网络编程，工具类

/**
     * 从输入流获取数据
     * @throws Exception 
     */
    public static byte[] readInputStram(InputStream inputStream) throws Exception{
        byte[] buffer = new byte[1024];
        int len = -1;
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        while((len = inputStream.read(buffer)) != -1){
            outStream.write(buffer, 0, len);
        }
        outStream.close();
        inputStream.close();
        return outStream.toByteArray();
    }

/**
     *直接通过http协议提交表单到服务器。
     *FormFile 文件  struts的Formfile(//import org.apache.struts.upload.FormFile;)
     */
    public static String post(String actionUrl, Map<String, String> params, FormFile[] files){
        try {
            String BOUNDARY = "---------7d4a6d158c9";//数据分割线
            String MULTIPART_FORM_DATA = "multipart/form-data";
            URL url = new URL(actionUrl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(5 * 1000);
            conn.setDoInput(true);//允许输入
            conn.setDoOutput(true);//允许输出
            conn.setUseCaches(false);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("Charset", "UTF-8");
            conn.setRequestProperty("Content-Type", MULTIPART_FORM_DATA + "; boundary-" + BOUNDARY);
            StringBuilder sb = new StringBuilder();
            for(Map.Entry<String, String> entry : params.entrySet()){
                sb.append("--");
                sb.append(BOUNDARY);
                sb.append("
");
                sb.append("Content-Disposition: form-data; name="" + entry.getKey() + "

");
                sb.append(entry.getValue());
                sb.append("
");
            }
            DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());
            outStream.write(sb.toString().getBytes());//发送表单字段
            for(FormFile file : files){
                StringBuilder split = new StringBuilder();
                split.append("--");
                split.append(BOUNDARY);
                split.append("
");
                split.append("Content-Disposition: form-data;name="" + file.getFormname() + "";filename=""+file.getFilename() + ""
");
                split.append("Content-Type: " + file.getContentType()+"

");
                outStream.write(split.toString().getBytes());
                if(file.getInStream() != null){
                    byte[] buffer = new byte[1024];
                    int len = 0;
                    while((len = file.getInStream().read(buffer)) != -1){
                        outStream.write(buffer, 0, len);
                    }
                    file.getInStream().close();
                }else{
                    outStream.write(file.getData(), 0, file.getData(),length);
                }
                outStream.write("
".getBytes());
            }
            byte[] end_data = ("--" + BOUNDARY + "--
").getBytes();
            outStream.write(end_data);
            outStream.flush();
            int cah = conn.getResponseCode();
            if(cah != 200)
                throw new RuntimeException("请求url失败");
            InputStream is = conn.getInputStream();
            int ch;
            StringBuilder b = new StringBuilder();
            while((ch = is.read()) != -1){
                b.append((char)ch);
            }
            outStream.close();
            conn.disconnect();
            return b.toString();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }