导入android.hardware.camera2时无法解析导入

Question

import android.content.Context;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.graphics.Camera;
import android.hardware.camera2;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.appindexing.Thing;
import com.google.android.gms.common.api.GoogleApiClient;
import java.security.Policy;

public class FlashLightActivit extends AppCompatActivity {

    //flag to detect flash is on or off
    public boolean isLighOn = false;

    public Camera camera;

    public Button button;
    /**
     * ATTENTION: This was auto-generated to implement the App Indexing API.
     * See https://g.co/AppIndexing/AndroidStudio for more information.
     */
    private GoogleApiClient client;

    @Override
    protected void onStop() {
        super.onStop();// ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        AppIndex.AppIndexApi.end(client, getIndexApiAction());

        if (camera != null) {
            camera.relese();
        }
        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        client.disconnect();
    }

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

        Context context = this;
        PackageManager pm = context.getPackageManager();

        // if device support camera?
        if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
            Log.e("err", "Device has no camera!");
            return;
        }

        camera = Camera.open();
        final Policy.Parameters p = camera.getParameters();

        button.setOnClickListener(new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialogInterface, int i) {

            }

            @Override
            public int hashCode() {
                return super.hashCode();
            }

            @Override
            public void onClick(View arg0) {

                if (isLighOn) {

                    Log.i("info", "torch is turn off!");

                    p.setFlashMode(android.hardware.Camera.Parameters.FLASH_MODE_OFF);
                    camera.setParameters(p);
                    camera.stopPreview();
                    isLighOn = false;

                } else {

                    Log.i("info", "torch is turn on!");

                    p.setFlashMode(android.hardware.Camera.Parameters.FLASH_MODE_TORCH);

                    camera.setParameters(p);
                    camera.startPreview();
                    isLighOn = true;

                }

            }
        });

        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
    }

    /**
     * ATTENTION: This was auto-generated to implement the App Indexing API.
     * See https://g.co/AppIndexing/AndroidStudio for more information.
     */
    public Action getIndexApiAction() {
        Thing object = new Thing.Builder()
                .setName("FlashLightActivit Page") // TODO: Define a title for the content shown.
                // TODO: Make sure this auto-generated URL is correct.
                .setUrl(Uri.parse("http://[ENTER-YOUR-URL-HERE]"))
                .build();
        return new Action.Builder(Action.TYPE_VIEW)
                .setObject(object)
                .setActionStatus(Action.STATUS_TYPE_COMPLETED)
                .build();
    }

    @Override
    public void onStart() {
        super.onStart();

        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        client.connect();
        AppIndex.AppIndexApi.start(client, getIndexApiAction());
    }
}