攔截器對使用SpringMvc的開發人員來說特別熟悉，因為你只要想去做好一個專案必然會用到它，攔截器在我們平時的專案中用處有很多，如：日志記錄、用戶登錄狀態攔截、安全攔截等等，而SpringBoot內部集成的是SpringMVC控制框架，所以使用起來跟SpringMVC沒有區別，只是在配置上有點不同，本文只介紹如何在springboot中使用攔截器的基本方式，

環境/版本一覽：

• 開發工具：Intellij IDEA 2020.2.3
• springboot：2.3.7.RELEASE
• jdk：1.8.0_211
• maven: 3.6.3

專案結構

搭建專案

• pom.xml配置

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.niu</groupId>
    <artifactId>springboot-interceptor</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <name>springboot-interceptor</name>
    <description>springboot攔截器使用</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

• 寫一個控制器，加入一個介面

package com.niu.springbootinterceptor.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @description: 控制器
 * @author: nxq email: niuxiangqian163@163.com
 * @createDate: 2020/12/22 3:28 下午
 * @updateUser: nxq email: niuxiangqian163@163.com
 * @updateDate: 2020/12/22 3:28 下午
 * @updateRemark:
 * @version: 1.0
 **/
@RestController
public class MyController {


    @GetMapping("test")
    public Object test(){
        System.out.println("test介面");
        return "ok";
    }
}

• 撰寫攔截器

package com.niu.springbootinterceptor.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @description: 攔截器
 * @author: nxq email: niuxiangqian163@163.com
 * @createDate: 2020/12/22 3:26 下午
 * @updateUser: nxq email: niuxiangqian163@163.com
 * @updateDate: 2020/12/22 3:26 下午
 * @updateRemark:
 * @version: 1.0
 **/
public class MyInterceptor  implements HandlerInterceptor {

    /**
     * 訪問介面之前攔截
     * 可以做登陸判斷、訪問權限判斷、記錄日志，，，
     * 方法return true是允許訪問介面  return false是拒絕訪問
     * @return boolean
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("準備訪問介面");
        return true; //放行所有介面

    }

    //在controller方法執行完畢執行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("controller執行完畢");


    }
    //可以在這里捕捉例外
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("頁面渲染完成，準備回傳給客戶端");

    }
}

• 撰寫配置類，加入攔截器

package com.niu.springbootinterceptor.config;

import com.niu.springbootinterceptor.interceptor.MyInterceptor;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;


/**
 * @description:
 * @author: nxq email: niuxiangqian163@163.com
 * @createDate: 2020/12/22 3:26 下午
 * @updateUser: nxq email: niuxiangqian163@163.com
 * @updateDate: 2020/12/22 3:26 下午
 * @updateRemark:
 * @version: 1.0
 **/
@Component
public class WebConfig  implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //添加攔截器并設定攔截的訪問路徑 *代表全匹配
       // registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**");
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/test");
    }
}

• 主類

package com.niu.springbootinterceptor;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringbootInterceptorApplication {

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

}

啟動測驗

• 訪問介面

• 控制臺列印

攔截器的基本使用說完了，但它在實際的場景應用作用十分強大，慢慢在實踐中探索吧

代碼已經推送至github：https://github.com/1603565290m/springboot-interceptor