上传文件实现方法

public static String formUpload(String urlStr, Map<String, String> textMap, Map<String, String> fileMap, String uri) {   String res = "";   HttpURLConnection conn = null;   String BOUNDARY = "---------------------------123821742118716"; // boundary就是request头和上传文件内容的分隔符   try {      URL url = new URL(urlStr);      conn = (HttpURLConnection) url.openConnection();      conn.setConnectTimeout(5000);      conn.setReadTimeout(30000);      conn.setDoOutput(true);      conn.setDoInput(true);      conn.setUseCaches(false);      conn.setRequestMethod("POST");      conn.setRequestProperty("Connection", "Keep-Alive");      conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");      conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);

OutputStream out = new DataOutputStream(conn.getOutputStream());      // text      if (textMap != null) {         StringBuilder strBuilder = new StringBuilder();         for (Object o : textMap.entrySet()) {            Map.Entry entry = (Map.Entry) o;            String inputName = (String) entry.getKey();            String inputValue = (String) entry.getValue();            if (inputValue == null) {               continue;            }            strBuilder.append("\r\n").append("--").append(BOUNDARY).append("\r\n");            strBuilder.append("Content-Disposition: form-data; name=\"").append(inputName).append("\"\r\n\r\n");            strBuilder.append(inputValue);         }         out.write(strBuilder.toString().getBytes());      }

// file      if (fileMap != null) {         for (Object o : fileMap.entrySet()) {            Map.Entry entry = (Map.Entry) o;            String inputName = (String) entry.getKey();            String inputValue = (String) entry.getValue();            if (inputValue == null) {               continue;            }

InputStream inputStream = new URL(uri).openStream();            File file = new File(inputValue);            String filename = file.getName();            String contentType = new MimetypesFileTypeMap().getContentType(file);            if (filename.endsWith(".png")) {               contentType = "image/png";            }            if (contentType == null || contentType.equals("")) {               contentType = "application/octet-stream";            }

StringBuilder strBuilder = new StringBuilder();            strBuilder.append("\r\n").append("--").append(BOUNDARY).append("\r\n");            strBuilder.append("Content-Disposition: form-data; name=\"").append(inputName).append("\"; filename=\"").append(filename).append("\"\r\n");            strBuilder.append("Content-Type:").append(contentType).append("\r\n\r\n");

out.write(strBuilder.toString().getBytes());

DataInputStream in = new DataInputStream(inputStream);            int bytes;            byte[] bufferOut = new byte[1024];            while ((bytes = in.read(bufferOut)) != -1) {               out.write(bufferOut, 0, bytes);            }            in.close();         }      }

byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();      out.write(endData);      out.flush();      out.close();

// 读取返回数据      StringBuilder strBuilder = new StringBuilder();      BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));      String line;      while ((line = reader.readLine()) != null) {         strBuilder.append(line).append("\n");      }      res = strBuilder.toString();      reader.close();   } catch (Exception e) {      System.out.println("发送POST请求出错。" + urlStr);      e.printStackTrace();   } finally {      if (conn != null) {         conn.disconnect();      }   }   return res;}