这是我post请求的工具类，请求后的返回的结果是乱码。我用String message = newString(userOpenIds.getBytes(), "UTF-8");转了下结果还是有部分字符是乱码。
如果使用String message = newString(userOpenIds.getBytes("ISO-8859-1"), "UTF-8");结果就会变成全是???(问号)
public static String post(String url, String data) {
    try {
        URL urlObj = new URL(url);
        URLConnection connection = urlObj.openConnection();
        // 要发送数据出去，必须设置为可发送数据状态
        connection.setDoOutput(true);

        OutputStream os = connection.getOutputStream();
        // 写出数据
        os.write(data.getBytes(Charset.forName("utf-8")));
        os.close();
        // 获取输入流
        InputStream is = connection.getInputStream();
        byte[] b = new byte[1024];
        int len;
        StringBuilder sb = new StringBuilder();
        while ((len = is.read(b)) != -1) {
            sb.append(new String(b, 0, len));
        }
        return sb.toString();

    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}