转转转--Java File和byte数据之间的转换

package cn.iworker.file;  

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

public class FileTest
{  

    public static void main(String[] args)
    {
        file2BetyArray();
        fileToBetyArray();
        BetyToFile("D:\\Study\\Java\\First.class");
    }  

    public static byte[] file2BetyArray()
    {
        File file = new File("D:\\Study\\Java\\First.class");
        if (!file.exists()) {
            return null;
        }
        FileInputStream stream = null;
        ByteArrayOutputStream out = null;
        try {
            stream = new FileInputStream(file);
            out = new ByteArrayOutputStream(1000);
            byte[] b = new byte[1000];
            int n;
            while ((n = stream.read(b)) != -1) {
                out.write(b, 0, n);
            }
            return out.toByteArray();// 此方法大文件OutOfMemory
        } catch (Exception e) {
            System.out.println(e.toString());
        } finally {
            try {
                stream.close();
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }  

        }
        return null;
    }  

    public static byte[] fileToBetyArray()
    {
        FileInputStream fileInputStream = null;
        File file = new File("D:\\Study\\Java\\First.class");
        byte[] bFile = null;
        try {
            bFile = new byte[(int) file.length()];
            fileInputStream = new FileInputStream(file);
            fileInputStream.read(bFile);
            fileInputStream.close();
            for (int i = 0; i < bFile.length; i++) {
                System.out.print((char) bFile[i]);
            }
            System.out.println("Done");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                fileInputStream.close();
                bFile.clone();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return bFile;
    }  

    public  static File BetyToFile( String filePath)
    {
        File file = new File(filePath);
        BufferedOutputStream stream = null;
        FileOutputStream fstream = null;
        byte[] data=new byte[(int)file.length()];
        try {
            fstream = new FileOutputStream(file);
            stream = new BufferedOutputStream(fstream);
            stream.write(data);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (stream != null) {
                    stream.close();
                }
                if (null != fstream) {
                    fstream.close();
                }
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
        return file;
    }  

}  

public static void byte2File(byte[] buf, 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 + File.separator + fileName);
            fos = new FileOutputStream(file);
            bos = new BufferedOutputStream(fos);
            bos.write(buf);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (bos != null)
            {
                try
                {
                    bos.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            if (fos != null)
            {
                try
                {
                    fos.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
    }