java、 http模拟post上传文件到服务端 模拟form上传文件

需求是这样的：
**1，前后端分离，前端对接pc软件进行文件同步的接口，后的springboot微服务进行文件接收和处理。
2，软件不能直接调用微服务的接口进行上传，只能先走一下前端controller进行转发过来（）。
3，这样就只能用httpclient进行http的转发请求，先把文件上传来放到本地临时处理下，在转到微服务端进行处理。
4，post方式传输，单纯的字符参数好处理，单纯的文件也能处理，2个都存在，会有一些小问题，尤其是报文那里。**

1. 第一步：同步文件的接口

    @ResponseBody
    @RequestMapping(value="/res/upload",method=RequestMethod.POST, produces = "text/html;charset=UTF-8")
    public String softUpload(MultipartHttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
    {
        MultipartFile dataFile = request.getFile("file");
        String userName = request.getParameter("userName");
        String token = request.getParameter("token");
        String fileName = dataFile.getOriginalFilename();
        String ext = fileName.substring(fileName.lastIndexOf("."));
        String saveFileName = "";
        String relativePath = "";
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
        relativePath = sdf.format(new Date()) + File.separator + UUID.randomUUID().toString().replace("-", "");
        saveFileName = Configuration.getDataPath() + "/" + relativePath + ext;
        // 将文件保存起来
        FileUtils.writeByteArrayToFile(new File(saveFileName), dataFile.getBytes());
        String doPost = HttpUtils.doPostWithFile(url, saveFileName,fileName,userName);
        return doPost;
    }

1. 第二部：模拟post传输工具类

/**
     * 提交file模拟form表单
     * @param url
     * @param savefileName
     * @param fileName
     * @param param
     * @return
     */
    public static String doPostWithFile(String url,String savefileName,String fileName, String param) {
        String result = "";
          try {  
                // 换行符  
                final String newLine = "\r\n";  
                final String boundaryPrefix = "--";  
                // 定义数据分隔线  
                String BOUNDARY = "========7d4a6d158c9";  
                // 服务器的域名  
                URL realurl = new URL(url);  
                // 发送POST请求必须设置如下两行
                HttpURLConnection connection = (HttpURLConnection) realurl.openConnection(); 
                connection.setDoOutput(true);
                connection.setDoInput(true);
                connection.setUseCaches(false);
                connection.setRequestMethod("POST");
                connection.setRequestProperty("Connection","Keep-Alive");
                connection.setRequestProperty("Charset","UTF-8");
                connection.setRequestProperty("Content-Type","multipart/form-data; boundary=" + BOUNDARY);
                // 头
                String boundary = BOUNDARY;
                // 传输内容
                StringBuffer contentBody =new StringBuffer("--" + BOUNDARY);
                // 尾
                String endBoundary ="\r\n--" + boundary + "--\r\n";

                // 1. 处理普通表单域(即形如key = value对)的POST请求（这里也可以循环处理多个字段，或直接给json）
                //这里看过其他的资料，都没有尝试成功是因为下面多给了个Content-Type
                //form-data  这个是form上传 可以模拟任何类型
                contentBody.append("\r\n")
                .append("Content-Disposition: form-data; name=\"")
                .append("param" + "\"")
                .append("\r\n")
                .append("\r\n")
                .append(param)
                .append("\r\n")
                .append("--")
                .append(boundary);
                String boundaryMessage1 =contentBody.toString();
                System.out.println(boundaryMessage1);
                out.write(boundaryMessage1.getBytes("utf-8"));

                // 2. 处理file文件的POST请求（多个file可以循环处理）
                contentBody = new StringBuffer();
                contentBody.append("\r\n")
                .append("Content-Disposition:form-data; name=\"")
                .append("file" +"\"; ")   // form中field的名称
                .append("filename=\"")
                .append(fileName +"\"")   //上传文件的文件名，包括目录
                .append("\r\n")
                .append("Content-Type:multipart/form-data")
                .append("\r\n\r\n");
                String boundaryMessage2 = contentBody.toString();
                System.out.println(boundaryMessage2);
                out.write(boundaryMessage2.getBytes("utf-8"));

                // 开始真正向服务器写文件
                File file = new File(savefileName);
                DataInputStream dis= new DataInputStream(new FileInputStream(file));
                int bytes = 0;
                byte[] bufferOut =new byte[(int) file.length()];
                bytes =dis.read(bufferOut);
                out.write(bufferOut,0, bytes);
                dis.close();
                byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();  
                out.write(endData);  
                out.flush();  
                out.close(); 

                // 4. 从服务器获得回答的内容
                String strLine="";
                String strResponse ="";
                InputStream in =connection.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                while((strLine =reader.readLine()) != null)
                {
                        strResponse +=strLine +"\n";
                }
                System.out.print(strResponse);
                return strResponse;
            } catch (Exception e) {  
                System.out.println("发送POST请求出现异常！" + e);  
                e.printStackTrace();  
            }
          return result;
    }

1. 第三部：服务接收端 处理文件file

        //新建资源这个是springboot接口
        @RequestMapping(value = "/upload",method =RequestMethod.POST)
        public ReturnResult<?> uploadRes( MultipartFile file, String param)throws Exception;

        //这里@RequestPart 注解直接接受file就可以了
        public ReturnResult<?> uploadRes(@RequestPart("file") MultipartFile file,@RequestParam("param") String name) throws Exception{
        logger.info("****新建资源****");

        //处理逻辑

        }