将byte []附加到另一个byte []的末尾

Question

我有两个byte[]长度未知的数组,我只想将一个附加到另一个的末尾,即:

byte[] ciphertext = blah;
byte[] mac = blah;
byte[] out = ciphertext + mac;

我试过使用arraycopy()但似乎无法让它工作.

Answer 1

使用System.arraycopy(),类似下面的东西应该工作:

// create a destination array that is the size of the two arrays
byte[] destination = new byte[ciphertext.length + mac.length];

// copy ciphertext into start of destination (from pos 0, copy ciphertext.length bytes)
System.arraycopy(ciphertext, 0, destination, 0, ciphertext.length);

// copy mac into end of destination (from pos ciphertext.length, copy mac.length bytes)
System.arraycopy(mac, 0, destination, ciphertext.length, mac.length);

Answer 2

也许最简单的方法:

ByteArrayOutputStream output = new ByteArrayOutputStream();

output.write(ciphertext);
output.write(mac);

byte[] out = output.toByteArray();

Answer 3

您需要声明out一个长度等于长度ciphertext并mac加在一起的字节数组,然后使用arraycopy 复制ciphertext开头out和mac结尾.

byte[] concatenateByteArrays(byte[] a, byte[] b) {
    byte[] result = new byte[a.length + b.length]; 
    System.arraycopy(a, 0, result, 0, a.length); 
    System.arraycopy(b, 0, result, a.length, b.length); 
    return result;
} 

Answer 4

当你想只添加2个字节数组时,其他提供的解决方案很棒,但如果你想继续添加几个byte []块来制作一个:

byte[] readBytes ; // Your byte array .... //for eg. readBytes = "TestBytes".getBytes();

ByteArrayBuffer mReadBuffer = new ByteArrayBuffer(0 ) ; // Instead of 0, if you know the count of expected number of bytes, nice to input here

mReadBuffer.append(readBytes, 0, readBytes.length); // this copies all bytes from readBytes byte array into mReadBuffer
// Any new entry of readBytes, you can just append here by repeating the same call.

// Finally, if you want the result into byte[] form:
byte[] result = mReadBuffer.buffer();

Answer 5

首先,您需要分配组合长度的数组,然后使用arraycopy从两个源填充它.

byte[] ciphertext = blah;
byte[] mac = blah;
byte[] out = new byte[ciphertext.length + mac.length];


System.arraycopy(ciphertext, 0, out, 0, ciphertext.length);
System.arraycopy(mac, 0, out, ciphertext.length, mac.length);