在 Java 中连接两个 ByteBuffer
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Concat two ByteBuffers in Java
提问by mcfly soft
How can I concat two ByteBuffers to one ByteBuffer?
如何将两个 ByteBuffer 连接到一个 ByteBuffer？
The following doesn't work:
以下不起作用：
ByteBuffer bb = ByteBuffer.allocate(100);
ByteBuffer bb2 = ByteBuffer.allocate(200);
bb.allocate(200).put(bb2);
System.out.println(bb.array().length);
The length of bbis still 100.
的长度bb仍然是100。
采纳答案by Marco13
Something like
就像是
bb = ByteBuffer.allocate(300).put(bb).put(bb2);
should do the job: Create a buffer that is large enough to hold the contents of both buffers, and then use the relative put-methods to fill it with the first and the second buffer. (The putmethod returns the instance that the method was called on, by the way)
应该做的工作：创建一个足够大的缓冲区来保存两个缓冲区的内容，然后使用相关的 put-methods 用第一个和第二个缓冲区填充它。（put顺便说一下，该方法返回调用该方法的实例）
回答by Roelof van den Berg
Try the following code:
试试下面的代码：
//store both ByteBuffer object as an array
byte[] array1 = ByteBuffer.allocate(100).array();
byte[] array2 = ByteBuffer.allocate(200).array();
//create a ByteBuffer which is big enough
ByteBuffer bigenough = ByteBuffer.allocate(array1.length + array2.length);
//put the two arrays in one ByteBuffer
ByteBuffer after1 = bigenough.put(array1, 0, array1.length);
ByteBuffer result = after1.put(array2, array1.length, array2.length);
//print the length of the combined array.
System.out.println(result.array().length);
回答by TJR
We'll be copying all data. Remember that this is why string concatenation is expensive!
我们将复制所有数据。请记住，这就是字符串连接成本高昂的原因！
public static ByteBuffer concat(final ByteBuffer... buffers) {
final ByteBuffer combined = ByteBuffer.allocate(Arrays.stream(buffers).mapToInt(Buffer::remaining).sum());
Arrays.stream(buffers).forEach(b -> combined.put(b.duplicate()));
return combined;
}
回答by Z-Y00
you can use the method here
你可以使用这里的方法
and for example:
例如：
ByteBuffer concat() {
int length = 0;
for (ByteBuffer bb : buffers) {
bb.rewind();
length += bb.remaining();
}
ByteBuffer bbNew = ByteBuffer.allocateDirect((int) length);
// put all buffers from list
for (ByteBuffer bb : buffers) {
bb.rewind();
bbNew.put(bb);
}
bbNew.rewind();
return bbNew;
}
回答by Sid_idk
Probably because on line3 i.e. bb.allocate(200).put(bb2);,
可能是因为在3号线，即bb.allocate(200).put(bb2);，
bb.allocate(200)is returning a new Byte buffer (See https://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#allocate(int)). That is not actually changing bbitself. So its still the bytebuffer of capacity 100 from line1.
bb.allocate(200)正在返回一个新的字节缓冲区（参见https://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html#allocate(int)）。这实际上并没有改变bb自己。所以它仍然是第 1 行容量为 100 的字节缓冲区。
