile));this.setResult(RESULT_OK, intent);this.finish();}

4.图片正常预览PreviewActivity.java

package com.example.camerasurfacedemo;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.text.TextUtils;import android.view.Window;import android.widget.ImageView;import android.widget.Toast;public class PreviewActivity extends Activity {private ImageView previewCameraIv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);this.requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.activity_preview);previewCameraIv = (ImageView)this.findViewById(R.id.id_preview_camera_iv);Intent intent = this.getIntent();String cameraUrl = intent.getStringExtra("cameraUrl").toString();if(cameraUrl != null && !TextUtils.isEmpty(cameraUrl)){previewCameraIv.setImageBitmap(HelpUtil.getBitmapByUrl(cameraUrl));}else{Toast.makeText(this, "图片路径错误", Toast.LENGTH_SHORT).show();}}}

以上就是本博文的所有内容，谢谢品读。

源码路径：http://download.csdn.net/detail/a123demi/8029265