FileUtil.java

package com.ctriposs.bigcache.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class FileUtil {
	
	private static final int BUFFER_SIZE = 4096 * 4;
	
	/**
	 * Only check if a given filename is valid according to the OS rules.
	 * 
	 * You still need to handle other failures when actually creating 
	 * the file (e.g. insufficient permissions, lack of drive space, security restrictions). 
	 * @param file the name of a file
	 * @return true if the file is valid, false otherwise
	 */
	public static boolean isFilenameValid(String file) {
		File f = new File(file);
		try {
			f.getCanonicalPath();
			return true;
		} catch (IOException e) {
			return false;
		}
	}
	
    public static void deleteDirectory(File dir) {
        if (!dir.exists()) return;
        File[] subs = dir.listFiles();
        if (subs != null) {
            for (File f : dir.listFiles()) {
                if (f.isFile()) {
                    if(!f.delete()) {
                        throw new IllegalStateException("delete file failed: "+f);
                    }
                } else {
                    deleteDirectory(f);
                }
            }
        }
        if(!dir.delete()) {
            throw new IllegalStateException("delete directory failed: "+dir);
        }
    }
    
    public static void deleteFile(File file) {
    	if (!file.exists() || !file.isFile()) {
    		return;
    	}
    	if (!file.delete()) {
            throw new IllegalStateException("delete file failed: "+file);
    	}
    }
    
    /**
     * Copy a directory and all of its contents.
     * 
     * @param from source file
     * @param to target file
     * @return success or failure
     */
    public static boolean copyDirectory(File from, File to) {
    	return copyDirectory(from, to, (byte[]) null);
    }
    
    public static boolean copyDirectory(String from, String to) {
    	return copyDirectory(new File(from), new File(to));
    }
    
    public static boolean copyDirectory(File from, File to, byte[] buffer) {
    	if (from == null) return false;
    	if (!from.exists()) return true;
    	if (!from.isDirectory()) return false;
    	if (to.exists()) return false;
    	if (!to.mkdirs()) return false;
    	
    	String[] list = from.list();
    	// Some JVMs return null for File.list() when the directory is empty.
    	if (list != null) {
    		if (buffer == null) buffer = new byte[BUFFER_SIZE]; // return this buffer to copy files
    		
    		for(int i = 0; i < list.length; i++) {
    			String fileName = list[i];
    			
    			File entry = new File(from, fileName);
    			
    			if (entry.isDirectory()) {
    				if (!copyDirectory(entry, new File(to, fileName), buffer)) {
    					return false;
    				} 
    			}
    			else {
    				if (!copyFile(entry, new File(to, fileName), buffer)) {
    					return false;
    				}
    			}
    		}
    	}
    	
    	return true;
    }
    
    public static boolean copyFile(File from, File to, byte[] buf) {
    	if (buf == null) buf = new byte[BUFFER_SIZE];
    	
    	FileInputStream from_s = null;
    	FileOutputStream to_s = null;
    	
    	try {
    		from_s = new FileInputStream(from);
    		to_s = new FileOutputStream(to);
    		
    		for(int bytesRead = from_s.read(buf); bytesRead > 0; bytesRead = from_s.read(buf)) {
    			to_s.write(buf, 0, bytesRead);
    		}
    		
    		to_s.getFD().sync();
    		
    	} catch (IOException ioe) {
    		return false;
    	} finally {
    		if (from_s != null) {
    			try {
    	    		from_s.close();
    	    		from_s = null;
    			} catch (IOException ioe) {
    				
    			}
    		}
    		if (to_s != null) {
    			try {
    	    		to_s.close();
    	    		to_s = null;
    			} catch (IOException ioe) {
    				}
    			}
    	}
    	
    	return true;
    }
}