发送POST请求，包含文件MultipartFile参数，普通字符串参数，请求头参数

/**
     * 使用httpclint 发送文件，如果不传输文件，直接设置fileParams=null，
     * 如果不设置请求头参数，直接设置headerParams=null，就可以进行普通参数的POST请求了
     *
     * @param url          请求路径
     * @param fileParams   文件参数
     * @param otherParams  其他字符串参数
     * @param headerParams 请求头参数
     * @return
     */
    public static String uploadFile(String url, Map<String, MultipartFile> fileParams, Map<String, String> otherParams, Map<String, String> headerParams) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String result = "";
        try {
            HttpPost httpPost = new HttpPost(url);
            //设置请求头
            if (headerParams != null && headerParams.size() > 0) {
                for (Map.Entry<String, String> e : headerParams.entrySet()) {
                    String value = e.getValue();
                    String key = e.getKey();
                    if (StringUtils.isNotBlank(value)) {
                        httpPost.setHeader(key, value);
                    }
                }
            }
            MultipartEntityBuilder builder = MultipartEntityBuilder.create();
            builder.setCharset(Charset.forName("utf-8"));
            builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);//加上此行代码解决返回中文乱码问题
            //    文件传输http请求头(multipart/form-data)
            if (fileParams != null && fileParams.size() > 0) {
                for (Map.Entry<String, MultipartFile> e : fileParams.entrySet()) {
                    String fileParamName = e.getKey();
                    MultipartFile file = e.getValue();
                    if (file != null) {
                        String fileName = file.getOriginalFilename();
                        builder.addBinaryBody(fileParamName, file.getInputStream(), ContentType.MULTIPART_FORM_DATA, fileName);// 文件流
                    }
                }
            }
            //    字节传输http请求头(application/json)
            ContentType contentType = ContentType.create("application/json", Charset.forName("UTF-8"));
            if (otherParams != null && otherParams.size() > 0) {
                for (Map.Entry<String, String> e : otherParams.entrySet()) {
                    String value = e.getValue();
                    if (StringUtils.isNotBlank(value)) {
                        builder.addTextBody(e.getKey(), value, contentType);// 类似浏览器表单提交，对应input的name和value
                    }
                }
            }
            HttpEntity entity = builder.build();
            httpPost.setEntity(entity);
            HttpResponse response = httpClient.execute(httpPost);// 执行提交
            HttpEntity responseEntity = response.getEntity();
            if (responseEntity != null) {
                // 将响应内容转换为字符串
                result = EntityUtils.toString(responseEntity, Charset.forName("UTF-8"));
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                httpClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }