FileUtil.java

package io.bitsquare.storage;

import com.google.common.io.Files;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.Date;
import java.util.List;

public class FileUtil {
    private static final Logger log = LoggerFactory.getLogger(FileUtil.class);

    public static void rollingBackup(File dir, String fileName, int numMaxBackupFiles) {
        if (dir.exists()) {
            File backupDir = new File(Paths.get(dir.getAbsolutePath(), "backup").toString());
            if (!backupDir.exists())
                if (!backupDir.mkdir())
                    log.warn("make dir failed.\nBackupDir=" + backupDir.getAbsolutePath());

            File origFile = new File(Paths.get(dir.getAbsolutePath(), fileName).toString());
            if (origFile.exists()) {
                String dirName = "backups_" + fileName;
                if (dirName.contains("."))
                    dirName = dirName.replace(".", "_");
                File backupFileDir = new File(Paths.get(backupDir.getAbsolutePath(), dirName).toString());
                if (!backupFileDir.exists())
                    if (!backupFileDir.mkdir())
                        log.warn("make backupFileDir failed.\nBackupFileDir=" + backupFileDir.getAbsolutePath());

                File backupFile = new File(Paths.get(backupFileDir.getAbsolutePath(), new Date().getTime() + "_" + fileName).toString());

                try {
                    Files.copy(origFile, backupFile);

                    pruneBackup(backupFileDir, numMaxBackupFiles);
                } catch (IOException e) {
                    log.error("Backup key failed: " + e.getMessage());
                    e.printStackTrace();
                }
            }
        }
    }

    private static void pruneBackup(File backupDir, int numMaxBackupFiles) {
        if (backupDir.isDirectory()) {
            File[] files = backupDir.listFiles();
            if (files != null) {
                List<File> filesList = Arrays.asList(files);
                if (filesList.size() > numMaxBackupFiles) {
                    filesList.sort((o1, o2) -> o1.getName().compareTo(o2.getName()));
                    File file = filesList.get(0);
                    if (file.isFile()) {
                        if (!file.delete())
                            log.error("Failed to delete file: " + file);
                        else
                            pruneBackup(backupDir, numMaxBackupFiles);

                    } else {
                        pruneBackup(new File(Paths.get(backupDir.getAbsolutePath(), file.getName()).toString()), numMaxBackupFiles);
                    }
                }
            }
        }
    }

    public static void deleteDirectory(File file) throws IOException {
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            if (files != null)
                for (File c : files)
                    deleteDirectory(c);
        }
        if (file.exists() && !file.delete())
            throw new FileNotFoundException("Failed to delete file: " + file);
    }

    public static void resourceToFile(String resourcePath, File destinationFile) throws ResourceNotFoundException, IOException {
        InputStream inputStream = ClassLoader.getSystemClassLoader().getResourceAsStream(resourcePath);
        if (inputStream == null)
            throw new ResourceNotFoundException(resourcePath);

        try (FileOutputStream fileOutputStream = new FileOutputStream(destinationFile)) {
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                fileOutputStream.write(buffer, 0, bytesRead);
            }
        } catch (IOException e) {
            throw e;
        }
    }
}