Java中File的用法_Java中文件操作的指南

File file = new File("path/to/your/file.txt"); // 相对路径
File absoluteFile = new File("/absolute/path/to/your/file.txt"); // 绝对路径
File dir = new File("path/to/your/directory");

try {
    if (file.createNewFile()) {
        System.out.println("File created: " + file.getName());
    } else {
        System.out.println("File already exists.");
    }
} catch (IOException e) {
    System.err.println("An error occurred: " + e.getMessage());
}

if (dir.mkdir()) { // 创建单层目录
    System.out.println("Directory created: " + dir.getName());
} else {
    System.out.println("Failed to create directory.");
}

if (dir.mkdirs()) { // 创建多层目录
    System.out.println("Directories created: " + dir.getName());
} else {
    System.out.println("Failed to create directories.");
}

if (file.exists()) {
    System.out.println("File exists.");
} else {
    System.out.println("File does not exist.");
}

if (file.delete()) {
    System.out.println("File deleted: " + file.getName());
} else {
    System.out.println("Failed to delete file.");
}

File newFile = new File("path/to/your/new_file.txt");
if (file.renameTo(newFile)) {
    System.out.println("File renamed successfully.");
} else {
    System.out.println("Failed to rename file.");
}

System.out.println("File name: " + file.getName());
System.out.println("Absolute path: " + file.getAbsolutePath());
System.out.println("File size: " + file.length() + " bytes");
System.out.println("Last modified: " + new Date(file.lastModified()));

File directory = new File("path/to/your/directory");
String[] fileList = directory.list(); // 返回字符串数组，包含文件名
File[] files = directory.listFiles(); // 返回File对象数组

if (files != null) {
    for (File f : files) {
        System.out.println(f.getName() + (f.isFile() ? " (file)" : " (directory)"));
    }
}

try {
    // 文件操作代码，例如创建、读取、写入文件
    FileInputStream fis = new FileInputStream("myfile.txt");
    // ... 其他操作
    fis.close(); // 始终确保关闭流
} catch (FileNotFoundException e) {
    // 文件未找到的处理
    System.err.println("文件未找到：" + e.getMessage());
} catch (IOException e) {
    // 其他IO异常的处理
    System.err.println("IO异常：" + e.getMessage());
    // 可以尝试重试，记录日志，或者通知用户
} finally {
    // 无论是否发生异常，都应该执行的代码，通常用于关闭资源
    // 例如，关闭FileInputStream, FileOutputStream等
    // 确保资源被释放，防止内存泄漏
    try {
        if (fis != null) {
            fis.close(); // 关闭流，即使在try块中发生异常
        }
    } catch (IOException ex) {
        System.err.println("关闭流时发生异常：" + ex.getMessage());
    }
}

File file = new File("path/to/your/file_or_directory");

if (file.exists()) {
    if (file.isFile()) {
        System.out.println("This is a file.");
    } else if (file.isDirectory()) {
        System.out.println("This is a directory.");
    } else {
        System.out.println("This is neither a file nor a directory."); // 可能是特殊文件
    }
} else {
    System.out.println("File/directory does not exist.");
}

import java.io.File;

public class DirectoryTraversal {

    public static void traverseDirectory(File directory) {
        if (!directory.isDirectory()) {
            System.out.println("Not a directory: " + directory.getAbsolutePath());
            return;
        }

        File[] files = directory.listFiles(); // 获取目录下的所有文件和子目录

        if (files != null) {
            for (File file : files) {
                if (file.isFile()) {
                    System.out.println("File: " + file.getAbsolutePath());
                    // 对文件进行处理
                } else if (file.isDirectory()) {
                    System.out.println("Directory: " + file.getAbsolutePath());
                    traverseDirectory(file); // 递归调用
                }
            }
        } else {
            System.err.println("Could not list files in directory: " + directory.getAbsolutePath());
        }
    }

    public static void main(String[] args) {
        File dir = new File("path/to/your/directory");
        traverseDirectory(dir);
    }
}

File relativeFile = new File("documents/myfile.txt"); // 相对路径
File absoluteFile = new File("/home/user/documents/myfile.txt"); // 绝对路径

System.out.println("Relative file absolute path: " + relativeFile.getAbsolutePath());
System.out.println("Absolute file absolute path: " + absoluteFile.getAbsolutePath());

System.out.println("Relative file canonical path: " + getCanonicalPath(relativeFile));
System.out.println("Absolute file canonical path: " + getCanonicalPath(absoluteFile));