private SecretKey geneKey() throws Exception { 
  //获取一个密钥生成器实例 
  KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM); 
  SecureRandom random = new SecureRandom(); 
  random.setSeed("123456".getBytes());//设置加密用的种子，密钥 
  keyGenerator.init(random); 
  SecretKey secretKey = keyGenerator.generateKey(); 
  return secretKey; 
} 

private SecretKey geneKey() throws Exception { 
  //获取一个密钥生成器实例 
  KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM); 
  SecureRandom random = new SecureRandom(); 
  keyGenerator.init(random); 
  SecretKey secretKey = keyGenerator.generateKey(); 
  return secretKey; 
} 

private SecretKey geneKey() throws Exception { 
  //获取一个密钥生成器实例 
  KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM); 
  keyGenerator.init(128); 
  SecretKey secretKey = keyGenerator.generateKey(); 
  return secretKey; 
} 

//把上面的密钥存起来 
Path keyPath = Paths.get("D:/aes.key"); 
Files.write(keyPath, secretKey.getEncoded()); 

private SecretKey readKey(Path keyPath) throws Exception { 
  //读取存起来的密钥 
  byte[] keyBytes = Files.readAllBytes(keyPath); 
  SecretKeySpec keySpec = new SecretKeySpec(keyBytes, ALGORITHM); 
  return keySpec; 
} 

Cipher cipher = Cipher.getInstance(ALGORITHM);//算法是AES 

SecretKey secretKey = this.geneKey(); 

cipher.init(Cipher.ENCRYPT_MODE, secretKey); 

cipher.update(content.getBytes()); 

byte[] result = cipher.doFinal();//加密后的字节数组 

byte[] result = cipher.doFinal(content.getBytes()); 

public class AESTest { 
 
  private static final String ALGORITHM = "AES"; 
   
  /** 
   * 生成密钥 
   * @return 
   * @throws Exception 
   */ 
  private SecretKey geneKey() throws Exception { 
    //获取一个密钥生成器实例 
    KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM); 
    SecureRandom random = new SecureRandom(); 
    random.setSeed("123456".getBytes());//设置加密用的种子，密钥 
    keyGenerator.init(random); 
    SecretKey secretKey = keyGenerator.generateKey(); 
    //把上面的密钥存起来 
    Path keyPath = Paths.get("D:/aes.key"); 
    Files.write(keyPath, secretKey.getEncoded()); 
    return secretKey; 
  } 
   
  /** 
   * 读取存储的密钥 
   * @param keyPath 
   * @return 
   * @throws Exception 
   */ 
  private SecretKey readKey(Path keyPath) throws Exception { 
    //读取存起来的密钥 
    byte[] keyBytes = Files.readAllBytes(keyPath); 
    SecretKeySpec keySpec = new SecretKeySpec(keyBytes, ALGORITHM); 
    return keySpec; 
  } 
   
  /** 
   * 加密测试 
   */ 
  @Test 
  public void testEncrypt() throws Exception { 
    //1、指定算法、获取Cipher对象 
    Cipher cipher = Cipher.getInstance(ALGORITHM);//算法是AES 
    //2、生成/读取用于加解密的密钥 
    SecretKey secretKey = this.geneKey(); 
    //3、用指定的密钥初始化Cipher对象，指定是加密模式，还是解密模式 
    cipher.init(Cipher.ENCRYPT_MODE, secretKey); 
    String content = "Hello AES";//需要加密的内容 
    //4、更新需要加密的内容 
    cipher.update(content.getBytes()); 
    //5、进行最终的加解密操作 
    byte[] result = cipher.doFinal();//加密后的字节数组 
    //也可以把4、5步组合到一起，但是如果保留了4步，同时又是如下这样使用的话，加密的内容将是之前update传递的内容和doFinal传递的内容的和。 
//   byte[] result = cipher.doFinal(content.getBytes()); 
    String base64Result = Base64.getEncoder().encodeToString(result);//对加密后的字节数组进行Base64编码 
    System.out.println("Result: " + base64Result); 
  } 
   
  /** 
   * 解密测试 
   */ 
  @Test 
  public void testDecrpyt() throws Exception { 
    Cipher cipher = Cipher.getInstance(ALGORITHM); 
    SecretKey secretKey = this.geneKey(); 
    cipher.init(Cipher.DECRYPT_MODE, secretKey); 
    String content = "pK9Xw4zqTMXYraDadSGJE3x/ftrDxIg2AM/acq0uixA=";//经过Base64加密的待解密的内容 
    byte[] encodedBytes = Base64.getDecoder().decode(content.getBytes()); 
    byte[] result = cipher.doFinal(encodedBytes);//对加密后的字节数组进行解密 
    System.out.println("Result: " + new String(result)); 
  } 
   
} 

@Test 
public void test() throws Exception { 
  Cipher cipher = Cipher.getInstance(ALGORITHM); 
  KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM); 
  keyGenerator.init(128); 
  SecretKey secretKey = keyGenerator.generateKey(); 
  //把上面的密钥存起来 
  Path keyPath = Paths.get("D:/aes.key"); 
  Files.write(keyPath, secretKey.getEncoded()); 
   
  //读取存起来的密钥 
  SecretKey key = this.readKey(keyPath); 
  cipher.init(Cipher.ENCRYPT_MODE, key); 
  cipher.update("Hello World".getBytes()); 
  //密文 
  byte[] encryptBytes = cipher.doFinal(); 
  System.out.println(Base64.getEncoder().encodeToString(encryptBytes)); 
   
  //用取出来的密钥进行解密 
  cipher.init(Cipher.DECRYPT_MODE, key); 
  //明文 
  byte[] decryptBytes = cipher.doFinal(encryptBytes); 
  System.out.println(new String(decryptBytes)); 
}