Java 对象加密解密

import   java.io.*; 

import   javax.crypto.*; 
import   java.security.*; 

class   A 
        implements   Serializable   { 
        private   String   a; 
        public   String   getA()   { 
                return   a; 
        } 

        public   void   setA(String   a)   { 
                this.a   =   a; 
        } 
        public   String   toString(){ 
                return   a; 
        } 
} 

public   class   DESObjectToFile   { 
        public   static   void   main(String[]   args)   { 
                KeyGenerator   kg   =   null; 
                try   { 
                        //指定算法,这里为DES 
                        kg   =   KeyGenerator.getInstance( "DES ",   "SunJCE "); 

                        //指定密钥长度,长度越高,加密强度越大 
                        kg.init(56); 

                        //产生密钥 
                        Key   key   =   kg.generateKey(); 

                        //记得把密钥保存起来 
                        String   keyfilename= "d:\\key.dat "; 
                        
                        ObjectOutputStream   out   =   new   ObjectOutputStream(new 
                                BufferedOutputStream(new   FileOutputStream(keyfilename))); 
                        out.writeObject(key); 
                        out.close(); 

                        //加密要用Cipher来实现 
                        Cipher   cipher   =   Cipher.getInstance( "DES "); 

                        String   filename   =   "d:\\加密的对象.dat "; 
                        //读入并加密文件 
                        try   { 
                                //设置加密模式 
                                cipher.init(Cipher.ENCRYPT_MODE,   key); 
                                //输出流 
                                out   =   new   ObjectOutputStream(new   CipherOutputStream(new 
                                        BufferedOutputStream(new   FileOutputStream(filename)), 
                                        cipher)); 
                                A   aa   =   new   A(); 
                                aa.setA( "aaa "); 
                                out.writeObject(aa); 
                                
                                out.close(); 
                                System.out.println( "加密完成！ "); 
                        } 
                        catch   (Exception   ey5)   { 
                                System.out.println( "Error   when   encrypt   the   file "); 
                                System.exit(0); 
                        } 

                        try   { 
                                //把key从文件取出 
                                ObjectInputStream   in   =new   ObjectInputStream(new 
                                        BufferedInputStream(new   FileInputStream(keyfilename))); 
                                key=(Key)in.readObject(); 
                                in.close(); 
                                
                                //设置解密模式 
                              cipher.init(Cipher.DECRYPT_MODE,   key); 
                                //输入流 
                                in   =new   ObjectInputStream(new   CipherInputStream(new 
                                        BufferedInputStream( 
                                                new   FileInputStream(filename)),   cipher)); 

                                Object   a=in.readObject(); 
                                System.out.println(a); 
                                in.close(); 
                                
                                System.out.println( "解密完成！ "); 
                        } 
                        catch   (Exception   ey5)   { 
                                System.out.println( "Error   when   encrypt   the   file "); 
                                System.exit(0); 
                        } 
                } 
                catch   (Exception   e)   { 
                        e.printStackTrace(); 
                } 
        } 
}