1.控制手電筒開關的工具類：

public class FlashUtils {
    private CameraManager manager;
    private Camera mCamera = null;
    private Context context;
    private boolean status = false;//記錄手電筒狀態
FlashUtils(Context context){
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            manager 
 
= (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
}
        this.context = context;
}

    //開啟手電筒
public void open() {
        if(status){//如果已經是開啟狀態，不需要開啟
return;
}
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            try {
                manager.setTorchMode("0"
 
, true);
} catch (Exception e) {
                e.printStackTrace();
}
        } else {
            PackageManager packageManager = context.getPackageManager();
FeatureInfo[] features = packageManager.getSystemAvailableFeatures();
            for (FeatureInfo featureInfo : features) {
                if 
 
(PackageManager.FEATURE_CAMERA_FLASH.equals(featureInfo.name)) { // 判斷裝置是否支援閃光燈
if (null == mCamera) {
                        mCamera = Camera.open();
}
                    Camera.Parameters parameters = mCamera.getParameters();
parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
mCamera.setParameters(parameters);
mCamera.startPreview();
}
            }
        }
        status = true;//記錄手電筒狀態為開啟
}

    //關閉手電筒
public void close() {
        if(!status){//如果已經是關閉狀態，不需要開啟
return;
}
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            try {
                manager.setTorchMode("0", false);
} catch (CameraAccessException e) {
                e.printStackTrace();
}
        } else {
            if (mCamera != null) {
                mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
        }
        status = false;//記錄手電筒狀態為關閉
}

    //改變手電筒狀態
public void converse(){
        if(status){
            close();
}else{
            open();
}
    }
}

2.使用方法：

FlashUtils utils = new FlashUtils(this);
utils.open();//開啟手電筒
//        utils.close();//關閉手電筒

3.示例程式已上傳：