之前寫過基于html和js的文件上傳方法java 用springMVC 和HttpServletRequest 兩種實現文件上傳的方法和httpClient后臺執行普通post請求的文章java通過httpClient從接口請求數據入庫以及自動生成實體工具類，最近接到一個需求，需要用到后臺去調用遠程服務器的文件上傳接口實現文件上傳，用到了httpClient的MultipartEntityBuilder實現。

maven引入httpClient依賴

org.apache.httpcomponents

httpcore

4.4.13

org.apache.httpcomponents

httpclient

4.5.12

org.apache.httpcomponents

httpmime

4.5.12

以上依賴是筆者成文時maven最新的依賴包。

新建一個UploadFileUtil工具類：

package com.zhaohy.app.utils;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import org.apache.http.HttpEntity;

import org.apache.http.HttpResponse;

import org.apache.http.HttpStatus;

import org.apache.http.client.methods.HttpPost;

import org.apache.http.entity.ContentType;

import org.apache.http.entity.mime.HttpMultipartMode;

import org.apache.http.entity.mime.MultipartEntityBuilder;

import org.apache.http.impl.client.CloseableHttpClient;

import org.apache.http.impl.client.HttpClients;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class UpLoadFileUtil {

private static Logger logger = LoggerFactory.getLogger(UpLoadFileUtil.class);

/**

* 通過httpClient上傳文件

* @param fileName

* @param path

* @return 外部域名的下載url

*/

public static String UploadFileByHttpClient(String fileName,String path, String url) {

String result = "";

CloseableHttpClient httpClient = HttpClients.createDefault();

try {

HttpPost httpPost = new HttpPost(url);

//HttpMultipartMode.RFC6532參數的設定是為避免文件名為中文時亂碼

MultipartEntityBuilder builder = MultipartEntityBuilder.create().setMode(HttpMultipartMode.RFC6532);

httpPost.addHeader("header1", "111");//頭部放文件上傳的head可自定義

File file = new File(path+fileName); //上傳文件的路徑

builder.addBinaryBody("file", file, ContentType.MULTIPART_FORM_DATA, fileName);

builder.addTextBody("params1", "1");//其余參數，可自定義

builder.addTextBody("params2", "2");

HttpEntity entity = builder.build();

httpPost.setEntity(entity);

HttpResponse response = httpClient.execute(httpPost);// 執行提交

HttpEntity responseEntity = response.getEntity();//接收調用外部接口返回的內容

if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){

// 返回的內容都在content中

InputStream content = responseEntity.getContent();

// 定義BufferedReader輸入流來讀取URL的響應

BufferedReader in = new BufferedReader(new InputStreamReader(content));

String line;

while ((line = in.readLine()) != null) {

result += line;

}

if(!AppFrameworkUtil.isBlank(result)) {

logger.info("上傳文件"+fileName+"返回參數==>"+result);

}else {

logger.error("上傳文件失敗：返回result為null");

}

}

}catch(Exception e) {

logger.error("上傳文件失敗：",e);

}finally {//處理結束后關閉httpclient的鏈接

try {

httpClient.close();

} catch (IOException e) {

e.printStackTrace();

}

}

return result;

}

}

上面代碼中 fileName是文件名稱，本地文件路徑，url是遠程上傳接口url,通過httpPost.addHeader來自定義header參數，builder.addTextBody來自定義其他參數，相當于html中form表單中其他的參數，可解析返回來的result拿到自己想拿的信息。