源代码

https://gitee.com/youlixishi/demo-world/tree/master/src/spring/springboot-Interceptor

新建springboot项目

详见pom文件

新建拦截器

public class TestInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("hi, this is from TestInterceptor");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

    }
}

注册拦截器

//spreingboot 会自动扫描到这个类，并且注册拦截器
@Configuration
public class AppConfigurer extends WebMvcConfigurerAdapter {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new TestInterceptor()).addPathPatterns("/**");
        super.addInterceptors(registry);
    }
}

preHandle（）方法添加断点

访问 http://localhost:8080/greeting， 发现命中断点，拦截器生效

ps:

1. preHandle方法中最后一个输入参数， 类型会变化， 可以猜猜看