SpringBoot实现接口数据的加解密功能

对接口的加密解密操作主要有下面两种方式：

自定义消息转换器

优势：仅需实现接口，配置简单。
劣势：仅能对同一类型的MediaType进行加解密操作，不灵活。

使用spring提供的接口RequestBodyAdvice和ResponseBodyAdvice
优势：可以按照请求的Referrer、Header或url进行判断，按照特定需要进行加密解密。

比如在一个项目升级的时候，新开发功能的接口需要加解密，老功能模块走之前的逻辑不加密，这时候就只能选择上面的第二种方式了，下面主要介绍下第二种方式加密、解密的过程。

RequestBodyAdvice可以理解为在@RequestBody之前需要进行的 操作，ResponseBodyAdvice可以理解为在@ResponseBody之后进行的操作，所以当接口需要加解密时，在使用@RequestBody接收前台参数之前可以先在RequestBodyAdvice的实现类中进行参数的解密，当操作结束需要返回数据时，可以在@ResponseBody之后进入ResponseBodyAdvice的实现类中进行参数的加密。

RequestBodyAdvice处理请求的过程：

RequestBodyAdvice源码如下：

public interface RequestBodyAdvice {
 boolean supports(MethodParameter methodParameter, Type targetType,
   Class> converterType);
 HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter,
   Type targetType, Class> converterType) throws IOException;
 Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter,
   Type targetType, Class> converterType);
 @Nullable
 Object handleEmptyBody(@Nullable Object body, HttpInputMessage inputMessage, MethodParameter parameter,
   Type targetType, Class> converterType);
}

调用RequestBodyAdvice实现类的部分代码如下：

protected  Object readWithMessageConverters(HttpInputMessage inputMessage, MethodParameter parameter,
   Type targetType) throws IOException, HttpMediaTypeNotSupportedException, HttpMessageNotReadableException {
  MediaType contentType;
  boolean noContentType = false;
  try {
   contentType = inputMessage.getHeaders().getContentType();
  }
  catch (InvalidMediaTypeException ex) {
   throw new HttpMediaTypeNotSupportedException(ex.getMessage());
  }
  if (contentType == null) {
   noContentType = true;
   contentType = MediaType.APPLICATION_OCTET_STREAM;
  }
  Class contextClass = parameter.getContainingClass();
  Class targetClass = (targetType instanceof Class ? (Class) targetType : null);
  if (targetClass == null) {
   ResolvableType resolvableType = ResolvableType.forMethodParameter(parameter);
   targetClass = (Class) resolvableType.resolve();
  }
  HttpMethod httpMethod = (inputMessage instanceof HttpRequest ? ((HttpRequest) inputMessage).getMethod() : null);
  Object body = NO_VALUE;
  EmptyBodyCheckingHttpInputMessage message;
  try {
   message = new EmptyBodyCheckingHttpInputMessage(inputMessage);
   for (HttpMessageConverter converter : this.messageConverters) {
    Class> converterType = (Class>) converter.getClass();
    GenericHttpMessageConverter genericConverter =
      (converter instanceof GenericHttpMessageConverter ? (GenericHttpMessageConverter) converter : null);
    if (genericConverter != null ? genericConverter.canRead(targetType, contextClass, contentType) :
      (targetClass != null && converter.canRead(targetClass, contentType))) {
     if (logger.isDebugEnabled()) {
      logger.debug("Read [" + targetType + "] as "" + contentType + "" with [" + converter + "]");
     }
     if (message.hasBody()) {
      HttpInputMessage msgToUse =
 getAdvice().beforeBodyRead(message, parameter, targetType, converterType);
      body = (genericConverter != null ? genericConverter.read(targetType, contextClass, msgToUse) :
 ((HttpMessageConverter) converter).read(targetClass, msgToUse));
      body = getAdvice().afterBodyRead(body, msgToUse, parameter, targetType, converterType);
     }
     else {
      body = getAdvice().handleEmptyBody(null, message, parameter, targetType, converterType);
     }
     break;
    }
   }
  }
  catch (IOException ex) {
   throw new HttpMessageNotReadableException("I/O error while reading input message", ex);
  }
  if (body == NO_VALUE) {
   if (httpMethod == null || !SUPPORTED_METHODS.contains(httpMethod) ||
     (noContentType && !message.hasBody())) {
    return null;
   }
   throw new HttpMediaTypeNotSupportedException(contentType, this.allSupportedMediaTypes);
  }
  return body;
 }

