将所有标准输入读入Java字节数组 [英] Read all standard input into a Java byte array

问题描述

现代Java中最简单的方法（仅使用标准库）将所有标准输入读取到EOF到字节数组中，最好不必自己提供该数组？ stdin数据是二进制数据，不是来自文件。

What's the simplest way in modern Java (using only the standard libraries) to read all of standard input until EOF into a byte array, preferably without having to provide that array oneself? The stdin data is binary stuff and doesn't come from a file.

I.e。 Ruby之类的东西

I.e. something like Ruby's

foo = $stdin.read

我能想到的唯一部分解决方案是

The only partial solution I could think of was along the lines of

byte[] buf = new byte[1000000];
int b;
int i = 0;

while (true) {
    b = System.in.read();
    if (b == -1)
        break;
    buf[i++] = (byte) b;
}

byte[] foo[i] = Arrays.copyOfRange(buf, 0, i);

...但即使对Java来说，这看起来也很奇怪，并使用固定大小的缓冲区。

... but that seems bizarrely verbose even for Java, and uses a fixed size buffer.

推荐答案

我使用番石榴及其 ByteStreams.toByteArray 方法：

I'd use Guava and its ByteStreams.toByteArray method:

byte[] data = ByteStreams.toByteArray(System.in);

如果不使用任何第三方库，我会使用 ByteArrayOutputStream 和一个临时缓冲区：

Without using any 3rd party libraries, I'd use a ByteArrayOutputStream and a temporary buffer:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[32 * 1024];

int bytesRead;
while ((bytesRead = System.in.read(buffer)) > 0) {
    baos.write(buffer, 0, bytesRead);
}
byte[] bytes = baos.toByteArray();

...可能在接受 InputStream ，这基本上等于 ByteStreams.toByteArray 无论如何......

... possibly encapsulating that in a method accepting an InputStream, which would then be basically equivalent to ByteStreams.toByteArray anyway...

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