概念
过滤器即 Servlet 过滤器，参见 Servlet 过滤器入门示例。
拦截器（Interceptor）通常是由特定的框架提供的，不是 Java EE 标准的一部分。
Spring 提供了多种类型的拦截器，如方法拦截器（MethodInterceptor）和控制器拦截器（HandlerInterceptor）。
方法拦截器可以用于 AOP（面向切面编程），而控制器拦截器用于处理请求和响应。
拦截器示例
下面的示例演示如何使用 Spring MVC 的HandlerInterceptor。
项目结构
SpringInterceptorExample/
├── src/
│ ├── main/
│ │ ├── java/
│ │ │ └── com/
│ │ │ └── example/
│ │ │ ├── MyInterceptor.java
│ │ │ ├── HelloController.java
│ │ │ ├── WebConfig.java
│ │ │ └── Application.java
│ │ └── resources/
│ │ └── application.properties
└── pom.xml
1. Maven 依赖（pom.xml）
<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.example</groupId><artifactId>SpringInterceptorExample</artifactId><version>1.0-SNAPSHOT</version><properties><java.version>1.8</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring-boot.version>2.6.13</spring-boot.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><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>1.8</source><target>1.8</target><encoding>UTF-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring-boot.version}</version><configuration><mainClass>com.example.Application</mainClass><skip>true</skip></configuration><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></build>
</project>
2. 拦截器实现（MyInterceptor.java）
package com.example;import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;@Component
public class MyInterceptor implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("Before handling the request: " + request.getRequestURI());return true; // 返回 true 继续处理请求}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("After handling the request: " + request.getRequestURI());}
}
3. 控制器实现（HelloController.java）
package com.example;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 {@GetMappingpublic String sayHello() {return "Hello, World!"; // 返回字符串响应}
}
4. Web 配置（WebConfig.java）
package com.example;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 WebConfig implements WebMvcConfigurer {@Autowiredprivate MyInterceptor myInterceptor;@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(myInterceptor).addPathPatterns("/hello/**"); // 拦截 /hello 路径}
}
5. 启动类（Application.java）
package com.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}
}
6. 运行项目
-
使用 Maven 构建项目：
mvn clean package -
运行 Spring Boot 应用：
mvn spring-boot:run -
在浏览器中访问
http://localhost:8080/hello，你应该能看到 "Hello, World!" 的响应，同时在控制台中会输出拦截器的日志。
