Java byte配列とファイルの相互変換

package com.amc.oainterface.service;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;

/**
 *      
 * @author suyunlong
 *
 */
public class FileUtil {
	/**
	 *        byte   
	 * @param filePath       
	 * @return
	 */
	public static byte[] file2Byte(String filePath){
		ByteArrayOutputStream bos=null;
		BufferedInputStream in=null;
		try{
			File file=new File(filePath);
			if(!file.exists()){  
	            throw new FileNotFoundException("file not exists");  
	        }
			bos=new ByteArrayOutputStream((int)file.length());
			in=new BufferedInputStream(new FileInputStream(file));
			int buf_size=1024;
			byte[] buffer=new byte[buf_size];
			int len=0;
			while(-1 != (len=in.read(buffer,0,buf_size))){
				bos.write(buffer,0,len);
			}
			return bos.toByteArray();
		}
		catch(Exception e){
			System.out.println(e.getMessage());
            e.printStackTrace();
            return null;
		}
		finally{
			try{
				if(in!=null){
					in.close();
				}
				if(bos!=null){
					bos.close();
				}
            }
			catch(Exception e){
				System.out.println(e.getMessage());
				e.printStackTrace();  
            }
        }
    }
    /**
     *   byte  ，     
     * @param bfile     
     * @param filePath       
     * @param fileName     
     */
	public static void byte2File(byte[] bfile,String filePath,String fileName){
		BufferedOutputStream bos=null;
		FileOutputStream fos=null;
		File file=null;
		try{
			File dir=new File(filePath);
			if(!dir.exists() && !dir.isDirectory()){//            
				dir.mkdirs();  
            }
			file=new File(filePath+fileName);
			fos=new FileOutputStream(file);
			bos=new BufferedOutputStream(fos);
			bos.write(bfile);
		} 
		catch(Exception e){
			System.out.println(e.getMessage());
			e.printStackTrace();  
        }
		finally{
			try{
				if(bos != null){
					bos.close(); 
				}
				if(fos != null){
					fos.close();
				}
			}
			catch(Exception e){
				System.out.println(e.getMessage());
				e.printStackTrace();  
			}
		}
    }
}