如何加快从 InputStream 到 java.net Socket 的读取数据？

有一个 java.net 套接字

    private Socket clientSocket;
    private BufferedReader is;
    private Writer out;

    public ClientServiceThread(Socket clientSocket) throws IOException {
        this.clientSocket = clientSocket;
        clientSocket.setTcpNoDelay(true);

        this.is = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        this.out = new OutputStreamWriter(this.clientSocket.getOutputStream(), "UTF-8");

        String str = convert(is);
    }

通过socket接收到的Base64数据量比较大。

读取数据需要很长时间。

public String convert(BufferedReader reader) throws IOException {

        StringBuilder stringBuilder = new StringBuilder();
        String line = null;

            while ((line = reader.readLine()) != null) {
                stringBuilder.append(line);

        }

        return stringBuilder.toString();
    }

如何正确、高效地读取数据，即更快地读取数据？