Android camera打开摄像头、预览

一、activity_main.xml代码：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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">

    <SurfaceView
        android:id="@+id/surface_view"
        android:layout_width="353dp"
        android:layout_height="621dp"
        android:layout_marginStart="24dp"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="24dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/buttonOpen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:layout_marginBottom="16dp"
        android:text="打开摄像头"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/surface_view" />

    <Button
        android:id="@+id/button5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="24dp"
        android:layout_marginBottom="16dp"
        android:text="Button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/buttonOpen"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/surface_view" />

    <Button
        android:id="@+id/button6"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="24dp"
        android:layout_marginBottom="16dp"
        android:text="Button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/buttonOpen"
        app:layout_constraintTop_toBottomOf="@+id/surface_view" />


</androidx.constraintlayout.widget.ConstraintLayout>

二、AndroidManifest.xml代码：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">
    <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:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.FourthApp"
        tools:targetApi="31">
        <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>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

</manifest>

三、MainActivity.java代码：

public class MainActivity extends AppCompatActivity {
    private Camera fCamera;
    private boolean isPreview = false;
    private SurfaceView surfaceView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        surfaceView=findViewById(R.id.surface_view);

        //surfaceView.setVisibility(View.INVISIBLE);
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_DENIED) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                requestPermissions(new String[]{Manifest.permission.CAMERA}, 11);
            }
        }

        surfaceView.getLayoutParams().width=720;
        surfaceView.getLayoutParams().height=720;

        SurfaceView mSurfaceView = (SurfaceView) findViewById(R.id.surface_view);
        SurfaceHolder mSurfaceHolder = mSurfaceView.getHolder();

        mSurfaceHolder.setFormat(PixelFormat.TRANSPARENT);

        mSurfaceHolder.addCallback(mSurfaceCallback);
    }

    private SurfaceHolder.Callback mSurfaceCallback = new SurfaceHolder.Callback() {


        @Override
        public void surfaceCreated(SurfaceHolder surfaceHolder) {
            try {
                fCamera = Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK);
                fCamera.setPreviewDisplay(surfaceHolder);
                fCamera.startPreview();
                isPreview = true;
            } catch (IOException e) {
                Log.e("boy", e.toString());
            }
        }

        @Override
        public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) {

        }

        @Override
        public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
            if(fCamera != null){
                if(isPreview){
                    fCamera.stopPreview();
                    fCamera.release();
                }
            }
        }
    };



}

四、运行效果：