How does Java I/O stream perform file metadata operations?

Java I/O streams can operate on file and directory metadata, including creation date, modification date, file size, etc. Metadata operations can be performed through the Files class or the File class. This article demonstrates how to use the Files and File classes to obtain the creation time and size of files respectively, and how to use the Files class to obtain the creation dates of all files in the current directory in batches.

Metadata operations of Java I/O streams

Java I/O streams provide operations on file and directory metadata. Ability to operate. Metadata information usually includes the creation date, modification date, file size, etc. of the file or directory.

Use the Files class to manipulate metadata

Java 7 and later versions provide the easy-to-use Files class, Provides a rich API to manipulate file and directory metadata.

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;

public class FileMetadataExample {

    public static void main(String[] args) throws Exception {
        // 获取文件路径
        Path filePath = Paths.get("test.txt");

        // 获取文件基本属性
        BasicFileAttributes attrs = Files.readAttributes(filePath, BasicFileAttributes.class);

        // 输出文件元数据
        System.out.println("文件大小：" + attrs.size());
        System.out.println("创建时间：" + attrs.creationTime());
        System.out.println("修改时间：" + attrs.lastModifiedTime());
    }
}

Use the File class to manipulate metadata

In Java, the File class also provides file metadata access, but its API is not as rich as the Files class.

import java.io.File;

public class FileMetadataExample {

    public static void main(String[] args) {
        // 获取文件
        File file = new File("test.txt");

        // 输出文件元数据
        System.out.println("文件大小：" + file.length());
        System.out.println("创建时间：" + file.lastModified());
    }
}

Practical case

Suppose we need to write a program to get the creation date of all files in the current directory.

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;

public class FileListMetadataExample {

    public static void main(String[] args) throws Exception {
        // 获取当前目录
        Path dirPath = Paths.get(".");

        // 遍历目录中的所有文件
        Files.list(dirPath).forEach(path -> {
            // 获取文件基本属性
            try {
                BasicFileAttributes attrs = Files.readAttributes(path, BasicFileAttributes.class);
                
                // 输出文件信息
                System.out.println(path.getFileName() + ": " + attrs.creationTime());
            } catch (Exception e) {
                // 忽略错误
            }
        });
    }
}

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