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

org.apache.httpcomponents

httpclient

4.4

org.apache.httpcomponents

httpmime

4.4

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> resultview = new resultview<>();

list 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：