用java写一个备份文件的代码

在Java中，我们可以创建一个简单的工具类来备份文件。下面是一个基本的示例，它使用`java.io`包里的`FileInputStream`、`FileOutputStream`和`FileUtils`来自Apache Commons IO库来进行文件复制操作。首先，确保已添加了Apache Commons IO依赖。

import org.apache.commons.io.FileUtils;

public class FileBackup {
    public static void backupFile(String sourcePath, String destinationPath) throws Exception {
        // 检查源文件是否存在
        if (!new File(sourcePath).exists()) {
            throw new FileNotFoundException("Source file does not exist at " + sourcePath);
        }

        // 创建目标目录如果不存在
        if (!new File(destinationPath).mkdirs() && !new File(destinationPath).isDirectory()) {
            throw new IOException("Failed to create directory at " + destinationPath);
        }

        // 开始备份过程
        try (FileInputStream in = new FileInputStream(sourcePath);
             FileOutputStream out = new FileOutputStream(destinationPath)) {

            FileUtils.copyFile(in, out);
            System.out.println("File backed up successfully from " + sourcePath + " to " + destinationPath);

        } catch (IOException e) {
            System.err.println("Error occurred while backing up file: " + e.getMessage());
        }
    }
}

// 调用示例
public static void main(String[] args) {
    try {
        FileBackup.backupFile("path/to/source/file", "path/to/backup/directory");
    } catch (Exception e) {
        e.printStackTrace();
    }
}