用HttpURLConnection来完成HTTP发送报文接收报文！

public  String sendMsg(String url, byte[] PostData) {
        String content = null;
        URL urls = null;
        try {
        urls = new URL(url);
        HttpURLConnection httpURLConnection = (HttpURLConnection) urls .openConnection();
         // 设置连接时间
        httpURLConnection.setConnectTimeout(3000);
        // 打开输入流，以便从服务器获取数据
        httpURLConnection.setDoInput(true);
        // 打开输出流，以便向服务器提交数据
        httpURLConnection.setDoOutput(true);
         // 设置以POST方式提交数据
        httpURLConnection.setRequestMethod("POST");
        // 使用POST不能使用缓存
        httpURLConnection.setUseCaches(false);
        // 设置请求的类型是文本类型
        httpURLConnection.setRequestProperty("Content-Type",
        "application/x-www-form-urlencoded");
        // 设置请求体的长度
        httpURLConnection.setRequestProperty("Content-Length",
        String.valueOf(PostData.length));
        // 获得输出流，向指定的Url写入数据
        OutputStream outputStream = httpURLConnection.getOutputStream();
        outputStream.write(PostData);
        int response = httpURLConnection.getResponseCode(); 
                // 获得服务器响应码
        if (response == HttpURLConnection.HTTP_OK) {
        InputStream inputStream= httpURLConnection.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "gbk"));
                        StringBuilder builder = new StringBuilder();
                        String line = null;
                        while ((line = reader.readLine()) != null) {
                            builder.append(line).append("
");
                        }
                        content = builder.toString();
                    }
        }catch (IOException e) {
        e.printStackTrace();
        }
        return content;
        }