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问题描述：
使用 JSON 接收前端参数时，SpringMVC 默认输出日志如下：
o.s.web.servlet.DispatcherServlet : POST “/example_project/app/login”, parameters={}parameters={} 无法打印出 JSON 消息内容。
如果自己实现参数打印，则需要从 reqeust.getInputStream 中获取 JSON 内容，但是由于流只能读取一次，所以会导致后续 SpringMVC 解析参数异常。网上找到一种比较解决方法：用 HttpRequestWrapper 重新封装 Reqeust，使打印日志后 SpringMVC 能正常解析 HttpReqeust。这种方法比较麻烦, 这里不去研究
这里主要说说 Spring 提供的较好的解决方案：
可以通过自定义 RequestBodyAdvisor、ResponseBodyAdvisor 来实现日志输出。
RequestBodyAdvisor 可以获取到解析后的 Controller 方法参数对象。
ResponseBodyAdvisor 可以获取到 Controller 方法返回值对象。
然后将他们注册到 requestMappingHandlerAdapter：
// 继承 WebMvcConfigurationSupport，重写该方法
@Override
@Bean
public RequestMappingHandlerAdapter requestMappingHandlerAdapter() {
RequestMappingHandlerAdapter adapter = super.requestMappingHandlerAdapter();
adapter.setRequestBodyAdvice(Lists.newArrayList(new CustomerRequestBodyAdvisor()));
adapter.setResponseBodyAdvice(Lists.newArrayList(new CustomerResponseBodyAdvisor()));
return adapter;
}
另附 CustomerRequestBodyAdvisor、CustomerResponseBodyAdvisor 日志输出实现参考:
RequestBodyAdvisor 实现参考：
// CustomerRequestBodyAdvisor.java
/**
* 打印请求参数日志
*/
public class CustomerRequestBodyAdvisor extends RequestBodyAdviceAdapter {
private static final Logger logger = LoggerFactory.getLogger(CustomerRequestBodyAdvisor.class);
@Override
public boolean supports(MethodParameter methodParameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
// 只处理 @RequestBody 注解了的参数
return methodParameter.getParameterAnnotation(RequestBody.class) != null;
}
@Override
public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
Method method = parameter.getMethod();
// 参数对象转 JSON 字符串
String jsonBody;
if (StringHttpMessageConverter.class.isAssignableFrom(converterType)) {
jsonBody = body.toString();
} else {
jsonBody = JSON.toJSONString(body, SerializerFeature.UseSingleQuotes);
}
// 自定义日志输出
if (logger.isInfoEnabled()) {
logger.info(“{}#{}: {}”, parameter.getContainingClass().getSimpleName(), method.getName(), jsonBody);
// logger.info(“json request<=========method:{}#{}”, parameter.getContainingClass().getSimpleName(), method.getName());
}
return super.afterBodyRead(body, inputMessage, parameter, targetType, converterType);
}
}
ResponseBodyAdvisor 实现参考:
// CustomerResponseBodyAdvisor.java
/**
* 打印响应值日志
*/
public class CustomerResponseBodyAdvisor implements ResponseBodyAdvice<Object> {
private static final Logger logger = LoggerFactory.getLogger(CustomerResponseBodyAdvisor.class);
@Override
public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
return AbstractJackson2HttpMessageConverter.class.isAssignableFrom(converterType)
|| returnType.getMethod().isAnnotationPresent(ResponseBody.class);
}
@Override
public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
// 响应值转 JSON 串输出到日志系统
if (logger.isInfoEnabled()) {
logger.info(“{}: {}”, request.getURI(), JSON.toJSONString(body, SerializerFeature.UseSingleQuotes));
}
return body;
}
}