ThreadLocal之两则应用场景

ThreadLocal之两则应用场景

应用场景两则

• 1、利用ThreadLocal管理登录用户信息实现随用随取
• 2、可以记录Controller各个请求的执行时间

场景1spring boot实现步骤：

• 1、新建实现WebMvcConfigurerAdapter的类，重写addInterceptors方法，registry添加实现了HandlerInterceptorAdapter类的拦截器，
  同时设置需要拦截与不需要拦截的路径正则表达式；
• 2、在拦截器类中从session中取出用户信息，存入ThreadLocal中；
• 3、引入spring-boot-starter-aop依赖，设置切入点(Pointcut)为controller中的各个方法，在AOP的后置最终通知(@After)中删除ThreadLocal中的信息
  注意：当然需要在登录时将登录用户信息存入session中

代码如下：

package com.yc.aop;

import com.yc.controller.UserController;
import com.yc.entity.UserEntity;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

/**
 * @author Yue Chang
 * @version 1.0
 * @className: UserEntityAspect
 * @description: 用户信息设置切面类
 * @date 2018年06月21日 19:27
 */
@Aspect
@Component
public class UserEntityAspect {

    private static Logger logger = LoggerFactory.getLogger(UserEntityAspect.class);

    private static ThreadLocal<UserEntity> threadLocal = new ThreadLocal<>();

    @Pointcut("execution(public * com.yc.controller.*.*(..))")
    public void userEntityPointcut(){}

    @Before("userEntityPointcut()")
    public void doBefore(JoinPoint joinPoint) throws Throwable {
        // 接收到请求
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        // 从session里面获取对应的用户信息，设置到ThreadLocal中
        Object object = request.getSession().getAttribute(UserController.USER_SESSION_KEY);
        if (null != object && object instanceof UserEntity) {
            UserEntity userEntity = (UserEntity) object;
            threadLocal.set(userEntity);
        }

    }

    @After(value = "userEntityPointcut()")
    public void doAfter() throws Throwable {

        // 访问结束，清除ThreadLocal中的值，避免产生OOM
        threadLocal.remove();
    }

    /**
     * 获取ThreadLocal中的用户信息
     */
    public static UserEntity getUserEntity() {
        return threadLocal.get();
    }
}

场景2spring boot实现步骤：

• 1、引入spring-boot-starter-aop依赖，设置切入点(Pointcut)为controller中的各个方法；
• 2、在前通知中(@Before)中把调用开始时间设置到ThreadLocal中；
• 3、在后置最终通知(@After)中获得调用时间信息并删除ThreadLocal中的信息

代码如下：

package com.yc.aop;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import java.util.Arrays;

/**
 * @author Yue Chang
 * @version 1.0
 * @className: UserEntityAspect
 * @description: 时间记录切面类
 * @date 2018年06月21日 19:27
 */
@Aspect
@Component
public class VisitTimeAspect {

    private static Logger logger = LoggerFactory.getLogger(VisitTimeAspect.class);

    private static ThreadLocal<Long> threadLocal = new ThreadLocal<Long>(){
        // 设置初始值
        @Override
        protected Long initialValue() {
            return System.currentTimeMillis();
        }
    };

    @Pointcut("execution(public * com.yc.controller.*.*(..))")
    public void visitTimePointcut(){}

    @Before("visitTimePointcut()")
    public void doBefore() throws Throwable {
        // 设置开始访问时间
        threadLocal.set(System.currentTimeMillis());
    }

    @After(value = "visitTimePointcut()")
    public void doAfter(JoinPoint joinPoint) throws Throwable {

        try {
            // 接收到请求，记录请求内容
            ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
            HttpServletRequest request = attributes.getRequest();

            // 获得请求开始系统时间
            Long startTime = threadLocal.get();
            // 计算访问时间
            double second = (System.currentTimeMillis() - startTime) / 1000.0;

            // 记录下请求内容
            logger.info("URL : " + request.getRequestURL().toString() + ", cost : " + second + "s ");
            logger.info("HTTP_METHOD : " + request.getMethod());
            logger.info("IP : " + request.getRemoteAddr());
            logger.info("CLASS_METHOD : " + joinPoint.getSignature().getDeclaringTypeName() + "." + joinPoint.getSignature().getName());
            logger.info("ARGS : " + Arrays.toString(joinPoint.getArgs()));
        } finally {
            // 访问结束，清除ThreadLocal中的值，避免产生OOM
            threadLocal.remove();
        }
    }
}