自己学习的时候可以自定义注解可以学习用，标志方便清晰；
RetentionPolicy.SOURCE -- 加载不运行注解1，不推荐写法
/**
* 课程里用来标记【不推荐】的类或者写法
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface NotRecommend {
String value() default "";
}注解2 备注推荐的注解写法
/**
* 课程里用来标记【推荐】的类或者写法
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface Recommend {
String value() default "";
}注解3 线程安全的注解写法
/**
* 课程里用来标记【线程安全】的类或者写法
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface ThreadSafe {
String value() default "";
}注解4 线程不安全的注解写法
/**
* 课程里用来标记【线程不安全】的类或者写法
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface NotThreadSafe {
String value() default "";
}使用SpringBoot的Application来进行运行
@SpringBootApplication
public class ConcurrencyApplication extends WebMvcConfigurerAdapter{
public static void main(String[] args) {
SpringApplication.run(ConcurrencyApplication.class, args);
}
@Bean
public FilterRegistrationBean httpFilter() {
FilterRegistrationBean registrationBean = new FilterRegistrationBean();
registrationBean.setFilter(new HttpFilter());
registrationBean.addUrlPatterns("/threadLocal/*");
return registrationBean;
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new HttpInterceptor()).addPathPatterns("/**");
}
}线程不安全的一个测试类
@Slf4j
@NotThreadSafe
public class ConcurrencyTest {
// 请求总数
public static int clientTotal = 5000;
// 同时并发执行的线程数
public static int threadTotal = 200;
public static int count = 0;
public static void main(String[] args) throws Exception {
ExecutorService executorService = Executors.newCachedThreadPool();
final Semaphore semaphore = new Semaphore(threadTotal);
final CountDownLatch countDownLatch = new CountDownLatch(clientTotal);
for (int i = 0; i < clientTotal ; i++) {
executorService.execute(() -> {
try {
semaphore.acquire();
add();
semaphore.release();
} catch (Exception e) {
log.error("exception", e);
}
countDownLatch.countDown();
});
}
countDownLatch.await();
executorService.shutdown();
log.info("count:{}", count);
}
private static void add() {
count++;
}
}可以使用SpringBoot的嵌入式的Servlet的Filter模式进行过滤器进行 自定义定义
@Slf4j
public class HttpFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
log.info("do filter, {}, {}", Thread.currentThread().getId(), request.getServletPath());
RequestHolder.add(Thread.currentThread().getId());
filterChain.doFilter(servletRequest, servletResponse);
}
@Override
public void destroy() {
}
}SpringBoot的自定义拦截器
@Slf4j
public class HttpInterceptor extends HandlerInterceptorAdapter {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
log.info("preHandle");
return true;
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
RequestHolder.remove();
log.info("afterCompletion");
return;
}
}进行运行主类-SpringBoot的主类
public class ServletInitializer extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(ConcurrencyApplication.class);
}
}添加一个访问控制器
测试一下：
@Controller
@Slf4j
public class TestController {
@RequestMapping("/test")
@ResponseBody
public String test() {
return "test";
}
}
