Java中File,byte[],Object間的轉換
阿新 • • 發佈：2018-11-16
部落格分類：
java基礎及框架
java
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.ObjectInputStream;
import
java.io.ObjectOutputStream;
import
java.io.Serializable;
public
class
Byte_File_Object
...
{
/** */
* 檔案轉化為位元組陣列
* @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];
for (int n;(n = stream.read(b)) != -1;) {
stream.close();
out.close();
return out.toByteArray();
} catch (IOException e) ...{
}
return null;
}
/** *//**
* 把位元組陣列儲存為一個檔案
* @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;
}
/** *//**
* 從位元組陣列獲取物件
* @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();
}
/** *//**
* 從物件獲取一個位元組陣列
* @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();
}
}
一、有兩點需要注意：
1、Object 物件必須是可序列化物件 。
2、可序列化的 Object 物件都可以轉換為一個磁碟檔案；反過來則不一定成立，只有序列
化檔案才可以轉換為 Object 物件。
二、相關的轉換方法：
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.ObjectInputStream;
import
java.io.ObjectOutputStream;
import
java.io.Serializable;
public
class
Byte_File_Object
...
{ /** */ * 檔案轉化為位元組陣列 * @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]; for (int n;(n = stream.read(b)) != -1;) {out.write(b, 0, n);}
stream.close(); out.close(); return out.toByteArray(); } catch (IOException e) ...{ } return null; } /** *//** * 把位元組陣列儲存為一個檔案 * @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; } /** *//** * 從位元組陣列獲取物件 * @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(); } /** *//** * 從物件獲取一個位元組陣列 * @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(); }}