GUID 到 ByteArray

发布于 2024-09-04 05:29:50 字数 1561 浏览 10 评论 0原文

我刚刚编写了这段代码来将 GUID 转换为字节数组。任何人都可以解决其中的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 Java 中没有办法通过内存管理和所有来做到这一点？：

    UUID uuid = UUID.randomUUID();

    long[] longArray = new long[2];
    longArray[0] = uuid.getMostSignificantBits();
    longArray[1] = uuid.getLeastSignificantBits();

    byte[] byteArray = (byte[])longArray;
    return byteArray;

编辑

如果你想生成一个完全随机的 UUID 作为不符合任何的字节官方类型，这将起作用，并且比 UUID.randomUUID() 生成的类型 4 UUID 少10 位：

    public static byte[] getUuidAsBytes(){
    int size = 16;
    byte[] bytes = new byte[size];
    new Random().nextBytes(bytes);
    return bytes;
}

原文

I just wrote this code to convert a GUID into a byte array. Can anyone shoot any holes in it or suggest something better?

 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
       };
}

In C++, I remember being able to do this, but I guess theres no way to do it in Java with the memory management and all?:

    UUID uuid = UUID.randomUUID();

    long[] longArray = new long[2];
    longArray[0] = uuid.getMostSignificantBits();
    longArray[1] = uuid.getLeastSignificantBits();

    byte[] byteArray = (byte[])longArray;
    return byteArray;

Edit

If you want to generate a completely random UUID as bytes that does not conform to any of the official types, this will work and wastes 10 fewer bits than type 4 UUIDs generated by UUID.randomUUID():

    public static byte[] getUuidAsBytes(){
    int size = 16;
    byte[] bytes = new byte[size];
    new Random().nextBytes(bytes);
    return bytes;
}

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捶死心动 2024-09-11 05:29:50

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！）

I would rely on built in functionality:

ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
bb.putLong(uuid.getMostSignificantBits());
bb.putLong(uuid.getLeastSignificantBits());
return bb.array();

or something like,

ByteArrayOutputStream ba = new ByteArrayOutputStream(16);
DataOutputStream da = new DataOutputStream(ba);
da.writeLong(uuid.getMostSignificantBits());
da.writeLong(uuid.getLeastSignificantBits());
return ba.toByteArray();

(Note, untested code!)

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叶落知秋 2024-09-11 05:29:50

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();
}

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();
}

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捂风挽笑 2024-09-11 05:29:50

您可以检查 UUID< /code>来自 apache-commons。您可能不想使用它，但请检查 sources 查看其 getRawBytes() 方法是如何实现的：

public UUID(long mostSignificant, long leastSignificant) {
    rawBytes = Bytes.append(Bytes.toBytes(mostSignificant), Bytes.toBytes(leastSignificant));
}

You can check UUID from apache-commons. You may not want to use it, but check the sources to see how its getRawBytes() method is implemented:

public UUID(long mostSignificant, long leastSignificant) {
    rawBytes = Bytes.append(Bytes.toBytes(mostSignificant), Bytes.toBytes(leastSignificant));
}

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