Java中File,byte[],Object间的转换

一、有两点需要注意：

    1、Object 对象必须是可序列化对象 。


    2、可序列化的 Object 对象都可以转换为一个磁盘文件；反过来则不一定成立，只有序列
         化文件才可以转换为 Object 对象。


二、相关的转换方法

import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Byte_File_Object ...{

    /** *//**
     * 文件转化为字节数组
     * @Author Sean.guo
     * @EditTime 2007-8-13 上午11:45:28
     */
    public static byte[] getBytesFromFile(File f) ...{
        if (f == null) ...{
            return null;
        }
        try ...{
            FileInputStream stream = new FileInputStream(f);
            ByteArrayOutputStream out = new ByteArrayOutputStream(1000);
            byte[] b = new byte[1000];
            int n;
            while ((n = stream.read(b)) != -1)
                out.write(b, 0, n);
            stream.close();
            out.close();
            return out.toByteArray();
        } catch (IOException e) ...{
        }
        return null;
    }

    /** *//**
     * 把字节数组保存为一个文件
     * @Author Sean.guo
     * @EditTime 2007-8-13 上午11:45:56
     */
    public static File getFileFromBytes(byte[] b, String outputFile) ...{
        BufferedOutputStream stream = null;
        File file = null;
        try ...{
            file = new File(outputFile);
            FileOutputStream fstream = new FileOutputStream(file);
            stream = new BufferedOutputStream(fstream);
            stream.write(b);
        } catch (Exception e) ...{
            e.printStackTrace();
        } finally ...{
            if (stream != null) ...{
                try ...{
                    stream.close();
                } catch (IOException e1) ...{
                    e1.printStackTrace();
                }
            }
        }
        return file;
    }

    /** *//**
     * 从字节数组获取对象
     * @Author Sean.guo
     * @EditTime 2007-8-13 上午11:46:34
     */
    public static Object getObjectFromBytes(byte[] objBytes) throws Exception ...{
        if (objBytes == null || objBytes.length == 0) ...{
            return null;
        }
        ByteArrayInputStream bi = new ByteArrayInputStream(objBytes);
        ObjectInputStream oi = new ObjectInputStream(bi);
        return oi.readObject();
    }

    /** *//**
     * 从对象获取一个字节数组
     * @Author Sean.guo
     * @EditTime 2007-8-13 上午11:46:56
     */
    public static byte[] getBytesFromObject(Serializable obj) throws Exception ...{
        if (obj == null) ...{
            return null;
        }
        ByteArrayOutputStream bo = new ByteArrayOutputStream();
        ObjectOutputStream oo = new ObjectOutputStream(bo);
        oo.writeObject(obj);
        return bo.toByteArray();
    }

}