生成AES密钥，网摘自留

import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class AESmiyao {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		getA221();
	}
	/**
	 * 自动生成AES128位密钥
	 */
	public static void getA221(){
		try {
			KeyGenerator kg = KeyGenerator.getInstance("AES");
			kg.init(128);//要生成多少位，只需要修改这里即可128, 192或256
			SecretKey sk = kg.generateKey();
			byte[] b = sk.getEncoded();
			String s = byteToHexString(b);
			System.out.println(s);
			System.out.println("十六进制密钥长度为"+s.length());
			System.out.println("二进制密钥的长度为"+s.length()*4);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			System.out.println("没有此算法。");
		}
	}
	
	/**
	 * 二进制byte[]转十六进制string
	 */
	public static String byteToHexString(byte[] bytes){   
	     StringBuffer sb = new StringBuffer();   
	     for (int i = 0; i < bytes.length; i++) {   
	          String strHex=Integer.toHexString(bytes[i]);   
	          if(strHex.length() > 3){   
	                 sb.append(strHex.substring(6));   
	          } else {
	               if(strHex.length() < 2){
	                  sb.append("0" + strHex);
	               } else {
	                  sb.append(strHex);   
	               }   
	          }
	     }
	    return  sb.toString();   
	}
	
	/**
	 * 十六进制string转二进制byte[]
	 */
	public static byte[] hexStringToByte(String s) {   
	    byte[] baKeyword = new byte[s.length() / 2];   
	    for (int i = 0; i < baKeyword.length; i++) {   
	        try {   
	            baKeyword[i] = (byte) (0xff & Integer.parseInt(s.substring(i * 2, i * 2 + 2), 16));   
	        } catch (Exception e) {   
	            System.out.println("十六进制转byte发生错误！！！");   
	            e.printStackTrace();   
	        }   
	    }   
	    return baKeyword;   
	} 
	
	/**
	 * 使用对称密钥进行加密
	 */
	public static void getA231() throws Exception{
		String keys = "c0e9fcff59ecc3b8b92939a1a2724a44";	//密钥
		byte[] keyb = hexStringToByte(keys);
		String mingwen = "hello word!";							//明文
		SecretKeySpec sKeySpec = new SecretKeySpec(keyb, "AES");
		Cipher cipher = Cipher.getInstance("AES");
		cipher.init(Cipher.ENCRYPT_MODE, sKeySpec);
		byte[] bjiamihou = cipher.doFinal(mingwen.getBytes());
		System.out.println(byteToHexString(bjiamihou));		//加密后数据为ecf0a6bc80dbaf657eac9b06ecd92962
	}
	
	/**
	 * 使用对称密钥进行解密 
	 */
	public static void getA232() throws Exception{
		String keys = "c0e9fcff59ecc3b8b92939a1a2724a44";	//密钥
		byte[] keyb = hexStringToByte(keys);
		String sjiami = "ecf0a6bc80dbaf657eac9b06ecd92962";	//密文
		byte[] miwen = hexStringToByte(sjiami);
		SecretKeySpec sKeySpec = new SecretKeySpec(keyb, "AES");
		Cipher cipher = Cipher.getInstance("AES");
		cipher.init(Cipher.DECRYPT_MODE, sKeySpec);
		byte[] bjiemihou = cipher.doFinal(miwen);
		System.out.println(new String(bjiemihou));
	}


}