springboot进行httpclient接口请求,请求带文件MultipartFile和普通数据类型的解决方案

场景:
文件服务器的接口如下

@ApiResponses({ @ApiResponse(code = 200, message = "文件上传成功"), @ApiResponse(code = 120, message = "文件上传失败") })
@RequestMapping(value = "/upload", method = RequestMethod.POST)
public ResultData fileUpload(@ApiParam(value = "上传的文件", required = true)  MultipartFile uploadFile, String sig) {
			......省略
}

如上图,上传文件接口需要两个参数,uploadFile文件类型参数和sig普通数据类型参数。这就涉及到了HTTP基础，HTTP请求分为了消息头和消息体，头信息里面的Content-Type字段定义了消息体的请求格式，SpringMvc是按照请求头来解析消息内容的。
文件的请求头必须是multipart/form-data，而普通数据类型这里定为application/json。怎么兼容呢，这里提供一个解决思路：

构造两个ContentType,文件用文件流传输,请求头为multipart/form-data；
普通数据类型用字节流传输,请求头为application/json；
构造完放入放入一个httpEntity实例中发起请求

代码如下：

 @RequestMapping(value="/img/upload",method = RequestMethod.POST)
 public ResultObject imgUpload(@ApiParam(value="上传的文件",required=true) MultipartFile uploadFile) throws Exception {
 	    if(uploadFile == null ) {
 		   logger.error(ResponseCode.UPLOAD_NULL_EXCEPTION.msg);
 		   return ResultUtils.error(ResponseCode.UPLOAD_NULL_EXCEPTION);
 	    }

		if (uploadFile.getSize() >= Integer.valueOf(maxImg)*1024*1024) {
			logger.error(ResponseCode.UPLOAD_OVER_LIMIT_EXCEPTION.msg);
			return ResultUtils.error(ResponseCode.UPLOAD_OVER_LIMIT_EXCEPTION);
		｝
		
		if (uploadFile.getSize() < Integer.valueOf(1024)) ｛
			logger.error(ResponseCode.DELETE_LOW_LIMIT_EXCEPTION.msg);
			return ResultUtils.error(ResponseCode.DELETE_LOW_LIMIT_EXCEPTION);
		｝

		String requestUrl = host + ":" + port + "/file/upload";
		Map resultMap = new HashMap();
		CloseableHttpClient httpClient = HttpClients.createDefault();
		String result = "";
				try {
					HttpPost httpPost = new HttpPost(requestUrl);
					MultipartEntityBuilder builder = MultipartEntityBuilder.create();
					builder.setCharset(java.nio.charset.Charset.forName("UTF-8"));
					builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
					//	文件传输http请求头(multipart/form-data)
					builder.addBinaryBody("uploadFile", uploadFile.getInputStream(), ContentType.MULTIPART_FORM_DATA,
							uploadFile.getOriginalFilename());// 文件流
					//	字节传输http请求头(application/json)
					ContentType contentType = ContentType.create("application/json", Charset.forName("UTF-8"));
					builder.addTextBody("sig", sig, contentType);//字节流

					HttpEntity entity = builder.build();
					httpPost.setEntity(entity);
					HttpResponse response = httpClient.execute(httpPost);
					// 执行提交
					HttpEntity responseEntity = response.getEntity();
					resultMap.put("scode", String.valueOf(response.getStatusLine().getStatusCode()));
					resultMap.put("data", "");
					if (responseEntity != null) {
						// 将响应内容转换为字符串
						result = EntityUtils.toString(responseEntity, java.nio.charset.Charset.forName("UTF-8"));
						resultMap.put("data", result);
					}
					JSONObject jsonObj = JSONObject.parseObject(result);
					if (jsonObj.getString("code").equals("0")) {
						return ResultUtils.success(jsonObj.getString("data"),ResponseCode.OK);
					} else {
						return ResultUtils.error(jsonObj.getString("msg"),ResponseCode.UPLOAD_FILE_FAIL_EXCEPTION);
					｝
				} catch (Exception e) {
					resultMap.put("scode", "error");
					resultMap.put("data", "HTTP请求出现异常: " + e.getMessage());
					resultMap.put("msg", "HTTP请求出现异常:连接到文件服务器失败 ");

					Writer w = new StringWriter();
					e.printStackTrace(new PrintWriter(w));
					return ResultUtils.error(resultMap.get("msg"),ResponseCode.FAIL);
				} finally {
					try {
						httpClient.close();
						} catch (IOException e) {
						e.printStackTrace();
					}
				}
			}

所需maven依赖


	com.alibaba
	fastjson		
	1.2.8



     org.apache.httpcomponents
     httpcore
     4.4.10
 
 

     org.apache.httpcomponents
     httpclient
     4.5.6