如何将File对象转换为Netty ByteBuffer

有没有办法从java File对象中获取netty ByteBuf？我正在尝试使用Custom Snappy类来验证校验和.下面是我的代码,我想File在bytebuf变量中获取对象.

import io.netty.buffer.ByteBuf;

File file = new File("boot.zip");
ByteBuf byteBuf = Unpooled.buffer(128);
byteBuf.writeBytes(new FileInputStream(file));
int expectedChecksum = Snappy.calculateChecksum(byteBuf);
logger.info("checksum = "+expectedChecksum);

boolean checksumValid = true;
try {       
    CustomSnappy.validateChecksum(expectedChecksum, byteBuf);
} catch(DecompressionException e) {
    checksumValid = false;
    e.printStackTrace();
    logger.error("DecompressionException in checksum calculation " + e);            
} catch(Exception e) {
    checksumValid = false;
    e.printStackTrace();
    logger.error("Exception in checksum calculation " + e);
}

我使用了Unpooled.buffer(128),但它给了我 No signature of method :io.netty.buffer.UnpooledHeapByteBuf.writeBytes() is applicable for argument types: (java.io.FileInputStream) values: [java.io.FileInputStream@28b6520b]