从上面源码可以到当converter.canRead()和message.hasBody()都为true的时候，会调用beforeBodyRead()和afterBodyRead()方法，所以我们在实现类的afterBodyRead()中添加解密代码即可。

ResponseBodyAdvice处理响应的过程：

ResponseBodyAdvice源码如下：

public interface ResponseBodyAdvice {
 boolean supports(MethodParameter returnType, Class> converterType);
 @Nullable
 T beforeBodyWrite(@Nullable T body, MethodParameter returnType, MediaType selectedContentType,
   Class> selectedConverterType,
   ServerHttpRequest request, ServerHttpResponse response);
}

调用ResponseBodyAdvice实现类的部分代码如下：

if (selectedMediaType != null) {
   selectedMediaType = selectedMediaType.removeQualityValue();
   for (HttpMessageConverter converter : this.messageConverters) {
    GenericHttpMessageConverter genericConverter =
      (converter instanceof GenericHttpMessageConverter ? (GenericHttpMessageConverter) converter : null);
    if (genericConverter != null ?
      ((GenericHttpMessageConverter) converter).canWrite(declaredType, valueType, selectedMediaType) :
      converter.canWrite(valueType, selectedMediaType)) {
     outputValue = (T) getAdvice().beforeBodyWrite(outputValue, returnType, selectedMediaType,
(Class>) converter.getClass(),
inputMessage, outputMessage);
     if (outputValue != null) {
      addContentDispositionHeader(inputMessage, outputMessage);
      if (genericConverter != null) {
genericConverter.write(outputValue, declaredType, selectedMediaType, outputMessage);
      }
      else {
((HttpMessageConverter) converter).write(outputValue, selectedMediaType, outputMessage);
      }
      if (logger.isDebugEnabled()) {
logger.debug("Written [" + outputValue + "] as "" + selectedMediaType +
  "" using [" + converter + "]");
      }
     }
     return;
    }
   }
  }

从上面源码可以到当converter.canWrite()为true的时候，会调用beforeBodyWrite()方法，所以我们在实现类的beforeBodyWrite()中添加解密代码即可。

新建一个spring boot项目spring-boot-encry，按照下面步骤操作。

pom.xml中引入jar

  
   org.springframework.boot
   spring-boot-starter-web
  

  
   org.projectlombok
   lombok
   true
  
  
   org.springframework.boot
   spring-boot-starter-test
   test
   
    
     org.junit.vintage
     junit-vintage-engine
    
   
  

  
   com.alibaba
   fastjson
   1.2.60
  
 

请求参数解密拦截类

DecryptRequestBodyAdvice代码如下：

@Component
@ControllerAdvice(basePackages = "com.example.springbootencry.controller")
@Slf4j
public class DecryptRequestBodyAdvice implements RequestBodyAdvice {
 @Override
 public boolean supports(MethodParameter methodParameter, Type targetType, Class> converterType) {
  return true;
 }
 @Override
 public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter methodParameter, Type targetType, Class> selectedConverterType) throws IOException {
  return inputMessage;
 }
 @Override
 public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class> converterType) {
  String dealData = null;
  try {
   //解密操作
   Map dataMap = (Map)body;
   String srcData = dataMap.get("data");
   dealData = DesUtil.decrypt(srcData);
  } catch (Exception e) {
   log.error("异常！", e);
  }
  return dealData;
 }
 @Override
 public Object handleEmptyBody(@Nullable Object var1, HttpInputMessage var2, MethodParameter var3, Type var4, Class> var5) {
  log.info("3333");
  return var1;
 }
}

响应参数加密拦截类

EncryResponseBodyAdvice代码如下：

@Component
@ControllerAdvice(basePackages = "com.example.springbootencry.controller")
@Slf4j
public class EncryResponseBodyAdvice implements ResponseBodyAdvice