/**
 * <p>自定義RequestHolder</p></p>
 *
 * @Author zjq
 * @Date 2021/12
 */
public class RequestHolder {

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

    public static void set(Long id) {
        requestHolder.set(id);
    }

    public static Long get() {
        return requestHolder.get();
    }

    public static void remove() {
        requestHolder.remove();
    }

}

自定義過濾器

自定義定義攔截器繼承Filter接口，實現(xiàn)ThredLocal.add()方法

/**
 * <p>自定義過濾器</p>
 *
 * @Author zjq
 * @Date 2021/12/7
 */
@Slf4j
public class HttpFilter implements Filter {

    /**
     * 為Filter初始化 提供支持
     *
     * @param filterConfig
     * @throws ServletException
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    /**
     * 攔截到要執(zhí)行的請求時，doFilter就會執(zhí)行。這里我們可以寫對請求和響應(yīng)的預(yù)處理。
     * FilterChain把請求和響應(yīng)傳遞給下一個 Filter處理
     *
     * @param servletRequest
     * @param servletResponse
     * @param filterChain
     * @throws IOException
     * @throws ServletException
     */
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //把普通servlet強轉(zhuǎn)成httpServlet
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        Long threadId = Thread.currentThread().getId();
        log.info("do filter,threadId:{} servletPath:{}", threadId, httpServletRequest.getServletPath());
        //把當前線程id放入requestHolder
        RequestHolder.set(threadId);
        //放行
        filterChain.doFilter(httpServletRequest, servletResponse);
    }

    /**
     * Filter 實例銷毀前的準備工作
     */
    @Override
    public void destroy() {

    }
}

自定義攔截器

自定義攔截器在線程使用完畢后移除ThredLocal中內(nèi)容，避免內(nèi)存溢出

/**
 * <p>自定義攔截器</p>
 *
 * @Author zjq
 * @Date 2021/12/7
 */
@Slf4j
public class HttpInterceptor extends HandlerInterceptorAdapter {

    /**
     * 攔截處理程序的執(zhí)行。在 HandlerMapping 確定合適的處理程序?qū)ο笾螅?HandlerAdapter 調(diào)用處理程序之前調(diào)用。
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info("preHandle執(zhí)行。。。");
        return true;
    }

    /**
     * 請求處理完成后（渲染視圖后）的回調(diào)。將在處理程序執(zhí)行的任何結(jié)果上調(diào)用，從而允許進行適當?shù)馁Y源清理。
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        RequestHolder.remove();
        log.info("afterCompletion執(zhí)行。。。");
        return;
    }
}

Application類啟動類中配置自定義過濾器和攔截器

/**
 * 
 * @author zjq
 */
@SpringBootApplication
public class Application extends WebMvcConfigurationSupport {

    public static void main(String[] args) {
        SpringApplication.run(ConcurrencyApplication.class, args);
    }

    /**
     * 自定義過濾器
     * @return
     */
    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new HttpFilter());
        //設(shè)置自定義過濾器攔截的url
        filterRegistrationBean.addUrlPatterns("/threadLocal/*");
        return filterRegistrationBean;
    }

    /**
     * 定義自定義攔截器原先需要繼承WebMvcConfigurerAdapter
     * SpringBoot2.0后WebMvcConfigurerAdapter被定義成過時了，推薦使用繼承WebMvcConfigurationSupport
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new HttpInterceptor()).addPathPatterns("/**");
    }
}

定義調(diào)用接口

/**
 * ThreadLocal測試controller
 * @author zjq
 */
@Controller
@RequestMapping("/threadLocal")
public class ThreadLocalController {

    @RequestMapping("/test")
    @ResponseBody
    public Long test() {
        return RequestHolder.get();
    }
}