本文是上一篇文章Golang+Android（使用HttpURLConnection）实现文件上传的升级版，实现多文件上传功能，并且附带http请求参数。
客户端代码：
/*** 使用HttpURLConnection通过POST方式提交请求，并上传文件。** @param actionUrl 访问的url* @param textParams 文本类型的POST参数(key:value)* @param filePaths 文件路径的集合* @return 服务器返回的数据，，出现异常时返回 null*/public static String postWithFiles(String actionUrl, Map<String, String> textParams, List<String> filePaths) {try {final String BOUNDARY = UUID.randomUUID().toString();final String PREFIX = "–";final String LINE_END = "\r\n";final String MULTIPART_FROM_DATA = "multipart/form-data";final String CHARSET = "UTF-8";URL uri = new URL(actionUrl);HttpURLConnection conn = (HttpURLConnection) uri.openConnection();//缓存大小conn.setChunkedStreamingMode(1024 * 64);//超时conn.setReadTimeout(5 * 1000);conn.setDoInput(true);conn.setDoOutput(true);conn.setUseCaches(false);conn.setRequestMethod("POST");conn.setRequestProperty("connection", "keep-alive");conn.setRequestProperty("Charset", "UTF-8");conn.setRequestProperty("Content-Type", MULTIPART_FROM_DATA + ";boundary=" + BOUNDARY);// 拼接文本类型的参数StringBuilder textSb = new StringBuilder();if (textParams != null) {for (Map.Entry<String, String> entry : textParams.entrySet()) {textSb.append(PREFIX).append(BOUNDARY).append(LINE_END);textSb.append("Content-Disposition: form-data; name=\&;" + entry.getKey() + "\&;" + LINE_END);textSb.append("Content-Type: text/plain; charset=" + CHARSET + LINE_END);textSb.append("Content-Transfer-Encoding: 8bit" + LINE_END);textSb.append(LINE_END);textSb.append(entry.getValue());textSb.append(LINE_END);}}DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());outStream.write(textSb.toString().getBytes());//参数POST方式//outStream.write("userId=1&cityId=26".getBytes());// 发送文件数据if (filePaths != null) {for (String file : filePaths) {StringBuilder fileSb = new StringBuilder();fileSb.append(PREFIX).append(BOUNDARY).append(LINE_END);fileSb.append("Content-Disposition: form-data; name=\&;file\&;; filename=\&;" +file.substring(file.lastIndexOf("/") + 1) + "\&;" + LINE_END);fileSb.append("Content-Type: application/octet-stream; charset=" + CHARSET + LINE_END);fileSb.append(LINE_END);outStream.write(fileSb.toString().getBytes());InputStream is = new FileInputStream(file);byte[] buffer = new byte[1024 * 8];int len;while ((len = is.read(buffer)) != -1) {outStream.write(buffer, 0, len);}is.close();outStream.write(LINE_END.getBytes());}}// 请求结束标志outStream.write((PREFIX + BOUNDARY + PREFIX + LINE_END).getBytes());outStream.flush();// 得到响应码int responseCode = conn.getResponseCode();BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(), CHARSET));StringBuilder resultSb = null;String line;if (responseCode == 200) {resultSb = new StringBuilder();while ((line = br.readLine()) != null) {resultSb.append(line).append("\n");}}br.close();outStream.close();conn.disconnect();return resultSb == null ? null : resultSb.toString();} catch (IOException e) {e.printStackTrace();}return null;}服务器端代码：//客户端上传多个文件,并带有请求参数func handleUploadFile(w http.ResponseWriter, r *http.Request) {fmt.Println("client:", r.RemoteAddr, "method:", r.Method)r.ParseForm()r.ParseMultipartForm(32 << 20) //最大内存为32M//读取参数userId := r.FormValue("userId")cityId := r.FormValue("cityId")log.Println("userId=", userId, "cityId=", cityId)mp := r.MultipartFormif mp == nil {log.Println("not MultipartForm.")w.Write(([]byte)("不是MultipartForm格式"))return}fileHeaders, findFile := mp.File["file"]if !findFile || len(fileHeaders) == 0 {log.Println("file count == 0.")w.Write(([]byte)("没有上传文件"))return}for _, v := range fileHeaders {fileName := v.Filenamefile, err := v.Open()checkErrorV2(err, "Open file error."+fileName)defer file.Close()outputFilePath := "/home/admin/桌面/" + fileNamewriter, err := os.OpenFile(outputFilePath, os.O_WRONLY|os.O_CREATE, 0666)checkErrorV2(err, "Open local file error")io.Copy(writer, file)}msg := fmt.Sprintf("成功上传了%d个文件", len(fileHeaders))w.Write(([]byte)(msg))}注：checkErrorV2是一个简单的检查错误的函数。
与其用泪水悔恨今天，不如用汗水拼搏今天。
