拦截器

拦截器分同步拦截器和异步拦截器；

HandlerInterceptor

方法和执行时机

可以看DispathcerServlet的原来确定它的三个方法的执行时机；

AsynHandlerInterceptor

看注释，主要用来清理在并发环境加清理ThreadLocal的数据；

ResponseBodyAdvice

对返回值备注了@ResponseBody或者返回ResponseEntity做了一些加工；

会在使用消息转换器转换为json数据之前进行数据转换输出；

package com.springbootpractice.interceptor.config;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.ObjectMapper;import com.springbootpractice.interceptor.config.interceptor.MyInterceptor;import lombok.SneakyThrows;import org.springframework.context.annotation.Configuration;import org.springframework.core.MethodParameter;import org.springframework.http.HttpStatus;import org.springframework.http.MediaType;import org.springframework.http.ResponseEntity;import org.springframework.http.server.ServerHttpRequest;import org.springframework.http.server.ServerHttpResponse;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;import java.util.HashMap;import java.util.Map;/** * 说明：配置拦截器和设置统一返回格式 * @author carter * 创建时间： 2020年02月19日 11:03 下午 **/@Configuration@ControllerAdvicepublic class WebConfig implements WebMvcConfigurer, ResponseBodyAdvice {    @Override    public void addInterceptors(InterceptorRegistry registry) {        HandlerInterceptor myIntercepter = new MyInterceptor() ;        registry.addInterceptor(myIntercepter).addPathPatterns("/**");    }    @Override    public boolean supports(MethodParameter returnType, Class converterType) {        return true;    }    @SneakyThrows    @Override    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {       Map
   
     map = new HashMap();       map.put("result","true");       map.put("data",body);       return new ObjectMapper().writeValueAsString(map);    }}