jvm源码分析之FileChannel.transferTo()方法

最新推荐文章于 2025-05-30 11:27:48 发布

zhifeng687

最新推荐文章于 2025-05-30 11:27:48 发布

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分类专栏： Java

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FileChannel.transferTo()方法

public abstract long transferTo(long position, long count,
                                    WritableByteChannel target)
        throws IOException;

FileChannelImpl.transferTo()方法

public long transferTo(long position, long count,
                           WritableByteChannel target)
        throws IOException
    {
        ensureOpen();
        if (!target.isOpen())
            throw new ClosedChannelException();
        if (!readable)
            throw new NonReadableChannelException();
        if (target instanceof FileChannelImpl &&
            !((FileChannelImpl)target).writable)
            throw new NonWritableChannelException();
        if ((position < 0) || (count < 0))
            throw new IllegalArgumentException();
        long sz = size();
        if (position > sz)
            return 0;
        int icount = (int)Math.min(count, Integer.MAX_VALUE);
        if ((sz - position) < icount)
            icount = (int)(sz - position);

        long n;

        // Attempt a direct transfer, if the kernel supports it
        if ((n = transferToDirectly(position, icount, target)) >= 0)
            return n;

        // Attempt a mapped transf