java后台调用文件上传接口

借鉴：https://blog.csdn.net/yjclsx/article/details/70675057

/**
     * 调用流程上传文件接口上传文件
     * @param url
     * @param path
     * @return
     */
    public static String sendPostUplodFile(String url,String path) {
        DataOutputStream out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            //打开和URL之间的连接
            HttpURLConnection conn = (HttpURLConnection)realUrl.openConnection();
            //发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            
            String BOUNDARY = "----WebKitFormBoundary07I8UIuBx6LN2KyY";
            conn.setUseCaches(false);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("connection", "Keep-Alive");
//            conn.setRequestProperty("user-agent", "Mozilla/4.0 (conpatible; MSIE 6.0; Windows NT 5.1; SV1)");
            conn.setRequestProperty("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36");
            conn.setRequestProperty("Charsert", "UTF-8");
            conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);
            conn.connect();
            
            out = new DataOutputStream(conn.getOutputStream());
            byte[] end_data = ("
--" + BOUNDARY + "--
").getBytes();
            //添加参数
            StringBuffer sb1 = new StringBuffer();
            sb1.append("--");
            sb1.append(BOUNDARY);
            sb1.append("
");
            sb1.append("Content-Disposition: form-data;name="luid"");
            sb1.append("
");
            sb1.append("
");
            sb1.append("123");
            sb1.append("
");
            out.write(sb1.toString().getBytes());
            //添加参数file
            File file = new File(path);
            StringBuffer sb = new StringBuffer();
            sb.append("--");
            sb.append(BOUNDARY);
            sb.append("
");
            sb.append("Content-Disposition: form-data;name="file";filename="" + file.getName() + """);
            sb.append("
");
            sb.append("Content-Type: application/octet-stream");
            sb.append("
");
            sb.append("
");
            out.write(sb.toString().getBytes());
            
            DataInputStream in1 = new DataInputStream(new FileInputStream(file));
            int bytes = 0;
            byte[] bufferOut = new byte[1024];
            while ((bytes = in1.read(bufferOut)) != -1) {
                out.write(bufferOut,0,bytes);
            }
            out.write("
".getBytes());
            in1.close();
            out.write(end_data);
            
            //flush输出流的缓冲
            out.flush();
            //定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            log.error("发送POST请求出现异常" + e);
            e.printStackTrace();
        }finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (Exception ex) {
                // TODO: handle exception
                ex.printStackTrace();
            }
        }
        return result;
    }

 //将字符串转换json并取值
1 public static String getFileId(String result) {
        JSONObject json = JSONObject.parseObject(result);
        String fileId = "";
        if (result != null) {
            String code = json.getString("errorCode");
            if (code.equals("0000")) {
                fileId = json.getString("fileId");
            }
        }
        
        return fileId;
    }