Android - 生成二维码

集成开发环境：

Android Studio 4.1.1
Build #AI-201.8743.12.41.6953283, built on November 5, 2020
Runtime version: 1.8.0_242-release-1644-b01 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Windows 10 10.0

生成二维码图片

新建项目，选择 Empty Activity，在配置项目时，我选择的 Minimum SDK 是 API 16: Android 4.1 (Jelly Bean)

编辑 app\build.gradle 文件，引入依赖（第 40 行）：

plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example"
        minSdkVersion 16
        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:1.1.0'
    implementation 'com.google.android.material:material:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    implementation 'com.google.zxing:core:3.3.0'
}

编辑 src\main\res\layout\activity_main.xml 文件，删除原有的 TextView 元素，添加 ImageView 元素：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:layout_marginBottom="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

编辑 MainActivity：

package com.example;

import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

import java.util.Hashtable;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
    
    

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

        initView();
    }
    
    private void initView() {
    
    
        imageView = (ImageView) findViewById(R.id.imageView);

        try {
    
    
            String contents = "生成 1 张二维码（QR Code）图片";

            Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
            hints.put(EncodeHintType.MARGIN, 1);

            Bitmap bitmap = createQrCode(contents, 800, 800, hints);

            imageView.setImageBitmap(bitmap);
        } catch (WriterException e) {
    
    
            e.printStackTrace();
            Log.e("MainActivity", e.getMessage());
        }
    }
    
    public Bitmap createQrCode(String contents, int width, int height, Map<EncodeHintType, Object> hints) throws WriterException {
    
    
        if (contents == null || contents.trim().equals(""))
            return null;
        else if (width < 0 || height < 0)
            return null;

        BitMatrix bitMatrix = new QRCodeWriter().encode(contents, BarcodeFormat.QR_CODE, width, height, hints);

        int[] pixels = new int[width * height];
        for (int y = 0; y < height; y++) {
    
    
            for (int x = 0; x < width; x++)
                pixels[y * width + x] = bitMatrix.get(x, y) ? Color.BLACK : Color.WHITE;
        }

        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);
        bitmap.setPixels(pixels, 0, width, 0, 0, width, height);

        return bitmap;
    }
}

效果

参考

Android生成自定义二维码