如何通过AES自定义注解的方式实现用户信息加密

要通过AES自定义注解的方式在Spring Boot中实现用户信息加密，你可以按照以下步骤操作：

1. **编写自定义注解**[^1]：
创建一个名为`@Encrypt`的自定义注解，定义必要的属性，如密钥（key）、加密算法等。示例代码可能如下：

   @Retention(RetentionPolicy.RUNTIME)
   @Target(ElementType.METHOD)
   public @interface Encrypt {
       String key() default "your_secret_key";
       // 其他加密参数可选...
   }

2. **AES加密工具类**:
设计一个工具类，比如`EncryptionUtil.java`，用于封装AES加密和解密的方法。这里可以使用Java Cryptography Extension (JCE)库来实现AES加密/解密。例如：

   import javax.crypto.Cipher;
   import java.security.Key;
   ...
   public class EncryptionUtil {
       private static final String ALGORITHM = "AES";

       // 加密方法
       public static String encrypt(String data, String key) throws Exception {
           Cipher cipher = Cipher.getInstance(ALGORITHM);
           cipher.init(Cipher.ENCRYPT_MODE, generateKey(key));
           return Base64.getEncoder().encodeToString(cipher.doFinal(data.getBytes()));
       }

       // 解密方法
       public static String decrypt(String encryptedData, String key) throws Exception {
           Cipher cipher = Cipher.getInstance(ALGORITHM);
           cipher.init(Cipher.DECRYPT_MODE, generateKey(key));
           byte[] decodedBytes = Base64.getDecoder().decode(encryptedData);
           return new String(cipher.doFinal(decodedBytes), StandardCharsets.UTF_8);
       }

       // 生成AES Key
       private static Key generateKey(String keyStr) throws Exception {
           byte[] keyBytes = keyStr.getBytes(StandardCharsets.UTF_8);
           SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, ALGORITHM);
           return secretKeySpec;
       }
   }

3. **实现ResponseBodyAdvice接口**：
创建一个实现了`ResponseBodyAdvice`接口的类，该类会在HTTP响应发送之前对结果进行处理。在这里，检测是否有`@Encrypt`注解并调用`EncryptionUtil`进行加密。示例代码：

   import org.springframework.http.ResponseEntity;
   import org.springframework.web.bind.annotation.RestControllerAdvice;
   ...
   @RestControllerAdvice
   public class ResponseBodyEncryptingAdvice implements ResponseBodyAdvice<String> {

       @Override
       public boolean supports(Class<? extends ResponseEntity<?>> responseEntityClass,
                               Method method, Object handler, HttpHeaders headers) {
           return Encrypt.class.isAnnotationPresent(method.getDeclaringClass());
       }

       @Override
       public String beforeBodyWrite(String body, MediaType mediaType, 
                                      Class<? extends ResponseEntity<?>> responseEntityClass, 
                                      Method method, Object handler, HttpHeaders headers, HttpStatus status) 
           throws IOException {
           if (body != null && method.isAnnotationPresent(Encrypt.class)) {
               String key = ((Encrypt) method.getAnnotation(Encrypt)).key();
               try {
                   return EncryptionUtil.encrypt(body, key);
               } catch (Exception e) {
                   throw new RuntimeException("Error while encrypting", e);
               }
           }
           return body;
       }
   }

4. **测试**:
在控制器方法上应用`@Encrypt`注解，然后使用测试工具（如Postman）发送请求到该接口，验证返回的响应体是否已加密。