如何在 Android 中使用 CAMView 库读取二维码？

CAMView Library 是一种用于访问用户设备摄像头的简单解决方案。通过使用这个库，我们可以访问用户的相机，并使用内置的 ZXing 解码引擎来执行相机的许多功能，例如扫描条形码。该库包含一组准备好放入您的布局的组件，以便即时访问如此多的功能。该库处理低级例程，例如相机、配置、流媒体、方向等等。我们只需要按照一些基本步骤来使用这个库。

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重要方法

Methods	Description
onScannerStarted()	This method can be used when the scanner is started.
onScannerStopped()	This method is called when the scanner is stopped.
onScannerError()	This method is used when the scanner gives some error.
onCodeScanned()	This method is called when the scanner scans the data from the camera.

CAMView 库的实现

使用这个库，我们将创建一个简单的二维码扫描应用程序，它将扫描二维码中的数据并将其显示在 TextView 中。下面给出了一个示例 GIF，以了解我们将在本文中做什么。请注意，我们将使用Java语言来实现这个项目。

分步实施

第 1 步：创建一个新项目

要在 Android Studio 中创建新项目，请参阅如何在 Android Studio 中创建/启动新项目。请注意，选择Java作为编程语言。

第 2 步：在 build.gradle(Module:app) 中添加依赖项

导航到Gradle Scripts > build.gradle(Module:app)并在依赖项部分添加以下依赖项。

implementation (‘eu.livotov.labs.android:CAMView:2.0.1@aar’) {transitive=true}

现在同步选项将出现在右上角单击立即同步选项。

第三步：修改字符串.xml文件

下面是字符串.xml文件的代码。

XML

    GFG APP
    Toggle Flash
    Settings
    Scanned Data

第 4 步：在清单文件中为相机添加权限

我们正在清单文件中添加摄像头和振动权限。导航到应用程序 > 清单以找到AndroidManifest.xml 。下面是 AndroidManifest.xml 的代码片段

步骤 5：使用 activity_main.xml 文件

导航到app > res > layout > activity_main.xml并将以下代码添加到该文件中。下面是activity_main.xml文件的代码。

第 6 步：使用 MainActivity。 Java文件

导航到应用程序 > Java > 您的应用程序包名称 > MainActivity。 Java文件。下面是MainActivity 的代码。 Java文件。代码中添加了注释以更详细地理解代码。

Java

import android.content.pm.PackageManager;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
  
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
  
import eu.livotov.labs.android.camview.ScannerLiveView;
import eu.livotov.labs.android.camview.scanner.decoder.zxing.ZXDecoder;
  
import static android.Manifest.permission.CAMERA;
import static android.Manifest.permission.VIBRATE;
  
public class MainActivity extends AppCompatActivity {
    private ScannerLiveView camera;
    private TextView scannedTV;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
  
        // check permission method is to check that the
        // camera permission is granted by user or not.
        // request permission method is to request the
        // camera permission if not given.
        if (checkPermission()) {
            // if permission is already granted display a toast message
            Toast.makeText(this, "Permission Granted..", Toast.LENGTH_SHORT).show();
        } else {
            requestPermission();
        }
  
        // initialize scannerLiveview and textview.
        scannedTV = findViewById(R.id.idTVscanned);
        camera = (ScannerLiveView) findViewById(R.id.camview);
  
        camera.setScannerViewEventListener(new ScannerLiveView.ScannerViewEventListener() {
            @Override
            public void onScannerStarted(ScannerLiveView scanner) {
                // method is called when scanner is started
                Toast.makeText(MainActivity.this, "Scanner Started", Toast.LENGTH_SHORT).show();
            }
  
            @Override
            public void onScannerStopped(ScannerLiveView scanner) {
                // method is called when scanner is stoped.
                Toast.makeText(MainActivity.this, "Scanner Stopped", Toast.LENGTH_SHORT).show();
            }
  
            @Override
            public void onScannerError(Throwable err) {
                // method is called when scanner gives some error.
                Toast.makeText(MainActivity.this, "Scanner Error: " + err.getMessage(), Toast.LENGTH_SHORT).show();
            }
  
            @Override
            public void onCodeScanned(String data) {
                // method is called when camera scans the
                // qr code and the data from qr code is
                // stored in data in string format.
                scannedTV.setText(data);
            }
        });
    }
  
    @Override
    protected void onResume() {
        super.onResume();
        ZXDecoder decoder = new ZXDecoder();
        // 0.5 is the area where we have
        // to place red marker for scanning.
        decoder.setScanAreaPercent(0.8);
        // below method will set secoder to camera.
        camera.setDecoder(decoder);
        camera.startScanner();
    }
  
    @Override
    protected void onPause() {
        // on app pause the
        // camera will stop scanning.
        camera.stopScanner();
        super.onPause();
    }
  
    private boolean checkPermission() {
        // here we are checking two permission that is vibrate
        // and camera which is granted by user and not.
        // if permission is granted then we are returning
        // true otherwise false.
        int camera_permission = ContextCompat.checkSelfPermission(getApplicationContext(), CAMERA);
        int vibrate_permission = ContextCompat.checkSelfPermission(getApplicationContext(), VIBRATE);
        return camera_permission == PackageManager.PERMISSION_GRANTED && vibrate_permission == PackageManager.PERMISSION_GRANTED;
    }
  
  
    private void requestPermission() {
        // this method is to request
        // the runtime permission.
        int PERMISSION_REQUEST_CODE = 200;
        ActivityCompat.requestPermissions(this, new String[]{CAMERA, VIBRATE}, PERMISSION_REQUEST_CODE);
    }
  
    @Override
    public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
        // this method is called when user
        // allows the permission to use camera.
        if (grantResults.length > 0) {
            boolean cameraaccepted = grantResults[0] == PackageManager.PERMISSION_GRANTED;
            boolean vibrateaccepted = grantResults[1] == PackageManager.PERMISSION_GRANTED;
            if (cameraaccepted && vibrateaccepted) {
                Toast.makeText(this, "Permission granted..", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(this, "Permission Denined \n You cannot use app without providing permission", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

输出：在真实设备上运行

现在在真实设备上运行您的应用程序并扫描一些示例二维码，您将开始测试该应用程序。确保在应用程序启动时允许相机权限。

此项目的 GitHub 链接： https://github.com/ChaitanyaMunje/QR_Code_Scanner