在android中使用HttpURLConnection进行文件上传

Posted 2022-11-27 Yingshirun

今天简单说下在android中怎么使用HttpURLConnection进行文件上传
直接上代码：

 

 private final static String LINEND = "\\r\\n";
    private final static String BOUNDARY = "----------fenge"; //数据分隔线
    private final static String PREFIX = "--";
    private final static String MUTIPART_FORMDATA = "multipart/form-data";
    private final static String CONTENTTYPE = "application/octet-stream";
  public static String postFile(String filePath, String url) 
        try 
            URL url_ = new URL(url);        //URL为http://192.168.20.223:8080/s2/20/file/groupheadupload.do?upload=filepath
            HttpURLConnection conn = null;
            //http开头的地址  测试服务器
            conn = (HttpURLConnection) url_.openConnection();

            conn.setDoInput(true);
            conn.setDoOutput(true);
            conn.setUseCaches(false);
            conn.setConnectTimeout(1000 * 60);
            conn.setReadTimeout(1000 * 60);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Charset", "UTF-8");
            conn.setRequestProperty("User-Agent", "Android");
            //这里请求头信息设为 Content-Type: multipart/form-data; boundary=----------fenge      
            //boundary 为设置文件分割标志
            conn.setRequestProperty("Content-Type", MUTIPART_FORMDATA + "; boundary=" + BOUNDARY);

            File file = new File(filePath);
            DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
            StringBuilder sb = new StringBuilder();
            /**
             * 首先向服务器写出请求表单：
             * ------------fenge
             * Content-Disposition: form-data; name="upload"; filename="文件名称"\\r\\n
             * Content-Type:application/octet-stream\\r\\n
             * Content-Transfer-Encoding: binary\\r\\n\\r\\n
             */
            sb.append(PREFIX + BOUNDARY + LINEND);
            sb.append("Content-Disposition: form-data; name=\\"upload" + "\\"; filename=\\"" + file.getName() + "\\"" + LINEND);
            sb.append("Content-Type:" + CONTENTTYPE + LINEND);
            sb.append("Content-Transfer-Encoding: binary" + LINEND + LINEND);
            dos.write(sb.toString().getBytes());

            /**
             * 接着写文件
             */
            BufferedInputStream bs = new BufferedInputStream(new FileInputStream(file));
            int len = 0;
            byte[] buf = new byte[1024 * 1024];
            while ((len = bs.read(buf)) != -1) 
                dos.write(buf, 0, len);
            
            bs.close();
            /**
             * 最后写出结束标志
             * \\r\\n------------fenge--\\r\\n
             */
            //请求结束标志
            byte[] end_data = (LINEND + PREFIX + BOUNDARY + PREFIX + LINEND).getBytes();
            dos.write(end_data);
            dos.flush();
            dos.close();
            //上传完成 介绍返回值

            /**
             * 到这里算是上传完成
             * 最后读取服务器的返回信息
             */
            int code = conn.getResponseCode();
            if (code == 200) 
                InputStream input = conn.getInputStream();
                BufferedReader bis = new BufferedReader(new InputStreamReader(input));
                StringBuilder ssb = new StringBuilder();
                String line = null;
                while ((line = bis.readLine()) != null) 
                    ssb.append(line);
                
                bis.close();
                conn.disconnect();
                return ssb.toString();
            
         catch (MalformedURLException e) 
            e.printStackTrace();
         catch (IOException e) 
            e.printStackTrace();
        
        return "";
    

这里说一下我遇到的坑：

在请求头里定义Content-Type 时，设置的boundary

在向服务器发送请求的时候，一定要在boundary的前面多加上两个减号 --

如：--boundary

在文件发送完后 要在boundary的后面多加上两个减号作为结束标志

如:--boundary--