使用HttpClient MultipartEntityBuilder 上傳文件，並解決中文文件名亂碼問題

遇到一種業務場景，前端上傳的文件需要經過java服務轉發至文件服務。期間遇到了原生HttpClient怎麼使用的問題、怎麼把MultipartFile怎麼重新組裝成Http請求發送出去的問題、文件中文名亂碼問題。最後都解決了，先上代碼，再講遇到的坑

 1 @Slf4j
 2 @Service
 3 public class FileServiceImpl implements IFileService {
 4 
 5     @Value("${FileService.putUrl}")
 6     private String putUrl;
 7     @Value("${FileService.app_id}")
 8     private String appId;
 9     @Value("${FileService.securityKey}")
10     private String secureKey;
11 
12     private final static String UPLOAD_RESPONSE_CODE = "error";
13     private final static Integer UPLOAD_RESPONSE_SUCCESS = 0;
14 
15 
16     @Override
17     public String upload(MultipartFile file) {
18 
19         int timeOut = 30000;
20         CloseableHttpClient httpClient = HttpClientBuilder.create().build();
21         HttpHost proxy = new HttpHost("127.0.0.1", 62145, "http"); //設置本地fiddler代理，方便排查問題
22         RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(timeOut)
23                 .setConnectTimeout(timeOut).setSocketTimeout(timeOut).setProxy(proxy).build();
24         HttpPost httpPost = new HttpPost(putUrl);
25         httpPost.setConfig(requestConfig);
26         try {
27             //BROWSER_COMPATIBLE自定義charset，RFC6532=utf-8，STRICT=iso-8859-1
28             //此處一定要用RFC6532，網上普遍用的BROWSER_COMPATIBLE依然會出現中文名亂碼
29             MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create().setMode(HttpMultipartMode.RFC6532);
30             //multipartEntityBuilder.setCharset(Charset.forName("UTF-8")); //此處踩坑，轉發出去的filename依然為亂碼
31            //ContentType contentType = ContentType.create("multipart/form-data",Charset.forName("UTF-8")); //此處也是坑，轉發出去的filename依然為亂碼
32             multipartEntityBuilder.addBinaryBody("file", file.getInputStream(), ContentType.DEFAULT_BINARY, file.getOriginalFilename());
33 
34             multipartEntityBuilder.addTextBody("app_id", appId); //可替換成你自己需要的附加欄位
35             long time = System.currentTimeMillis() / 1000;
36             multipartEntityBuilder.addTextBody("time", String.valueOf(time)); //可替換成你自己需要的附加欄位
37             String beforeSign = String.format("app_id=%s&time=%s%s", appId, time, secureKey);
38             String sign = MD5Util.md5(beforeSign);
39             multipartEntityBuilder.addTextBody("sign", sign); //可替換成你自己需要的附加欄位
40 
41             HttpEntity requestEntity = multipartEntityBuilder.build();
42             httpPost.setEntity(requestEntity);
43             HttpResponse httpResponse = httpClient.execute(httpPost);
44             int statusCode= httpResponse.getStatusLine().getStatusCode();
45             if (statusCode != 200) throw new BizException(BizCode.INNER_SERVICE_ERROR, "響應狀態碼為：" + statusCode);
46             HttpEntity responseEntity = httpResponse.getEntity();
47             return getUrlString(EntityUtils.toString(responseEntity));
48         } catch (Exception e) {
49             log.error("發送文件異常：{}", e);
50             throw new BizException(BizCode.INNER_SERVICE_ERROR, "發送文件服務異常:" + e.getMessage());
51         } finally {
52             try {
53                 httpClient.close();
54             } catch (IOException e) {
55                 log.error("關閉httpClient異常：" + e.getMessage(), e);
56             }
57         }
58     }
59 
60     private String getUrlString(String jsonString) {
61         try{
62             log.debug("解析json串："+ jsonString);
63             JSONObject jsonObject = JSONObject.parseObject(jsonString);
64             if (jsonObject.getInteger(UPLOAD_RESPONSE_CODE) != UPLOAD_RESPONSE_SUCCESS) {
65                 log.error("文件服務返回錯誤：" + jsonObject.getString("data"));
66                 throw new OtherServiceReturnErrorException("文件服務返回錯誤：" + jsonObject.getString("data"));
67             }
68             return ((JSONObject)jsonObject.get("data")).get("original").toString();
69         }catch (Exception e) {
70             log.error("文件服務返回json解析錯誤：" + jsonString);
71             throw new OtherServiceReturnErrorException("文件服務返回json解析錯誤：" + jsonString);
72         }
73 
74     }
75 }

特別說明及遇到的坑：

1. 這裡基於tomcat進行請求轉發，需要在代碼中手動添加代理：

HttpHost proxy = new HttpHost("127.0.0.1", 62145, "http"); //設置本地fiddler代理，方便排查問題
RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(timeOut)
        .setConnectTimeout(timeOut).setSocketTimeout(timeOut).setProxy(proxy).build();

2. MultipartFile通過getInputStream()可以將流設置到MultipartEntityBuilder中，其中addBinaryBody裡面的ContentType 和 filename必須設置，要不然後續服務讀取不到這個文件流

MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create().setMode(HttpMultipartMode.RFC6532);
multipartEntityBuilder.addBinaryBody("file", file.getInputStream(), ContentType.DEFAULT_BINARY, file.getOriginalFilename());

3. file.getOriginalFilename()方法雖然沒有亂碼，但是addBinaryBody後，組裝的Http請求出去總是亂碼，如下圖：

踩了各種坑，如為MultipartEntityBuilder設置Charset或者是手動設置ContentType，都無法解決此問題，文件名依然是上圖所示亂碼

後來發現在MultipartEntityBuilder中設置Mode為HttpMultipartMode.RFC6532可以完美解決這個問題，並且不再需要單獨設置ContentType或Charset，因為HttpMultipartMode.RFC6532就告訴了MultipartEntityBuilder，裡面的數據都要使用UTF-8進行處理，fiddler抓到的請求發現filename成功變成中文名。

done