[PHP知识库]Java的File类和Path类使用注意事项

• 一个File对象isDirectory和isFile可以同时是false（在文件不存在的时候）

File file = new File("/export/不存在的文件.txt");
System.out.println("isDirectory:" + file.isDirectory());
System.out.println("isFile:" + file.isFile());

上面的代码执行输出

isDirectory:false
isFile:false

• Path的of和resolve方法分别用于String的路径拼接，Path和String的路径拼接；relativize可以实现相反的过程。

Path dirPath = Path.of("/export", "test");
System.out.println(dirPath);
Path filePath = dirPath.resolve("a.txt");
System.out.println(filePath);
System.out.println(dirPath.relativize(filePath));

如上代码输出

/export/test
/export/test/a.txt
a.txt

• Files读写文件字符串的编码默认是UTF8，并不是系统默认编码

public static Path writeString(Path path, CharSequence csq, OpenOption... options) throws IOException{
    return writeString(path, csq, UTF_8.INSTANCE, options);
}

public static String readString(Path path) throws IOException {
    return readString(path, UTF_8.INSTANCE);
}