使用android.hardware.camera2访问相机

debugcn 发表于 Dev

马修·斯坦哈特（Matthew Steinhardt）

我想创建一个应用程序，使我可以控制相机上的闪光灯，但是我对如何执行此操作的研究导致了很多使用最近贬值的android.hardware.cameraapi的示例。有人可以向我指出如何androird.hardware.camera2制作一个简单的手电筒应用程序的正确方向吗？

乔舒亚·乔什（Josua Josh）

如果您只想制作一个简单的手电筒应用程序，则应编辑问题。将相机与新的android.hardware.camera2配合使用会更加复杂。

我试图使用android studio和nexus lg 5x制作相机预览应用，但没有成功。

相反，如果您只想打开闪光灯，请使用以下代码：

void torch(){
    /* turn on the flash light */
    CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
        String[] cameraID = new String[]{};
        cameraID = cameraManager.getCameraIdList();
        for(int i = 0; i<cameraID.length; i++){
            Log.e(TAG,cameraID[i]);
        }

        /* camera id is 0 and 1. 0 is the back camera, 1 is the front camera */
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            cameraManager.setTorchMode(cameraID[0],true); 
            //true means turned on, false, means turned off.
        }

    } catch (CameraAccessException e) {
        e.printStackTrace();
    }

}

显现：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.test">
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-feature android:name="android.hardware.camera2.full" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/MaterialTheme">

    <activity
        android:name=".MainActivity"
        android:screenOrientation="portrait"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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


</application>

MainActivity.java：

package com.example.test;

import android.app.Activity;
import android.graphics.Camera;
import android.hardware.camera2.params.InputConfiguration;
import android.os.Build;
import android.os.Bundle;

public class MainActivity extends Activity {

private final static String TAG = "Camera2testJ";
private Size mPreviewSize;

private TextureView mTextureView;
private CameraDevice mCameraDevice;
private CaptureRequest.Builder mPreviewBuilder;
private CameraCaptureSession mPreviewSession;

private Button mBtnShot;

private static final SparseIntArray ORIENTATIONS = new SparseIntArray();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.activity_main);

    mTextureView = (TextureView)findViewById(R.id.texture);
    mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);

    mBtnShot = (Button)findViewById(R.id.btn_takepicture);
    mBtnShot.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            Log.e(TAG, "mBtnShot clicked");
            torch();
        }

    });

}

void torch(){
    /* try the flash light */
    CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);;
    try {
        String[] cameraID = new String[]{};
        cameraID = cameraManager.getCameraIdList();
        for(int i = 0; i<cameraID.length; i++){
            Log.e(TAG,cameraID[i]);
        }

        /* camera id is 0 and 1. which one is the front or the back camera? */
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            cameraManager.setTorchMode(cameraID[0],true);
        }

    } catch (CameraAccessException e) {
        e.printStackTrace();
    }

}

布局activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextureView
        android:id="@+id/texture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true" />

    <Button
        android:id="@+id/btn_takepicture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="@string/picture"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

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