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android camera2 API初探打開攝像頭（自拍那個攝像頭）

发布时间：2022-03-27 20:16:49编辑：雪饮阅读（）

最近想要做一個系列的安卓端的音視頻的實踐，想的比較多，但是都知道安卓端是很麻煩的，特別音視頻這方面。那麽首先這裏我就先從打開自拍那個攝像頭，這裏也就是後置攝像頭后了。

環境：

android studio：

Android Studio Bumblebee | 2021.1.1 Patch 2

Build #AI-211.7628.21.2111.8193401, built on February 17, 2022

Runtime version: 11.0.11+9-b60-7590822 amd64

VM: OpenJDK 64-Bit Server VM by Oracle Corporation

Windows 10 10.0

GC: G1 Young Generation, G1 Old Generation

Memory: 1280M

Cores: 12

Registry: external.system.auto.import.disabled=true

Non-Bundled Plugins: com.intellij.marketplace (211.7628.36), edu.umontreal.hatchery (0.2.1), com.thoughtworks.gauge (211.6693.111)

真機：pixel4a

網絡上大多數文章介紹的都是camera那個api，而安卓官網早都有了camera2的api，那麽這裏我剛入門安卓，還沒有折騰過攝像頭，沒有想到第一次折騰就遇到一個過時的api。。。

而我這裏要適配的最低安卓版本是安卓9.安卓9也是要要求camera2的api（好像是）。

同樣的打開攝像頭是需要用戶授權的，好像是從安卓6開始就要動態授權了。

那麽這裏我沒有做動態授權，我是自己在app哪裏提前授權好攝像頭權限的。

聲明文件

那麽聲明文件AndroidManifest.xml中自然是需要聲名好攝像頭權限的：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">
  <uses-permission android:name="android.permission.CAMERA" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyApplication">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

佈局文件

接下來我需要一個SurfaceView用來顯示後置攝像頭打開后的畫面預覽，所以：

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
 <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:orientation="vertical">
         <SurfaceView
             android:id="@+id/sv"
             android:layout_width="200dp"
             android:layout_height="200dp" />
     </LinearLayout>
 
 </android.support.constraint.ConstraintLayout>

注意：這裏可能會報錯“Cannot resolve class android.support.constraint.ConstraintLayout”

這個真坑，折騰了我快一天了，沒有搞定，看好多文章縂說紛紜，甚至都有說是官方的一個bug，至今沒有修復的特別好。

但後來發現我不管他，照樣能在真機上面運行不崩潰。

java邏輯文件

在java這邊我僅僅判斷了沒有授權攝像頭權限就return，沒有過多在權限上做處理。

然後剩下的都是盡量精簡了的打開攝像頭的邏輯了（聯係到web端通過JavaScript打開攝像頭的邏輯就那個一兩行就搞定了。。。）

package com.example.myapplication;
 import android.Manifest;
 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.graphics.ImageFormat;
 import android.hardware.camera2.CameraAccessException;
 import android.hardware.camera2.CameraCaptureSession;
 import android.hardware.camera2.CameraCharacteristics;
 import android.hardware.camera2.CameraDevice;
 import android.hardware.camera2.CameraManager;
 import android.hardware.camera2.CaptureRequest;
 import android.media.ImageReader;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.support.v4.app.ActivityCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 import android.widget.Toast;
 import java.util.Arrays;
 
 public class MainActivity extends AppCompatActivity {
     private Handler childHandler, mainHandler;
     private CameraCaptureSession mCameraCaptureSession;
     private ImageReader mImageReader;
     private SurfaceView mSurfaceView;
     private SurfaceHolder mSurfaceHolder;
     private CameraDevice mCameraDevice;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         SurfaceViewInit();
     }
     public void SurfaceViewInit(){
         //視頻流渲染區域
         mSurfaceView = (SurfaceView) findViewById(R.id.sv);
         mSurfaceHolder = mSurfaceView.getHolder();
         mSurfaceHolder.setKeepScreenOn(true);
         mSurfaceHolder.addCallback(new SurfaceHolder.Callback() {
             @Override
             public void surfaceCreated(SurfaceHolder holder) { //SurfaceView创建
                 // 初始化Camera
                 initCamera2();
             }
 
             @Override
             public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
 
             }
 
             @Override
             public void surfaceDestroyed(SurfaceHolder holder) { //SurfaceView销毁
                 // 释放Camera资源
                 if (null != mCameraDevice) {
                     mCameraDevice.close();
                     MainActivity.this.mCameraDevice = null;
                 }
             }
         });
     }
     /**
      * 开始预览
      */
     private void takePreview() {
         try {
             // 创建预览需要的CaptureRequest.Builder
             final CaptureRequest.Builder previewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
             // 将SurfaceView的surface作为CaptureRequest.Builder的目标
             previewRequestBuilder.addTarget(mSurfaceHolder.getSurface());
 
             mImageReader = ImageReader.newInstance(1080, 1920, ImageFormat.JPEG,1);
 
             // 创建CameraCaptureSession，该对象负责管理处理预览请求和拍照请求
             mCameraDevice.createCaptureSession(Arrays.asList(mSurfaceHolder.getSurface(), mImageReader.getSurface()), new CameraCaptureSession.StateCallback() // ③
             {
                 @Override
                 public void onConfigured(CameraCaptureSession cameraCaptureSession) {
                     if (null == mCameraDevice) return;
                     // 当摄像头已经准备好时，开始显示预览
                     mCameraCaptureSession = cameraCaptureSession;
                     try {
                         // 自动对焦
                         previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
                         // 打开闪光灯
                         previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
                         // 显示预览
                         CaptureRequest previewRequest = previewRequestBuilder.build();
                         mCameraCaptureSession.setRepeatingRequest(previewRequest, null, childHandler);
                     } catch (CameraAccessException e) {
                         e.printStackTrace();
                     }
                 }
 
                 @Override
                 public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {
                     Toast.makeText(MainActivity.this, "配置失败", Toast.LENGTH_SHORT).show();
                 }
             }, childHandler);
         } catch (CameraAccessException e) {
             e.printStackTrace();
         }
     }
     /**
      * 摄像头创建监听
      */
     private CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
         @Override
         public void onOpened(CameraDevice camera) {//打开摄像头
             mCameraDevice = camera;
             //开启预览
             takePreview();
         }
 
         @Override
         public void onDisconnected(CameraDevice camera) {//关闭摄像头
             if (null != mCameraDevice) {
                 mCameraDevice.close();
                 MainActivity.this.mCameraDevice = null;
             }
         }
 
         @Override
         public void onError(CameraDevice camera, int error) {//发生错误
             Toast.makeText(MainActivity.this, "摄像头开启失败", Toast.LENGTH_SHORT).show();
         }
     };
     public void initCamera2(){
         CameraManager mCameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
         //攝像頭權限判斷
         if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
             Log.i("沒有獲取到攝像頭權限","");
             return;
         }
         HandlerThread handlerThread = new HandlerThread("Camera2");
         handlerThread.start();
         childHandler = new Handler(handlerThread.getLooper());
         mainHandler = new Handler(getMainLooper());
         //前置攝像頭，自拍用
         String mCameraID = "" + CameraCharacteristics.LENS_FACING_BACK;
         Log.i("攝像機id",mCameraID);
         try{
             mCameraManager.openCamera(mCameraID,stateCallback,mainHandler);
         }
         catch (CameraAccessException e) {
             e.printStackTrace();
         }
     }
 }

效果

关键字词：camera2,android,攝像頭,自拍

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