转换为base64格式

package com.hxh.basic.project.Test02;

import com.alibaba.fastjson.JSON;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;

import java.io.ByteArrayOutputStream;
import java.util.Hashtable;

public class Test {
    public static void main(String[] args) {
        String str = "123456";
        getQRCodeImage(str);
    }

    /**
     * QR_CODE_DEFAULT_WIDTH 二维码默认宽
     */
    private static final int QR_CODE_DEFAULT_WIDTH = 320;

    /**
     * QR_CODE_DEFAULT_CHARSET 二维码默认的字符集
     */
    private static final String QR_CODE_DEFAULT_CHARSET = "utf-8";

    /**
     * 生成二维码，返回字节流
     *
     * @param inputString
     * @return String
     */
    public static String getQRCodeImage(String inputString) {
        System.out.println(String.format("UserServiceImpl.getQRCodeImage request inputString=%s", inputString));

        String result = "";
        try {
            QRCodeWriter qrCodeWriter = new QRCodeWriter();
            Hashtable hints = new Hashtable();
            hints.put(EncodeHintType.CHARACTER_SET, QR_CODE_DEFAULT_CHARSET);
            BitMatrix bitMatrix = qrCodeWriter.encode(inputString, BarcodeFormat.QR_CODE, QR_CODE_DEFAULT_WIDTH, QR_CODE_DEFAULT_WIDTH, hints);
            bitMatrix = deleteWhite(bitMatrix);
            ByteArrayOutputStream pngOutputStream = new ByteArrayOutputStream();
            MatrixToImageWriter.writeToStream(bitMatrix, "png", pngOutputStream);
            result = "data:image/png;base64," + Base64.encode(pngOutputStream.toByteArray());
            System.out.println(String.format("base64 res=%s", result));
        } catch (Exception e) {
            System.out.println(String.format("UserServiceImpl.getQRCodeImage exception! 错误信息=%s", e));
            System.out.println(String.format("com.jd.crm.gateway.service.user.impl.UserServiceImpl.getQRCodeImage(java.lang.String)：result=%s", JSON.toJSON(result)));
            return "错误";
        }
        return result;
    }

    /**
     * 二维码方法封装
     *
     * @param matrix
     * @return BitMatrix
     */
    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;
    }
}

// TODO 输出：UserServiceImpl.getQRCodeImage request inputString=123456
// TODO 输出：base64 res=data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAOgAAADoAQAAAADN0pXVAAABEklEQVR42u3ZsRGDMAwFUHEUKRmBUTIaHo1RGIEyBYeCJDu2ORJjp/1qkuO5UhR/A0ShHmyfHc/hUkfQCh1Zaz503GhaO/mqtULrdLPmisaFR03QZpUaoP+rH1NoqyZj2rOzPl/tDNCCJnkUdtHrtIL+Vk5qsWSPBa1QGVNetc+82MTyi/xCaIVKO92w09M666TPppP/FaD3VHZRUe2zT3Yivw1AK5T5SHbrsw4v73Yz1EvLoRX6OWKSjanfBtJkh97SPH2ibudkhxY0OSPJJVHZUJf+fNqEljR9vpHkkYY8tEqz5xsu5pE9c4M2qDY36TO0WTXkOdxL2mkTel+z/344I426EFqj+buJ78kOLSj/qjdgrUGR/YlwbwAAAABJRU5ErkJggg==