如何一次读取文件x字节?在java中 [英] How do I read file x bytes at a time ? in java

问题描述

我想将文件读入Java的String中，一次x个字符.然后，我将对字符串进行一些操作，并希望从我停下来的地方继续.我该怎么办?

I want to read a file into a String in Java, x chars at a time. Then I'll do something with string, and want to continue from where I left off. How do I go about it ?

目标文件是一个简单的文本文件.

Target file is a simple text file.

推荐答案

首先，您需要区分 bytes 和 characters .您可以一次从InputStream读取一定数量的字节(作为最大数量；不能保证将获得所需的所有字节)，并且可以从Reader读取一个数量一次(最多，最多)个字符.

Well, firstly you need to differentiate between bytes and characters. You can read from an InputStream a certain number of bytes at a time (as a maximum number; there's no guarantee that you'll be given all the bytes that you ask for) and you can read from a Reader a number of characters at a time (again, as a maximum).

听起来像您可能想要在InputStream周围使用InputStreamReader，指定适当的字符编码，然后从InputStreamReader中读取.如果必须有确切个字符，则需要循环-例如:

It sounds like you probably want to use an InputStreamReader around an InputStream, specifying the appropriate character encoding, and then read from the InputStreamReader. If you have to have an exact number of characters, you'd need to loop round - for example:

public static String readExactly(Reader reader, int length) throws IOException {
    char[] chars = new char[length];
    int offset = 0;
    while (offset < length) {
        int charsRead = reader.read(chars, offset, length - offset);
        if (charsRead <= 0) {
            throw new IOException("Stream terminated early");
        }
        offset += charsRead;
    }
    return new String(chars);
}

这篇关于如何一次读取文件x字节?在java中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！