// ==================== 文件：MainActivity.java ====================
package com.example.qrcodegenerator;
 
import androidx.appcompat.app.AppCompatActivity;
 
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
 
import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
 
/**
 * 主页面：输入 URL 并生成二维码
 */
public class MainActivity extends AppCompatActivity {
 
    private EditText editTextUrl;
    private Button buttonGenerate;
    private ImageView imageViewQRCode;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        editTextUrl = findViewById(R.id.editTextUrl);
        buttonGenerate = findViewById(R.id.buttonGenerate);
        imageViewQRCode = findViewById(R.id.imageViewQRCode);
 
        // 点击按钮生成二维码
        buttonGenerate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String url = editTextUrl.getText().toString().trim();
                if (url.isEmpty()) {
                    Toast.makeText(MainActivity.this, "请输入 URL", Toast.LENGTH_SHORT).show();
                } else {
                    Bitmap qrCodeBitmap = generateQRCode(url, 500, 500);
                    if (qrCodeBitmap != null) {
                        imageViewQRCode.setImageBitmap(qrCodeBitmap);
                    } else {
                        Toast.makeText(MainActivity.this, "二维码生成失败", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });
    }
 
    /**
     * 生成二维码
     *
     * @param text 需要编码的内容（URL 或字符串）
     * @param width 宽度
     * @param height 高度
     * @return Bitmap 二维码图像
     */
    private Bitmap generateQRCode(String text, int width, int height) {
        QRCodeWriter writer = new QRCodeWriter();
        try {
            // 生成 BitMatrix
            BitMatrix bitMatrix = writer.encode(text, BarcodeFormat.QR_CODE, width, height);
 
            // 创建 Bitmap
            Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
 
            // 遍历 BitMatrix，将二维码点绘制到 Bitmap
            for (int x = 0; x < width; x++) {
                for (int y = 0; y < height; y++) {
                    bitmap.setPixel(x, y, bitMatrix.get(x, y) ? 0xFF000000 : 0xFFFFFFFF);
                }
            }
 
            return bitmap;
        } catch (WriterException e) {
            e.printStackTrace();
        }
        return null;
    }
}
 
 
// ==================== 文件：activity_main.xml ====================
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dp"
    android:gravity="center">
 
    <!-- 输入 URL -->
    <EditText
        android:id="@+id/editTextUrl"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入 URL"
        android:inputType="textUri"
        android:padding="10dp"/>
 
    <!-- 生成二维码按钮 -->
    <Button
        android:id="@+id/buttonGenerate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="生成二维码"
        android:layout_marginTop="20dp"/>
 
    <!-- 显示二维码 -->
    <ImageView
        android:id="@+id/imageViewQRCode"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_marginTop="30dp"
        android:background="#CCCCCC"/>
</LinearLayout>
 
 
// ==================== 文件：build.gradle（app） ====================
dependencies {
    implementation 'com.google.zxing:core:3.5.1'
}