java 获取微信群群二维码 完整代码

获取微信群二维码需要使用微信网页版接口，具体实现代码如下：

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class WeChatQRCode {

    public static void main(String[] args) throws IOException {
        // 微信网页版二维码URL
        String qrCodeUrl = "https://login.wx.qq.com/qrcode/xxxxxxxxxxx";

        // 获取二维码图片
        InputStream in = getInputStream(qrCodeUrl);
        byte[] data = readInputStream(in);

        // 保存二维码图片
        File file = new File("wechat_qrcode.jpg");
        FileOutputStream out = new FileOutputStream(file);
        out.write(data);
        out.close();
    }

    /**
     * 获取输入流
     */
    public static InputStream getInputStream(String urlStr) throws IOException {
        URL url = new URL(urlStr);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        conn.setConnectTimeout(5 * 1000);
        InputStream in = conn.getInputStream();
        return in;
    }

    /**
     * 从输入流中获取字节数组
     */
    public static byte[] readInputStream(InputStream in) throws IOException {
        byte[] buffer = new byte[1024];
        int len = 0;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        while ((len = in.read(buffer)) != -1) {
            out.write(buffer, 0, len);
        }
        in.close();
        byte[] data = out.toByteArray();
        out.close();
        return data;
    }
}

需要将 `qrCodeUrl` 替换为你的微信群二维码URL，注意该URL只有在登录状态下才能获取到。如果没有登录，请先用模拟登录方式获取到登录态。