Java 文件操作全指南：读写、复制、压缩与实战应用

java复制编辑import java.io.File;

public class FileCheck {
    public static void main(String[] args) {
        File file = new File("example.txt");

        System.out.println("文件是否存在: " + file.exists());
        System.out.println("是否是文件: " + file.isFile());
        System.out.println("是否是目录: " + file.isDirectory());
        System.out.println("文件大小（字节）: " + file.length());
        System.out.println("绝对路径: " + file.getAbsolutePath());
    }
}

java复制编辑import java.io.*;
import java.nio.file.*;

public class FileReaderExample {
    public static void main(String[] args) throws IOException {
        Path path = Paths.get("data.txt");

        Files.lines(path).forEach(System.out::println);
    }
}

java复制编辑Files.write(Paths.get("output.txt"),
            "写入内容".getBytes(),
            StandardOpenOption.CREATE, StandardOpenOption.APPEND);

java复制编辑Path src = Paths.get("source.txt");
Path dest = Paths.get("copy.txt");
Files.copy(src, dest, StandardCopyOption.REPLACE_EXISTING);

java复制编辑Files.deleteIfExists(Paths.get("copy.txt"));

java复制编辑Files.walk(Paths.get("tempDir"))
     .sorted(Comparator.reverseOrder())
     .forEach(path -> {
         try {
             Files.delete(path);
         } catch (IOException e) {
             e.printStackTrace();
         }
     });

java复制编辑try (BufferedReader reader = new BufferedReader(new FileReader("large.txt"))) {
    String line;
    while ((line = reader.readLine()) != null) {
        System.out.println(line);
    }
}

java复制编辑try (FileOutputStream fos = new FileOutputStream("image_copy.jpg")) {
    byte[] bytes = Files.readAllBytes(Paths.get("image.jpg"));
    fos.write(bytes);
}

java复制编辑import java.util.zip.*;

public class ZipExample {
    public static void main(String[] args) throws IOException {
        try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream("archive.zip"))) {
            ZipEntry entry = new ZipEntry("hello.txt");
            zos.putNextEntry(entry);
            byte[] data = "这是文件内容".getBytes();
            zos.write(data);
            zos.closeEntry();
        }
    }
}

java复制编辑try (ZipInputStream zis = new ZipInputStream(new FileInputStream("archive.zip"))) {
    ZipEntry entry;
    while ((entry = zis.getNextEntry()) != null) {
        Files.copy(zis, Paths.get(entry.getName()), StandardCopyOption.REPLACE_EXISTING);
    }
}

java复制编辑Files.walk(Paths.get("logs"))
     .filter(p -> p.toString().endsWith(".log"))
     .forEach(System.out::println);

java复制编辑public class LogArchiver {
    public static void main(String[] args) throws IOException {
        String logFile = "server.log";
        String archiveName = "log_" + System.currentTimeMillis() + ".zip";

        try (ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(archiveName))) {
            ZipEntry entry = new ZipEntry("server.log");
            zos.putNextEntry(entry);
            Files.copy(Paths.get(logFile), zos);
            zos.closeEntry();
        }

        Files.delete(Paths.get(logFile)); // 删除原始日志
    }
}

java复制编辑WatchService watchService = FileSystems.getDefault().newWatchService();
Path path = Paths.get("watched_folder");
path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE,
              StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);

WatchKey key;
while ((key = watchService.take()) != null) {
    for (WatchEvent<?> event : key.pollEvents()) {
        System.out.println("事件类型：" + event.kind());
        System.out.println("发生文件：" + event.context());
    }
    key.reset();
}