通过后台Http请求的形式实现文件的上传与传输

本文仅已两个不同的接口来模拟两台服务器（两台服务器是同样的代码即可实现）

本文是比较简单的实现【初级版】，能够满足文件的发送，并且能够携带必要的参数
后续会迭代新的版本，比如说多文件传输，参数多样化等

/**
 * 模拟发送方
 */
@RequestMapping(value = "/send")
@ResponseBody
public void send() throws IOException {
    String requestUrl = "http://127.0.0.1/profile/filetest/rec";
    Map<String, String> params = new HashMap<>();
    File file = new File("D:\\test\\test.png");
    HttpFileUtils.upLoadFilePost(requestUrl, file, params);
}

/**
 * 模拟接收方
 */
@RequestMapping(value = "/rec")
@ResponseBody
public String rec(MultipartHttpServletRequest multiRequest){
    if (multiRequest == null)
        return null;
    try {
        MultipartFile file = multiRequest.getFile("file");
        if (!file.isEmpty()) {
            Map<String, String[]> parameterMap = multiRequest.getParameterMap();
            //接收参数信息
            for(String key: parameterMap.keySet()){
                System.err.println(key+":"+parameterMap.get(key));
            }

            //接收文件
            String profilePath = "D:\\test\\1\\rec.png";
            File iFile = new File(profilePath);
            File iFileParent = iFile.getParentFile();
            if (!iFileParent.exists())
                iFileParent.mkdirs();
            // 转存文件
            file.transferTo(iFile);
        }
    } catch (Exception e1) {
        e1.printStackTrace();
        logger.info("从Request拉取文件失败");
    }
    return "success";
}

工具类

/**
 * 通用http发送文件方法
 *
 * @author liguangni
 * @Date 2022.03.18
 */
public class HttpFileUtils {
    private static final Logger log = LoggerFactory.getLogger(HttpFileUtils.class);


    /**
     * 通过Http发送单个文件
     *
     * @param requestUrl 目标接口请求地址
     * @param file      发送的文件
     * @param params    附加的参数
     * @return
     * @throws IOException
     */
    public static String upLoadFilePost(String requestUrl, File file, Map<String, String> params) throws IOException {
        String BOUNDARY = java.util.UUID.randomUUID().toString();
        String PREFIX = "--", LINEND = "\r\n";
        String MULTIPART_FROM_DATA = "multipart/form-data";
        String CHARSET = "UTF-8";
        URL uri = new URL(requestUrl);
        HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
        conn.setReadTimeout(5 * 1000);
        conn.setDoInput(true);// 允许输入
        conn.setDoOutput(true);// 允许输出
        conn.setUseCaches(false);
        conn.setRequestMethod("POST"); // Post方式
        conn.setRequestProperty("connection", "keep-alive");
        conn.setRequestProperty("Charsert", "UTF-8");
        conn.setRequestProperty("Content-Type", MULTIPART_FROM_DATA + ";boundary=" + BOUNDARY);

        DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());

        // 添加参数
        StringBuffer paramsb = new StringBuffer();
        for (Map.Entry<String, String> entry : params.entrySet()) {
            paramsb.append(PREFIX);
            paramsb.append(BOUNDARY);
            paramsb.append(LINEND);
            paramsb.append("Content-Disposition: form-data;name=\"" + entry.getKey() + "\"");
            paramsb.append(LINEND);
            paramsb.append(LINEND);
            paramsb.append(entry.getValue());
            paramsb.append(LINEND);
        }
        outStream.write(paramsb.toString().getBytes());

        // 发送文件数据
        StringBuilder sb1 = new StringBuilder();
        sb1.append(PREFIX);
        sb1.append(BOUNDARY);
        sb1.append(LINEND);
        sb1.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + file.getName() + "\"" + LINEND);
        sb1.append("Content-Type: application/octet-stream; charset=" + CHARSET + LINEND);
        sb1.append(LINEND);
        outStream.write(sb1.toString().getBytes());
        InputStream is = new FileInputStream(file);
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = is.read(buffer)) != -1) {
            outStream.write(buffer, 0, len);
        }

        is.close();
        outStream.write(LINEND.getBytes());


        // 请求结束标志
        byte[] end_data = (PREFIX + BOUNDARY + PREFIX + LINEND).getBytes();
        outStream.write(end_data);
        outStream.flush();

        // 得到响应码
        int res = conn.getResponseCode();
        if (res == 200) {
            InputStream in = conn.getInputStream();
            InputStreamReader isReader = new InputStreamReader(in);
            BufferedReader bufReader = new BufferedReader(isReader);
            String line = "";
            String data = "";
            while ((line = bufReader.readLine()) != null) {
                data += line;
            }
            outStream.close();
            conn.disconnect();
            return data;
        }
        outStream.close();
        conn.disconnect();
        return null;
    }
}