1、pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.atguigu</groupId>
    <artifactId>pro28-springboot-interceptor</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!--所有springboot项目都必须继承自 spring-boot-starter-parent -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.0.5</version>
        <relativePath />  <!-- 根据情况添加 -->
    </parent>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!--web开发的场景启动器 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--导入配置处理器，配置文件自定义的properties配置都会有提示-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>
</project>

2、实现HandlerInterceptor接口

package com.atguigu.interceptor;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
@Component
public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        return true;
    }

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

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion...");
    }
}

3、实现WebMvcConfigurer接口

package com.atguigu.config;
import com.atguigu.interceptor.MyInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

    @Autowired
    private MyInterceptor myInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor).addPathPatterns("/**").excludePathPatterns("/hello/a/b");
    }
}

4、HelloController.java

package com.atguigu.controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/hello")
public class HelloController {

    @GetMapping("/a/b")
    public String h01() {
        return "Hello world!";
    }

    @GetMapping("/b")
    public String h02() {
        return "hi world!";
    }

    @GetMapping("/c")
    public String h03() {
        return "bye bye!";
    }
}

5、MyApplication.java

package com.atguigu;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class);
    }
}

 6、HandlerInterceptor

HandlerInterceptor是Spring MVC框架中的一种拦截器，类似于Servlet开发中的过滤器Filter。它用于在请求处理器执行前后进行预处理和后处理，可以用于实现权限检查、性能监控等操作。

在Spring MVC中，拦截器是一个接口，需要实现preHandle、postHandle和afterCompletion方法。其中，preHandle方法在请求处理器处理请求之前执行，可以进行编码、安全控制、权限校验等处理；postHandle方法在请求处理器处理请求之后、渲染视图之前执行，可以通过modelAndView对模型数据进行处理或对视图进行处理；afterCompletion方法在请求处理完成后执行，可以进行资源清理等工作。

在实现拦截器时，需要将拦截器注册到Spring MVC的配置文件中，并指定需要拦截的URL和处理器。当请求匹配到指定的URL时，拦截器就会自动执行。

总之，HandlerInterceptor是Spring MVC中非常有用的工具，可以用于实现各种处理操作，提高Web应用程序的性能和安全性。