java发送post请求

发送post请求携带参数，但是参数不是key，value类型的

public static String post(String uri, String param) {
        OutputStreamWriter out = null;
        BufferedReader in = null;
        StringBuilder result = new StringBuilder();
        try {
            String encoder = URLEncoder.encode(uri, "UTF-8");
            String decoder = URLDecoder.decode(encoder, "UTF-8");
            URL url = new URL(decoder);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setRequestMethod("POST");
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("content-Type", "text/plain");
            conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            conn.connect();
            out = new OutputStreamWriter(conn.getOutputStream(), StandardCharsets.UTF_8);
            out.write(param);
            out.flush();
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), StandardCharsets.UTF_8));
            String line;
            while ((line = in.readLine()) != null) {
                result.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result.toString();
    }