在Java中将二进制输入流读入单个字节数组 [英] Reading a binary input stream into a single byte array in Java

问题描述

文档表示不应使用 available（）方法来确定 InputStream 的大小。如何将 InputStream 的全部内容读入字节数组？

The documentation says that one should not use available() method to determine the size of an InputStream. How can I read the whole content of an InputStream into a byte array?

InputStream in; //assuming already present
byte[] data = new byte[in.available()];
in.read(data);//now data is filled with the whole content of the InputStream

我可以多次读入固定大小的缓冲区，但是，我必须将读取的数据合并为单个字节数组，这对我来说是一个问题。

I could read multiple times into a buffer of a fixed size, but then, I will have to combine the data I read into a single byte array, which is a problem for me.

推荐答案

最简单的方法IMO是使用番石榴及其 ByteStreams class：

The simplest approach IMO is to use Guava and its ByteStreams class:

byte[] bytes = ByteStreams.toByteArray(in);

或者文件：

byte[] bytes = Files.toByteArray(file);

或者（如果你不想使用Guava），你可以创建 ByteArrayOutputStream ，并重复读入一个字节数组并写入 ByteArrayOutputStream （让它处理大小调整），然后调用 ByteArrayOutputStream.toByteArray（） 。

Alternatively (if you didn't want to use Guava), you could create a ByteArrayOutputStream, and repeatedly read into a byte array and write into the ByteArrayOutputStream (letting that handle resizing), then call ByteArrayOutputStream.toByteArray().

请注意，无论您是否知道输入的长度，这种方法都有效 - 当然，假设您有足够的内存。

Note that this approach works whether you can tell the length of your input or not - assuming you have enough memory, of course.

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