四、SpringBoot整合拦截器

本节我将带大家来学习一下springboot2.0中是如何整合拦截器。

我们需要引入的依赖依旧是springboot2.0父工程和web组件

	<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

编写我们的启动类Main

/**
 * @author 小吉
 * @description springboot启动类
 * @date 2020/5/23
 */
@SpringBootApplication
public class Main {
    public static void main(String[] args) {
        SpringApplication.run(Main.class,args);
    }
}

1、创建拦截器

我们通过实现HandlerInterceptor接口来做我们的拦截器，可以查看到HandlerInterceptor接口源码，该接口定义的三个方法都使用default关键字修饰，这个是JDK8新增加的特性。被default关键字修饰的方法可以不实现，可以默认使用。那么我们来重新实现一下这三个方法。

HandlerInterceptor接口源码展示（已经去除注释）：

public interface HandlerInterceptor {
	default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {

		return true;
	}
	default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			@Nullable ModelAndView modelAndView) throws Exception {
	}
	default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
			@Nullable Exception ex) throws Exception {
	}

}

MyIntercept类源码

/**
 * @author 小吉
 * @description springboot2.0整合拦截器
 * @date 2020/5/23
 */
@Component
public class MyIntercept implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("请求执行之前拦截..." + System.currentTimeMillis());
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("请求执行中..." + System.currentTimeMillis());
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("请求执行完成..." + System.currentTimeMillis());
    }
}

2、注册拦截器

/**
 * @author 小吉
 * @description web配置
 * @date 2020/5/23
 */
@Configuration
public class WebConfig {
    @Autowired
    private MyIntercept myIntercept;
    
    @Bean
    public WebMvcConfigurer WebMvcConfigurer() {
        return new WebMvcConfigurer() {
            public void addInterceptors(InterceptorRegistry registry) {
                registry.addInterceptor(myIntercept).addPathPatterns("/*");
            };
        };
    }
}

将MyIntercept拦截器注册到springboot的web配置中。

3、编写控制器测试

/**
 * @author 小吉
 * @description 测试拦截器拦截
 * @date 2020/5/23
 */
@RestController
public class HelloController {

    @RequestMapping("hello")
    public String hello(){
        System.out.println("进入hello方法..." + System.currentTimeMillis());
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "进入hello方法";
    }

}

请求执行之前拦截...1590244547663
进入hello方法...1590244547671
请求执行中...1590244549691
请求执行完成...1590244549691