如何修复此 QR 码扫描仪的代码？

Posted 2023-05-07

【中文标题】如何修复此 QR 码扫描仪的代码？

【英文标题】：How to fix the code this QR Code Scanner?

【发布时间】：2021-09-13 05:47:04

【问题描述】：

我差点在 android Studio 中做了一个用 WebView 扫描二维码的应用，但还没有完成。我的应用程序扫描代码后，该应用程序只是关闭而没有结果。你们能从我的代码中找到问题吗？

这是应用程序的完整代码。

MainActivity.java

package com.example.qr_code_scanner;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.webkit.javascriptInterface;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.Toast;

import com.google.zxing.integration.android.IntentIntegrator;
import com.google.zxing.integration.android.IntentResult;

public class MainActivity extends AppCompatActivity implements View.OnClickListener 

    WebView webView;
    Button scanBtn;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        scanBtn = findViewById(R.id.scanBtn);
        scanBtn.setOnClickListener(this);
    

    @JavascriptInterface
    public void onClick(View v) 
        scanCode();
    

    private void scanCode() 
        IntentIntegrator integrator = new IntentIntegrator(this);
        integrator.setCaptureActivity(CaptureActivity.class);
        //        integrator.setOrientationLocked(false);
        //        integrator.setRequestCode(200)
        integrator.setDesiredBarcodeFormats(IntentIntegrator.ALL_CODE_TYPES);
        integrator.setPrompt("Scanning Code");
        integrator.initiateScan();
        webView.addJavascriptInterface(this, "Android");
    

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) 
        super.onActivityResult(requestCode, resultCode, data);
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if (result != null) 
            if (result.getContents() != null) 
                AlertDialog.Builder builder = new AlertDialog.Builder(this);
                builder.setMessage(result.getContents());
                builder.setTitle("Scanning Result");
                builder.setPositiveButton("Scan Again", new DialogInterface.OnClickListener() 
                    @Override
                    public void onClick(DialogInterface dialog, int which) 
                        scanCode();
                    
                ).setNegativeButton("Finish", new DialogInterface.OnClickListener() 
                    @Override
                    public void onClick(DialogInterface dialog, int which) 
                        finish();
                    
                );
                AlertDialog dialog = builder.create();
                dialog.show();
             else 
                Toast.makeText(this, "No Results", Toast.LENGTH_LONG).show();
            
         else 
            webView.loadUrl(result.getContents());
        
    

CaptureActivity.java

package com.example.qr_code_scanner;

public class CaptureActivity extends com.journeyapps.barcodescanner.CaptureActivity 

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.example.qr_code_scanner">

    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-feature android:name="android.hardware.camera"/>
    <uses-feature android:name="android.hardware.camera.autofocus"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.QR_Code_Scanner">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".CaptureActivity"
            android:screenOrientation="fullSensor"
            android:stateNotNeeded="true"
            android:windowSoftInputMode="stateAlwaysHidden">
        </activity>

    </application>

</manifest>

build.gradle (:app)

plugins 
    id 'com.android.application'


android 
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig 
        applicationId "com.example.qr_code_scanner"
        minSdkVersion 24
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    

    buildTypes 
        release 
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        
    
    compileOptions 
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    


dependencies 

    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'

    implementation 'com.journeyapps:zxing-android-embedded:4.1.0'
    implementation 'androidx.appcompat:appcompat:1.0.2'

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_
    android:layout_
    android:orientation="vertical">

    <LinearLayout
        android:layout_
        android:layout_
        android:orientation="horizontal">

        <Button
            android:id="@+id/scanBtn"
            android:layout_
            android:layout_
            android:text="scan"
            android:padding="4dp"
            android:textSize="20dp"/>
    </LinearLayout>

    <WebView
        android:id="@+id/webview"
        android:layout_
        android:layout_/>

</LinearLayout>

【问题讨论】：

如果您遇到错误，请发布 logcat。仅通过查看代码来找出错误是非常耗时的。

【参考方案1】：

您没有定义您直接调用的 Webview id

webView.addJavascriptInterface(this, "Android");

你错过了这一行

webView = findViewById(R.id.webview);

您正在使用 zxing 的另一件事，您需要在清单中添加一些行，遵循 Zxing Documentation