我刚编写此代码以将GUID转换为字节数组。任何人都可以在其中拍摄任何漏洞或提出更好的建议吗?
public static byte[] getGuidAsByteArray(){
UUID uuid = UUID.randomUUID();
long longOne = uuid.getMostSignificantBits();
long longTwo = uuid.getLeastSignificantBits();
return new byte[] {
(byte)(longOne >>> 56),
(byte)(longOne >>> 48),
(byte)(longOne >>> 40),
(byte)(longOne >>> 32),
(byte)(longOne >>> 24),
(byte)(longOne >>> 16),
(byte)(longOne >>> 8),
(byte) longOne,
(byte)(longTwo >>> 56),
(byte)(longTwo >>> 48),
(byte)(longTwo >>> 40),
(byte)(longTwo >>> 32),
(byte)(longTwo >>> 24),
(byte)(longTwo >>> 16),
(byte)(longTwo >>> 8),
(byte) longTwo
};
}
在C ++中,我记得能够做到这一点,但我想在内存管理方面没有办法在Java中做到这一点吗?:
UUID uuid = UUID.randomUUID();
long[] longArray = new long[2];
longArray[0] = uuid.getMostSignificantBits();
longArray[1] = uuid.getLeastSignificantBits();
byte[] byteArray = (byte[])longArray;
return byteArray;
如果你想生成一个完全随机的UUID作为不符合任何官方类型的字节,这将比UUID.randomUUID()生成的类型4 UUID更有效,浪费10 fewer bits:
public static byte[] getUuidAsBytes(){
int size = 16;
byte[] bytes = new byte[size];
new Random().nextBytes(bytes);
return bytes;
}
答案 0 :(得分:64)
我会依赖内置功能:
ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
bb.putLong(uuid.getMostSignificantBits());
bb.putLong(uuid.getLeastSignificantBits());
return bb.array();
或类似的东西,
ByteArrayOutputStream ba = new ByteArrayOutputStream(16);
DataOutputStream da = new DataOutputStream(ba);
da.writeLong(uuid.getMostSignificantBits());
da.writeLong(uuid.getLeastSignificantBits());
return ba.toByteArray();
(注意,未经测试的代码!)
答案 1 :(得分:13)
public static byte[] newUUID() {
UUID uuid = UUID.randomUUID();
long hi = uuid.getMostSignificantBits();
long lo = uuid.getLeastSignificantBits();
return ByteBuffer.allocate(16).putLong(hi).putLong(lo).array();
}
答案 2 :(得分:4)
您可以从apache-commons查看UUID
。您可能不想使用它,但请检查sources以查看其getRawBytes()
方法的实施方式:
public UUID(long mostSignificant, long leastSignificant) {
rawBytes = Bytes.append(Bytes.toBytes(mostSignificant), Bytes.toBytes(leastSignificant));
}
答案 3 :(得分:0)
你可以看看Apache Commons Lang3 Conversion.uuidToByteArray(...)。相反,请查看Conversion.byteArrayToUuid(...)以转换回UUID。