1. 利用拦截器实现记录日志功能

1.1 需要有web依赖，pom.xml中进行配置

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
</dependency>

1.2 自定义MyLog注解

package com.example.log;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyLog {
    /**
     * 方法描述
     */
    String desc() default "";
}

1.3 自定义日志拦截器MyLogInterceptor

package com.example.interceptor;

import com.example.log.MyLog;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

public class MyLogInterceptor implements HandlerInterceptor {

    private static final ThreadLocal<Long> startTimeThreadLocal = new ThreadLocal<>();

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HandlerMethod handlerMethod = (HandlerMethod)handler;
        Method method = handlerMethod.getMethod();//获得被拦截的方法对象
        MyLog myLog = method.getAnnotation(MyLog.class);//获得方法上的注解
        if(myLog != null){
            //方法上加了MyLog注解，需要进行日志记录
            long startTime = System.currentTimeMillis();
            startTimeThreadLocal.set(startTime);
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerMethod handlerMethod = (HandlerMethod)handler;
        Method method = handlerMethod.getMethod();//获得被拦截的方法对象
        MyLog myLog = method.getAnnotation(MyLog.class);//获得方法上的注解
        if(myLog != null){
            //方法上加了MyLog注解，需要进行日志记录
            long endTime = System.currentTimeMillis();
            Long startTime = startTimeThreadLocal.get();
            long optTime = endTime - startTime;

            String requestUri = request.getRequestURI();
            String methodName = method.getDeclaringClass().getName() + "." +
                    method.getName();
            String methodDesc = myLog.desc();

            System.out.println("请求uri：" + requestUri);
            System.out.println("请求方法名：" + methodName);
            System.out.println("方法描述：" + methodDesc);
            System.out.println("方法执行时间：" + optTime + "ms");
        }
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

1.4 创建自动配置类MyLogAutoConfiguration

package com.example.config;

import com.example.interceptor.MyLogInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyLogAutoConfiguration implements WebMvcConfigurer {
    //注册自定义日志拦截器
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyLogInterceptor())
                .addPathPatterns("/**")                     // 配置拦截路径
                .excludePathPatterns("/static/**");         // 配置哪些路径不进行拦截
    }
}

• 这是一个配置类，且需要实现webMvcConfigurer，用于向mvc容器中添加组件

 1.5 在controller中的方法上添加@MyLog注解

package com.example.controller;
import com.example.log.MyLog;
import com.example.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/hello")
public class HelloController {
    //HelloService在我们自定义的starter中已经完成了自动配置，所以此处可以直接注入
    @Autowired
    private HelloService helloService;

    @MyLog(desc = "sayHello方法") //日志记录注解
    @GetMapping("/say")
    public String sayHello(){
        return helloService.sayHello();
    }
}

 至此，拦截器配置完成，且可以使用了。