二维码---生成并下载二维码

package com.epalmpay.util;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import org.apache.commons.io.output.ByteArrayOutputStream;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by wucongpeng on 2017/6/11.
 */
public class DownLoadUtil {

    /**
     * 生成并下载二维码
     * @param url 二维码对于URL
     * @param width 二维码宽
     * @param height 二维码高
     * @param format  二维码格式
     * @return
     * @throws WriterException
     * @throws IOException
     */
    public static ResponseEntity<byte[]> getResponseEntity(String url, String fileName, int width, int height, String format) throws WriterException, IOException {

//        String fileName = url.substring(url.lastIndexOf('/') + 1);

        Map<EncodeHintType, Object> hints = new HashMap<EncodeHintType, Object>();
        hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
        BitMatrix bitMatrix = new MultiFormatWriter().encode(url,
                BarcodeFormat.QR_CODE, width, height, hints);// 生成矩阵
        //将矩阵转为Image
        BufferedImage image = MatrixToImageWriter.toBufferedImage(bitMatrix);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        ImageIO.write(image, format, out);//将BufferedImage转成out输出流
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        headers.setContentDispositionFormData("attachment", new String(fileName.getBytes("utf-8"), "ISO8859-1"));
        return new ResponseEntity<byte[]>(out.toByteArray(),
                headers, HttpStatus.CREATED);
    }
}