图片下载工具类

请求：
@ApiOperation(value = "图片下载", nickname = "图片下载")
@GetMapping("/downImage")
public void downImage(@ApiParam(value = "图片地址", required = true) @RequestParam String imageUrl, HttpServletResponse response) {
    imageExport.imageExport(imageUrl, response);
}

工具类

package com.rk.eai.basic.utils;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Date;


public class imageExport {
    public static void imageExport(String imageUrl, HttpServletResponse response) {
        String fileName = "ITEM_image" + new Date().getTime() + ".png";
        InputStream inputStream = null;
        OutputStream outputStream = null;
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
            //获取图片并获取输入流
            URL url = new URL(imageUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setConnectTimeout(5000);
            inputStream = connection.getInputStream();
            //设置响应头信息
            response.setContentType("image/png,");
            response.setHeader("Content-Disposition", "attachment;" + "filename=" + URLEncoder.encode(fileName, "UTF-8"));
            //获取输出流
            bis = new BufferedInputStream(inputStream);
            outputStream = response.getOutputStream();
            bos = new BufferedOutputStream(outputStream);

            int byteread = 0;
            byte[] bytes = new byte[5 * 1204];
            while ((byteread = bis.read(bytes)) != -1) {
                bos.write(bytes, 0, byteread);
            }
            bos.flush();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭流
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (outputStream != null) {
                try {
                    outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bos != null) {
                try {
                    bos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bis != null) {
                try {
                    bis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}