public int readRawLittleEndian32() throws IOException {
        final byte[] bs = new byte[4];
        nioBuffer.get(bs);

        return (((int) bs[0] & 0xff)) | (((int) bs[1] & 0xff) << 8) | (((int) bs[2] & 0xff) << 16)
               | (((int) bs[3] & 0xff) << 24);
    }
Read a 32-bit little-endian integer from the internal buffer.
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/serialization/impl/protostuff/io/NioBufInput.java