适用场景：
网络绝对路径的URL文件或图片，不存储到本地，转换成stream,直接使用HTTPClient传送到SpringBoot的服务端，将文件存储下来，并返回一个文件地址。目前分层架构的系统越来越多这种需求，所以记录下来以备不时之需。
1、调用端
首先引入httpclient所需包
<dependency> ???????<groupId>org.apache.httpcomponents</groupId> ???????<artifactId>httpclient</artifactId> ???????<version>4.4</version> ???</dependency> ???<dependency> ???????<groupId>org.apache.httpcomponents</groupId> ???????<artifactId>httpmime</artifactId> ???????<version>4.4</version> ???</dependency>
调用代码：
package test.http;import com.alibaba.fastjson.JSON;import com.alibaba.fastjson.JSONArray;import com.alibaba.fastjson.JSONObject;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.methods.HttpPost;import org.apache.http.entity.ContentType;import org.apache.http.entity.mime.MultipartEntityBuilder;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.util.EntityUtils;import java.io.*;import java.net.URL;import java.nio.charset.Charset;/** * 文件传送 * 发送文件流到服务器端 * 服务器端使用SpringBoot的MultipartFile接收 * * 适用场景： * 绝对路径的URL文件，不存储到本地，转换成stream,直接使用HTTPClient传送到SpringBoot * */public class TestUpload { ???public static void main(String[] args) { ???????//文件URL，此处取豆瓣上的一个图片 ???????String fileUrl ="https://img1.doubanio.com/view/photo/l/public/p2537149328.webp"; ???????try { ???????????//提取到文件名 ???????????String fileName = fileUrl.substring(fileUrl.lastIndexOf("/")+1); ???????????//转换成文件流 ???????????InputStream is = new URL(fileUrl).openStream(); ???????????//接收文件的服务器地址 ???????????String uploadURL = "http://localhost:8003/fileupload"; ???????????//创建HttpClient ???????????CloseableHttpClient httpClient = HttpClients.createDefault(); ???????????HttpPost httpPost = new HttpPost(uploadURL); ???????????MultipartEntityBuilder builder = MultipartEntityBuilder.create(); ???????????/*绑定文件参数，传入文件流和contenttype，此处也可以继续添加其他formdata参数*/ ???????????builder.addBinaryBody("file",is, ContentType.MULTIPART_FORM_DATA,fileName); ???????????HttpEntity entity = builder.build(); ???????????httpPost.setEntity(entity); ???????????//执行提交 ???????????HttpResponse response = httpClient.execute(httpPost); ???????????HttpEntity responseEntity = response.getEntity(); ???????????if(responseEntity != null){ ???????????????//将响应的内容转换成字符串 ???????????????String result = EntityUtils.toString(responseEntity, Charset.forName("UTF-8")); ???????????????//此处根据服务器返回的参数转换，这里返回的是JSON格式 ???????????????JSONObject output = JSON.parseObject(result); ???????????????JSONArray body = output.getJSONArray("body"); ???????????????String resUrl = body.get(0)+""; ???????????????System.out.println(resUrl); ???????????} ???????}catch (Exception ex){ ???????????ex.printStackTrace(); ???????} ???}}2、服务端
服务端直接使用MultipartFile接收即可
/** ????* 上传文件 ????* ?????* @throws BusinessException ????*/ ???@PostMapping("") ???public String upload(@RequestParam(defaultValue = "", required = false) String prefix, ???????????@RequestParam("file") MultipartFile... files) throws BusinessException { ???????ResultView<List<String>> resultView = new ResultView<>(); ???????List<String> list = new ArrayList<>(); ???????for (MultipartFile file : files) { ???????????if (file.isEmpty()) { ???????????????log.warn("have empty upload file,you need check is right?"); ???????????????continue; ???????????} ???????????String filepath = storageService.store(file, prefix); ???????????list.add(fileServerAddress + filepath.replaceAll("\\\\", "/")); ???????} ???????resultView.setBody(list); ???????log.info(JSONObject.toJSONString(resultView)); ???????return JSONObject.toJSONString(resultView); ???}具体如何存储如何返回，因人而异，我这里返回的是JSON字符串。
其他：本文参考了博友Vincent-Li的博文，表示感谢：
https://www.cnblogs.com/lyxy/p/5629151.html
使用HttpClient发送文件流到服务器端
原文地址：https://www.cnblogs.com/tobeymarshall/p/10215101.html