我有一个类,它接受ByteBuffer作为构造函数参数。有没有一种方法可以避免进行防御性拷贝,以确保缓冲区在超过该点后不会被修改?
ByteBuffer.isReadOnly()不能保证原来的所有者不会修改缓冲区。更糟糕的是,似乎没有一种方法可以将ByteBuffer子类化。有什么想法吗?
发布于 2012-01-17 23:06:46
这是我目前所能做的最好的事情:
/**
* Helper functions for java.nio.Buffer.
* <p/>
* @author Gili Tzabari
*/
public final class Buffers
{
/**
* Returns a ByteBuffer that is identical but distinct from the original buffer.
* <p/>
* @param original the buffer to copy
* @return an independent copy of original
* @throws NullPointerException if original is null
*/
public static ByteBuffer clone(ByteBuffer original)
{
Preconditions.checkNotNull(original, "original may not be null");
ByteBuffer result = ByteBuffer.allocate(original.capacity());
ByteBuffer source = original.duplicate();
source.rewind();
result.put(source);
try
{
source.reset();
result.position(source.position());
result.mark();
}
catch (InvalidMarkException unused)
{
// Mark is unset, ignore.
}
result.position(original.position());
result.limit(original.limit());
return result;
}
/**
* Returns an array representation of a buffer. The returned buffer may, or may not, be tied to
* the underlying buffer's contents (so it should not be modified).
* <p/>
* @param buffer the buffer
* @return the remaining bytes
*/
public static byte[] toArray(ByteBuffer buffer)
{
if (buffer.hasArray() && !buffer.isReadOnly() && buffer.position() == 0
&& buffer.remaining() == buffer.limit())
{
return buffer.array();
}
ByteBuffer copy = buffer.duplicate();
byte[] result = new byte[copy.remaining()];
copy.get(result);
return result;
}
/**
* Prevent construction.
*/
private Buffers()
{
}
}
我还向甲骨文提交了一个功能请求:http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7130631
发布于 2011-10-03 23:33:04
正如您所说,唯一真正的方法是使用buf.asReadOnlyBuffer()
,然后将其传递给构造函数。除此之外别无选择,尽管您可以将内容复制到一个新的ByteBuffer
中,然后传递它。
发布于 2011-10-03 23:33:09
不会避免复制,但也许:
https://stackoverflow.com/questions/7637105
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