如何将Java Long转换为Cassandra的byte []？

Question

懒惰的程序员警报。:)

Cassandra将列值存储为字节（Java示例）。指定LongType比较器会将这些字节比较为long。我希望将long的值转换为Cassandra友好的byte
[]。怎么样？我戳了一会儿。我想你们可以帮助我更快。

编辑：

亚历山大和以利的答案都同意这种逆向转变。谢谢！

Answer 1

这是从Java 6中剪切和粘贴的 DataOutputStream.writeLong

public final void writeLong(long v) throws IOException {
    writeBuffer[0] = (byte)(v >>> 56);
    writeBuffer[1] = (byte)(v >>> 48);
    writeBuffer[2] = (byte)(v >>> 40);
    writeBuffer[3] = (byte)(v >>> 32);
    writeBuffer[4] = (byte)(v >>> 24);
    writeBuffer[5] = (byte)(v >>> 16);
    writeBuffer[6] = (byte)(v >>>  8);
    writeBuffer[7] = (byte)(v >>>  0);
    out.write(writeBuffer, 0, 8);
incCount(8);
}

这是您的情况的修改

public final byte[] longToBytes(long v) {
    byte[] writeBuffer = new byte[ 8 ];

    writeBuffer[0] = (byte)(v >>> 56);
    writeBuffer[1] = (byte)(v >>> 48);
    writeBuffer[2] = (byte)(v >>> 40);
    writeBuffer[3] = (byte)(v >>> 32);
    writeBuffer[4] = (byte)(v >>> 24);
    writeBuffer[5] = (byte)(v >>> 16);
    writeBuffer[6] = (byte)(v >>>  8);
    writeBuffer[7] = (byte)(v >>>  0);

    return writeBuffer;
}