Netty-源码分析ByteBuf-readSlice和readRetainedSlice使用细节

Posted 2022-07-30 征服.刘华强

返回从当前readerIndex开始的此缓冲区的子区域的新分片，并将readerIndex增加新分片的大小（=长度）。
另请注意，此方法将不会调用retain（），因此不会增加引用计数。

 

跟slice极为相似，只是把原始缓冲区的readerIndex进行了增加

@Override
    public ByteBuf readSlice(int length) 
        checkReadableBytes(length);
        ByteBuf slice = slice(readerIndex, length);
        readerIndex += length;
        return slice;
    

public static void main(String[] args) throws Exception 
		ByteBufAllocator allocator = PooledByteBufAllocator.DEFAULT;
		ByteBuf original = allocator.directBuffer(32);
		original.writeByte(1);
		original.writeByte(2);
		original.writeByte(3);
		original.writeByte(4);

		//分配子缓冲区
		ByteBuf sub = original.readSlice(3);

		//原始缓冲区readerIndex=3， readableBytes=1
		System.out.println("org.readerIndex = " + original.readerIndex());
		System.out.println("org.readableBytes = " + original.readableBytes());

		//原始缓冲区引用计数器不变refCnt=1
		System.out.println("org.refCnt=" + original.refCnt());
		//释放一次
		original.release();

 

	public static void main(String[] args) throws Exception 
		ByteBufAllocator allocator = PooledByteBufAllocator.DEFAULT;
		ByteBuf original = allocator.directBuffer(32);
		original.writeByte(1);
		original.writeByte(2);
		original.writeByte(3);
		original.writeByte(4);

		//分配子缓冲区
		ByteBuf sub = original.readRetainedSlice(3);

		//原始缓冲区readerIndex=3， readableBytes=1
		System.out.println("org.readerIndex = " + original.readerIndex());
		System.out.println("org.readableBytes = " + original.readableBytes());

		//原始缓冲区引用计数器改变refCnt=2
		System.out.println("org.refCnt=" + original.refCnt());
		//释放一次
		original.release();

		//子缓冲区再释放一次
		sub.release();
		System.out.println("org.refCnt=" + original.refCnt());

QQ群：212320390