打开和关闭Android后置闪关灯

package fengxing.primer.study2;

import android.content.Context;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.widget.CompoundButton;
import android.widget.Switch;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

import java.util.List;

public class CameraActivity extends AppCompatActivity {

    private static final String TAG = CameraActivity.class.getSimpleName();
    //相机特新管理
    private CameraManager cameraManager;
    //回调函数
    private CameraManager.TorchCallback torchCallback;

    private String[] cameraList;
    //开关
    private Switch aSwitch;

    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);
        initFlashLight();
        initListener();
    }

    /**
     * 设置switch开关监听
     */
    private void initListener() {
        aSwitch = findViewById(R.id.switch_light);
        aSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @RequiresApi(api = Build.VERSION_CODES.M)
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                if (cameraList==null)return;
                try {
                    cameraManager.setTorchMode(cameraList[0],isChecked);
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                }
                Log.d(TAG, "onCheckedChanged: "+cameraList.toString());
            }
        });
    }

    /**
     * 初始化闪光灯
     */
    @RequiresApi(api = Build.VERSION_CODES.M)
    private void initFlashLight() {
        cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        torchCallback = new CameraManager.TorchCallback(){
            //闪关灯改变
            @Override
            public void onTorchModeChanged(@NonNull String cameraId, boolean enabled) {
                super.onTorchModeChanged(cameraId, enabled);
                Log.d(TAG, "onTorchModeChanged: "+cameraId+"   "+ enabled);
            }

            //闪关灯不可用
            @Override
            public void onTorchModeUnavailable(@NonNull String cameraId) {
                super.onTorchModeUnavailable(cameraId);
                Log.d(TAG, "onTorchModeUnavailable: ");
                Toast.makeText(getApplicationContext(),"电筒不可用",Toast.LENGTH_SHORT);
            }
        };

        //获取相机列表
        try {
           cameraList = cameraManager.getCameraIdList();
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }

        //使其在一个handle机制中运行
        cameraManager.registerTorchCallback(torchCallback,new Handler());
    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    protected void onDestroy() {
        super.onDestroy();
        cameraManager.unregisterTorchCallback(torchCallback);
    }
}