将整个文本文件转换为 Java 中的字符串 [英] Whole text file to a String in Java

问题描述

Java 是否有一行指令来读取文本文件，就像 C# 一样?

Does Java has a one line instruction to read to a text file, like what C# has?

我的意思是，Java 中是否有类似的东西?:

I mean, is there something equivalent to this in Java?:

String data = System.IO.File.ReadAllText("path to file");

如果不是……这样做的最佳方式"是什么……?

If not... what is the 'optimal way' to do this...?

我更喜欢 Java 标准库中的一种方式......我不能使用 3rd 方库..

I prefer a way within Java standard libraries... I can not use 3rd party libraries..

推荐答案

Java 11 通过 Files.readString，示例代码:

Java 11 adds support for this use-case with Files.readString, sample code:

Files.readString(Path.of("/your/directory/path/file.txt"));

在 Java 11 之前，标准库的典型方法是这样的:

Before Java 11, typical approach with standard libraries would be something like this:

public static String readStream(InputStream is) {
    StringBuilder sb = new StringBuilder(512);
    try {
        Reader r = new InputStreamReader(is, "UTF-8");
        int c = 0;
        while ((c = r.read()) != -1) {
            sb.append((char) c);
        }
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
    return sb.toString();
}

注意事项:

• 为了从文件中读取文本，使用 FileInputStream
• 如果性能很重要并且您正在读取大文件，建议将流包装在 BufferedInputStream 中
• 流应该由调用者关闭

• in order to read text from file, use FileInputStream
• if performance is important and you are reading large files, it would be advisable to wrap the stream in BufferedInputStream
• the stream should be closed by the caller

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