生成二維碼工具類（已在多個生產系統使用）

content可以是一個url ，返回的是一個字節數組，之後可以把字節數組寫到某一個圖片文件中，也可以上傳到oss或者七牛。

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

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Hashtable;


public class QRCodeUtil {

    public static final int BLACK = 0xFF000000;
    public static final int WHITE = 0xFFFFFFFF;

    public static byte[] getByte(String content) throws WriterException, IOException {
        Hashtable<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();
        hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
        hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
        hints.put(EncodeHintType.MARGIN, 1);
        BitMatrix bitMatrix = new MultiFormatWriter().encode(content,
                BarcodeFormat.QR_CODE, 300, 300, hints);
        //調用去除白邊方法
        bitMatrix = deleteWhite(bitMatrix);
        int width = bitMatrix.getWidth();
        int height = bitMatrix.getHeight();
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                image.setRGB(x, y, bitMatrix.get(x, y) ? BLACK
                        : WHITE);
            }
        }
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ImageIO.write(image, "png", outputStream);
        return outputStream.toByteArray();
    }

    private static BitMatrix deleteWhite(BitMatrix matrix) {
        int[] rec = matrix.getEnclosingRectangle();
        int resWidth = rec[2] + 1;
        int resHeight = rec[3] + 1;
        BitMatrix resMatrix = new BitMatrix(resWidth, resHeight);
        resMatrix.clear();
        for (int i = 0; i < resWidth; i++) {
            for (int j = 0; j < resHeight; j++) {
                if (matrix.get(i + rec[0], j + rec[1]))
                    resMatrix.set(i, j);
            }
        }
        return resMatrix;
    }
}