SpringBoot------自定义拦截器

1.添加pom.xml使用的依赖

<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>top.ytheng</groupId>
  <artifactId>springboot-demo</artifactId>
  <version>0.0.1</version>
  <packaging>jar</packaging>
  
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <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>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
              <scope>true</scope>
        </dependency>
    </dependencies>

    <build>
        <!-- 打包的名称 -->
        <finalName>myspringboot</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2.添加拦截器Login业务类

package top.ytheng.demo.intecpter;

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

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

/**
 * 拦截器业务类
 * 
 * */
public class LoginIntecepter implements HandlerInterceptor {

    /**
     * 调用Controller之前
     * 
     * */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("LoginIntecepter------>preHandle");
        
        //这里可以做一些access_token的校验
        String token = request.getParameter("token");
        System.out.println(token);
        
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }

    /**
     * 调用完Controller之后，视图渲染之前
     * 
     * */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("LoginIntecepter------>postHandle");
        
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    /**
     * 整个完成之后
     * 
     * */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("LoginIntecepter------>afterCompletion");
        
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

3.添加拦截器2业务类

package top.ytheng.demo.intecpter;

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

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

/**
 * 拦截器业务类
 * 
 * */
public class TwoIntecepter implements HandlerInterceptor {

    /**
     * 调用Controller之前
     * 
     * */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("TwoIntecepter------>preHandle");
        
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }

    /**
     * 调用完Controller之后，视图渲染之前
     * 
     * */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("TwoIntecepter------>postHandle");
        
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    /**
     * 整个完成之后
     * 
     * */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("TwoIntecepter------>afterCompletion");
        
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }

    
}

4.添加自定义拦截器

package top.ytheng.demo.intecpter;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/*
 * 自定义拦截器
 * 
 * */
@Configuration
public class CustomWebMvcConfigurer implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // TODO Auto-generated method stub
        //拦截全部/**
        //最后一个必须为/**,如果是目录的话则是/*/
        //第一个拦截器
        registry.addInterceptor(new LoginIntecepter()).addPathPatterns("/api2/*/**");
        //排除拦截的地址
        //    .excludePathPatterns("/api2/xxx");
        
        //第二个拦截器
        registry.addInterceptor(new TwoIntecepter()).addPathPatterns("/api2/*/**");
        
        WebMvcConfigurer.super.addInterceptors(registry);
    }
}

5.添加控制器

package top.ytheng.demo.controller;

import java.util.HashMap;
import java.util.Map;

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

@RestController
@RequestMapping("/api2/v1")
public class CustomIntecepterController {

    @GetMapping("/test/filter")
    public Object testFilter() {
        System.out.println("CustomIntecepterController------>testFilter");
        Map<String, Object> map = new HashMap<>();
        map.put("username", "theng");
        map.put("password", "123");
        return map;
    }
}

6.添加启动类

package top.ytheng.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication //等于下面3个
//@SpringBootConfiguration
//@EnableAutoConfiguration
//@ComponentScan
//Filter,拦截器用到
@ServletComponentScan
public class DemoApplication {

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

7.右键项目Run As启动，测试地址

http://localhost:8080/api2/v1/test/filter

测试结果截图:

总结:

1.自定义拦截器 HandlerInterceptor
preHandle:调用Controller某个方法之前
postHandle:Controller之后调用，视图渲染之前，如果控制器Controller出现了异常，则不会执行此方法
afterCompletion:不管有没有异常，这个afterCompletion都会被调用，用于资源清理

2.按照注册顺序进行拦截，先注册，先被拦截

拦截器不生效常见问题：
1)是否有加@Configuration
2)拦截路径是否有问题** 和 *
3)拦截器最后路径一定要"/**"，如果是目录的话则是/*/

Filter
    是基于函数回调doFilter()，而Interceptor则是基于AOP思想；
    只在Servlet前后起作用，而Interceptor能够深入到方法前后，异常抛出前后等；
    依赖于Servlet容器即Web应用中，而Interceptor不依赖于Servlet容器，所以可以运行在多种环境中；
    在接口调用的生命周期里，Interceptor可以被多次调用，而Filter只能在容器初始化时调用一次；
    
3.Filter和Interceptor的执行顺序
过滤前->拦截前->action执行->拦截后->过滤后

另附：