你如何决定用于InputStream.read（）的byte []大小？ [英] How do you decide what byte[] size to use for InputStream.read()?

问题描述

从InputStreams读取时，如何确定byte []的大小？

When reading from InputStreams, how do you decide what size to use for the byte[]?

int nRead;
byte[] data = new byte[16384]; // <-- this number is the one I'm wondering about

while ((nRead = is.read(data, 0, data.length)) != -1) {
  ...do something..
}

你什么时候用一个小的对一个大的？有什么区别？数字是否需要以1024为增量？如果它是来自网络和磁盘的InputStream会有所不同吗？

When do you use a small one vs a large one? What are the differences? Does the number want to be in increments of 1024? Does it make a difference if it is an InputStream from the network vs the disk?

非常感谢，我似乎无法在其他地方找到明确的答案。

Thanks much, I can't seem to find a clear answer elsewhere.

推荐答案

大多数人使用2的幂来表示大小。
如果缓冲区至少为512字节，则没有太大区别（<20％）

Most people use powers of 2 for the size. If the buffer is at least 512 bytes, it doesn't make much difference ( < 20% )

对于网络，最佳大小可以是2 KB到8 KB（底层数据包大小通常高达~1.5 KB）对于磁盘访问，最快的大小可以是8K到64 KB。如果您使用8K或16K，则不会有问题。

For network the optimal size can be 2 KB to 8 KB (The underlying packet size is typically up to ~1.5 KB) For disk access, the fastest size can be 8K to 64 KB. If you use 8K or 16K you won't have a problem.

注意网络下载，您可能会发现通常不使用整个缓冲区。对于99％的用例而言，浪费几KB并不重要。

Note for network downloads, you are likely to find you usually don't use the whole buffer. Wasting a few KB doesn't matter much for 99% of use cases.

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