如何在mainactivity中停止和重新启动java代码（QRcode、Android、Vision）

Question

我找到了一个很好的QRcode/条形码识别代码——它工作得很好，但是！它不停地工作。检测到的代码以条形码文本显示，但方法/proces/camera（initialiseDetectorsAndSources（））仍在工作。我尝试了一些方法来阻止它，并找到了那个摄像源。release（）在某种程度上起作用了：相机停止了，但我不确定探测器进程是否仍在后台某处运行？。然后，我添加了一个按钮，再次启动initialiseDetectorsAndSources（）方法=

如何在创建代码后停止代码的进程或识别？

如何重新开始读取下一个qrcode的过程？

我可以将initialiseDetectorsAndSources（）方法移动到mainactivity之外的新类吗。。。这个方法在程序启动后开始-我想在。。。例如，我按下一个按钮。

谢谢你的帮助：）

这是我的主要活动。爪哇：

package net.ginekolog.qrtest01;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.media.AudioManager;
import android.media.ToneGenerator;
import android.os.Bundle;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;

import java.io.IOException;
import java.util.Objects;

public class MainActivity extends AppCompatActivity {

    private SurfaceView surfaceView;
    private BarcodeDetector barcodeDetector;
    private CameraSource cameraSource;
    private static final int REQUEST_CAMERA_PERMISSION = 201;
    private ToneGenerator toneGen1;
    private TextView barcodeText;
    private String barcodeData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        toneGen1 = new ToneGenerator(AudioManager.STREAM_MUSIC, 100);
        surfaceView = findViewById(R.id.surface_view);
        barcodeText = findViewById(R.id.barcode_text);

        Button button = (Button) findViewById(R.id.startQRscanButton);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Do something in response to button click
                initialiseDetectorsAndSources();
                Toast.makeText(getApplicationContext(), "button clicked", Toast.LENGTH_LONG).show();
            }
                    });

        // initialiseDetectorsAndSources();
        Toast.makeText(getApplicationContext(), "onCreate : end", Toast.LENGTH_LONG).show();
    }

    private void initialiseDetectorsAndSources() {

        Toast.makeText(getApplicationContext(), "iD&S : Barcode scanner started", Toast.LENGTH_SHORT).show();

        barcodeDetector = new BarcodeDetector.Builder(this)
                .setBarcodeFormats(Barcode.ALL_FORMATS)
                .build();

        cameraSource = new CameraSource.Builder(this, barcodeDetector)
                .setRequestedPreviewSize(1024, 768)//1920x1080
                .setAutoFocusEnabled(true)//you should add this feature
                //.setRequestedFps(10)//default is 30
                .build();

        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {
                        cameraSource.start(surfaceView.getHolder());
                    } else {
                        ActivityCompat.requestPermissions(MainActivity.this, new
                                String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

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

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop();
            }
        });

        barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
            @Override
            public void release() {
                Toast.makeText(getApplicationContext(), "release : To prevent memory leaks barcode scanner has been stopped", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void receiveDetections(Detector.Detections<Barcode> detections) {
                final SparseArray<Barcode> barcodes = detections.getDetectedItems();
                if (barcodes.size() != 0) {

                    barcodeText.post(new Runnable() {

                        @Override
                        public void run() {

                            if (barcodes.valueAt(0).email != null)
                            {
                                barcodeText.removeCallbacks(null);
                                barcodeData = barcodes.valueAt(0).email + " - email ";
                                // barcodeData = barcodes.valueAt(0).email.address;
                                // barcodeData = barcodes.valueAt(0).rawValue;
                                barcodeText.setText(barcodeData);
                                toneGen1.startTone(ToneGenerator.TONE_CDMA_PIP, 1150);
                                // stop kamera
                                cameraSource.release();
                            }
                            else
                            {
                                barcodeData = barcodes.valueAt(0).displayValue + " display value ";
                                barcodeText.setText(barcodeData);
                                toneGen1.startTone(ToneGenerator.TONE_CDMA_PIP, 1150);
                                // stop ... how ?
                                // cameraSource.stop();
                                // barcodes.clear();
                                cameraSource.release();
                                // barcodeDetector.release();
                                // surfaceView.releasePointerCapture();
                                // surfaceView.clearFocus();
                                // release();
                            }
                        }
                    });

                }
            }
        });
    };

    @Override
    protected void onPause() {
        super.onPause();
        Objects.requireNonNull(getSupportActionBar()).show();
        cameraSource.release();
    }

    @Override
    protected void onResume() {
        super.onResume();
        Objects.requireNonNull(getSupportActionBar()).show();
        initialiseDetectorsAndSources();
    }
}

Answer 1

到目前为止，还没有人试图回答这个问题，所以我试图找到一些解决方案。我发现：这项活动的一部分是在后台进行的，所以我认为最好的办法是把整个班级分成单独的活动，然后从主要活动中调用它。当这个活动完成后，我将回到主要活动，从而完成相机和条形码检测器的背景活动。好的链接如何停止活动：如何关闭活动并返回到android中的上一个活动