Java中File,byte[],Object间的转换

雨点打透心脏的1/2处 2022-07-13 02:41 507阅读 0赞

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：

![None.gif][] import  java.io.BufferedOutputStream;  
![None.gif][] import  java.io.ByteArrayInputStream;  
![None.gif][] import  java.io.ByteArrayOutputStream;  
![None.gif][] import  java.io.File;  
![None.gif][] import  java.io.FileInputStream;  
![None.gif][] import  java.io.FileOutputStream;  
![None.gif][] import  java.io.IOException;  
![None.gif][] import  java.io.ObjectInputStream;  
![None.gif][] import  java.io.ObjectOutputStream;  
![None.gif][] import  java.io.Serializable;  
![None.gif][]  
![ExpandedBlockStart.gif][] ![ContractedBlock.gif][] public   class  Byte\_File\_Object  ... \{  
![InBlock.gif][]  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      /\*\* \*/ /\*\*   
![InBlock.gif][]      \* 文件转化为字节数组  
![InBlock.gif][]      \* @Author Sean.guo  
![InBlock.gif][]      \* @EditTime 2007-8-13 上午11:45:28  
![ExpandedSubBlockEnd.gif][]       \*/   
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      public   static   byte \[\] getBytesFromFile(File f)  ... \{  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]          if  (f  ==   null )  ... \{  
![InBlock.gif][]              return   null ;  
![ExpandedSubBlockEnd.gif][]         \}   
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]          try   ... \{  
![InBlock.gif][]             FileInputStream stream  =   new  FileInputStream(f);  
![InBlock.gif][]             ByteArrayOutputStream out  =   new  ByteArrayOutputStream( 1000 );  
![InBlock.gif][]              byte \[\] b  =   new   byte \[ 1000 \];  
![InBlock.gif][]              int  n;  
![InBlock.gif][]              while  ((n  =  stream.read(b))  !=   \- 1 )  
![InBlock.gif][]                 out.write(b,  0 , n);  
![InBlock.gif][]             stream.close();  
![InBlock.gif][]             out.close();  
![InBlock.gif][]              return  out.toByteArray();  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]         \}   catch  (IOException e)  ... \{  
![ExpandedSubBlockEnd.gif][]         \}   
![InBlock.gif][]          return   null ;  
![ExpandedSubBlockEnd.gif][]     \}   
![InBlock.gif][]  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      /\*\* \*/ /\*\*   
![InBlock.gif][]      \* 把字节数组保存为一个文件  
![InBlock.gif][]      \* @Author Sean.guo  
![InBlock.gif][]      \* @EditTime 2007-8-13 上午11:45:56  
![ExpandedSubBlockEnd.gif][]       \*/   
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      public   static  File getFileFromBytes( byte \[\] b, String outputFile)  ... \{  
![InBlock.gif][]         BufferedOutputStream stream  =   null ;  
![InBlock.gif][]         File file  =   null ;  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]          try   ... \{  
![InBlock.gif][]             file  =   new  File(outputFile);  
![InBlock.gif][]             FileOutputStream fstream  =   new  FileOutputStream(file);  
![InBlock.gif][]             stream  =   new  BufferedOutputStream(fstream);  
![InBlock.gif][]             stream.write(b);  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]         \}   catch  (Exception e)  ... \{  
![InBlock.gif][]             e.printStackTrace();  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]         \}   finally   ... \{  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]              if  (stream  !=   null )  ... \{  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]                  try   ... \{  
![InBlock.gif][]                     stream.close();  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]                 \}   catch  (IOException e1)  ... \{  
![InBlock.gif][]                     e1.printStackTrace();  
![ExpandedSubBlockEnd.gif][]                 \}   
![ExpandedSubBlockEnd.gif][]             \}   
![ExpandedSubBlockEnd.gif][]         \}   
![InBlock.gif][]          return  file;  
![ExpandedSubBlockEnd.gif][]     \}   
![InBlock.gif][]  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      /\*\* \*/ /\*\*   
![InBlock.gif][]      \* 从字节数组获取对象  
![InBlock.gif][]      \* @Author Sean.guo  
![InBlock.gif][]      \* @EditTime 2007-8-13 上午11:46:34  
![ExpandedSubBlockEnd.gif][]       \*/   
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      public   static  Object getObjectFromBytes( byte \[\] objBytes)  throws  Exception  ... \{  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]          if  (objBytes  ==   null   ||  objBytes.length  ==   0 )  ... \{  
![InBlock.gif][]              return   null ;  
![ExpandedSubBlockEnd.gif][]         \}   
![InBlock.gif][]         ByteArrayInputStream bi  =   new  ByteArrayInputStream(objBytes);  
![InBlock.gif][]         ObjectInputStream oi  =   new  ObjectInputStream(bi);  
![InBlock.gif][]          return  oi.readObject();  
![ExpandedSubBlockEnd.gif][]     \}   
![InBlock.gif][]  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      /\*\* \*/ /\*\*   
![InBlock.gif][]      \* 从对象获取一个字节数组  
![InBlock.gif][]      \* @Author Sean.guo  
![InBlock.gif][]      \* @EditTime 2007-8-13 上午11:46:56  
![ExpandedSubBlockEnd.gif][]       \*/   
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]      public   static   byte \[\] getBytesFromObject(Serializable obj)  throws  Exception  ... \{  
![ExpandedSubBlockStart.gif][] ![ContractedSubBlock.gif][]          if  (obj  ==   null )  ... \{  
![InBlock.gif][]              return   null ;  
![ExpandedSubBlockEnd.gif][]         \}   
![InBlock.gif][]         ByteArrayOutputStream bo  =   new  ByteArrayOutputStream();  
![InBlock.gif][]         ObjectOutputStream oo  =   new  ObjectOutputStream(bo);  
![InBlock.gif][]         oo.writeObject(obj);  
![InBlock.gif][]          return  bo.toByteArray();  
![ExpandedSubBlockEnd.gif][]     \}   
![InBlock.gif][]  
![ExpandedBlockEnd.gif][] \}

[None.gif]: /images/20220713/b652d81fff744c1788d72d80870e8474.png
[ExpandedBlockStart.gif]: http://images.csdn.net/syntaxhighlighting/OutliningIndicators/ExpandedBlockStart.gif
[ContractedBlock.gif]: /images/20220713/192cd39d86874d31b34fbb769ebbfc9b.png
[InBlock.gif]: /images/20220713/b0622ba0a36b49fc9ce06aaf97675d05.png
[ExpandedSubBlockStart.gif]: http://images.csdn.net/syntaxhighlighting/OutliningIndicators/ExpandedSubBlockStart.gif
[ContractedSubBlock.gif]: /images/20220713/754d25031e1e4ca69167e91364f1da92.png
[ExpandedSubBlockEnd.gif]: /images/20220713/2b83e018657b47f295759ce3008f1a79.png
[ExpandedBlockEnd.gif]: /images/20220713/b219a95e0b3d4e898c060b898058341f.png