利用Java如何實現(xiàn)一個AES256加密解密功能

package com.handler;
import java.io.UnsupportedEncodingException;
import java.security.Key;
import java.security.Security;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
public class AES256Encryption{
public static final String KEY_ALGORITHM="AES";
public static final String CIPHER_ALGORITHM="AES/ECB/PKCS7Padding";
public static byte[] initkey() throws Exception{
   //實例化密鑰生成器
     Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
     KeyGenerator kg=KeyGenerator.getInstance(KEY_ALGORITHM, "BC");
     kg.init(256);
     kg.init(128);
     SecretKey secretKey=kg.generateKey();
     return secretKey.getEncoded();
}
public static byte[] initRootKey() throws Exception{
     return new byte[] { 0x08, 0x08, 0x04, 0x0b, 0x02, 0x0f, 0x0b, 0x0c,
       0x01, 0x03, 0x09, 0x07, 0x0c, 0x03, 0x07, 0x0a, 0x04, 0x0f,
        0x06, 0x0f, 0x0e, 0x09, 0x05, 0x01, 0x0a, 0x0a, 0x01, 0x09,
       0x06, 0x07, 0x09, 0x0d };
}
public static Key toKey(byte[] key) throws Exception{
SecretKey secretKey=new SecretKeySpec(key,KEY_ALGORITHM);
return secretKey;
}
public static byte[] encrypt(byte[] data,byte[] key) throws Exception{
  Key k=toKey(key);
  Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
  Cipher cipher=Cipher.getInstance(CIPHER_ALGORITHM, "BC");
  cipher.init(Cipher.ENCRYPT_MODE, k);
  return cipher.doFinal(data);
}
public static byte[] decrypt(byte[] data,byte[] key) throws Exception{
    Key k =toKey(key);
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    Cipher cipher=Cipher.getInstance(CIPHER_ALGORITHM, "BC");
    cipher.init(Cipher.DECRYPT_MODE, k);
    return cipher.doFinal(data);
}
public static void main(String[] args) throws UnsupportedEncodingException{
     String str="蕓sweet";
     //打印原文
     System.out.println("原文："+str);
     //密鑰
     byte[] key;
     try {
    //生成隨機密鑰
       key = AES256Encryption.initkey();
       //打印密鑰
       System.out.print("密鑰：");
       for(int i = 0;i
        System.out.printf("%x", key[i]);
       }
       System.out.print("n");
       //加密
       byte[] data=AES256Encryption.encrypt(str.getBytes(), key);
       //打印密文
       System.out.print("加密后：");
       for(int i = 0;i
        System.out.printf("%x", data[i]);
       }
       System.out.print("n");
       //解密密文
       data=AES256Encryption.decrypt(data, key);
       //打印原文
       System.out.println("解密后："+new String(data));
} catch (Exception e) {
  e.printStackTrace();
}