SpringBoot--拦截器(Interceptor)--使用/教程/实例

红太狼 2023-10-01 18:18 26阅读 0赞

原文网址：[SpringBoot--拦截器(Interceptor)--使用/教程/实例\_IT利刃出鞘的博客-CSDN博客][SpringBoot--_Interceptor_--_IT_-CSDN]

## 简介 ##

**说明**

本文用示例介绍SpringBoot（SpringMVC）中的拦截器的用法。

**使用场景**

*  日志记录：记录请求信息的日志，以便进行信息监控、信息统计、计算PV（Page View）等
 *  权限检查：如登录检测，进入处理器检测检测是否登录
 *  性能监控：通过拦截器在进入处理器之前记录开始时间，在处理完后记录结束时间，从而得到该请求的处理时间。（反向代理，如apache也可以自动记录）；
 *  通用行为：读取cookie得到用户信息并将用户对象放入请求，从而方便后续流程使用，还有如提取Locale、Theme信息等，只要是多个处理器都需要的即可使用拦截器实现。

**Interceptor 的相关方法**

Spring 中主要通过 HandlerInterceptor 接口来实现请求的拦截，实现 HandlerInterceptor 接口需要实现下面三个方法：

1.  **preHandle()** – 在handler执行之前，返回 boolean 值，true 表示继续执行，false 为停止执行并返回。
2.  **postHandle()**  – 在handler执行之后, 可以在返回之前对返回的结果进行修改
3.  **afterCompletion()** – 在请求完全结束后调用，可以用来统计请求耗时等等

**推荐写法**

*  实现WebMvcConfigurer接口是官方推荐的

**不推荐写法**

*  实现WebMvcConfigurerAdapter：Spring5.0之后是废弃的。
 *  继承WebMvcConfigurationSupport：会导致yml的配置失效。原因：WebMvcAutoConfiguration有个条件注解：@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)

## 实例1：单拦截器拦截所有 ##

### 代码 ###

**拦截器类**

package com.example.interceptor;
    
    import org.springframework.lang.Nullable;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class MyInterceptor implements HandlerInterceptor {
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                                 Object handler) throws Exception {
            System.out.println("MyInterceptor.preHandle");
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response,
                               Object handler, @Nullable ModelAndView modelAndView) throws Exception {
            System.out.println("MyInterceptor.postHandle");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                    Object handler, @Nullable Exception ex) throws Exception {
            System.out.println("MyInterceptor.afterCompletion");
        }
    }

**配置类**

package com.example.interceptor;
    
    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 InterceptorConfig implements WebMvcConfigurer {
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            registry.addInterceptor(new MyInterceptor());
    //        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/hello/test2");
        }
    }

**Controller**

package com.example.controller;
    
    import com.example.entity.User;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    @RequestMapping("/hello")
    public class HelloController {
        @RequestMapping("/test1")
        public User test1(User user) {
            System.out.println("HelloController.test1");
            return user;
        }
    }

**实体类**

package com.example.entity;
    
    import lombok.Data;
    
    @Data
    public class User {
        private Integer id;
        private String name;
        private Integer age;
    }

### **测试** ###

**postman访问**：[http://localhost:8080/hello/test1?name=Tony][http_localhost_8080_hello_test1_name_Tony]

后端结果：

MyInterceptor.preHandle
    HelloController.test1
    MyInterceptor.postHandle
    MyInterceptor.afterCompletion

postman结果

{
        "id": null,
        "name": "Tony",
        "age": null
    }

## 实例2：单拦截器拦截特定URL ##

### 代码 ###

**拦截器类**

**配置类**

package com.example.interceptor;
    
    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 InterceptorConfig implements WebMvcConfigurer {
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
    //        registry.addInterceptor(new MyInterceptor());
           registry.addInterceptor(new MyInterceptor()).addPathPatterns("/hello/test2");
        }
    }

**Controller**

**实体类**

package com.example.entity;
    
    import lombok.Data;
    
    @Data
    public class User {
        private Integer id;
        private String name;
        private Integer age;
    }

### **测试** ###

postman访问：[http://localhost:8080/hello/test1?name=Tony][http_localhost_8080_hello_test1_name_Tony]

后端结果：

HelloController.test1

postman结果

{
        "id": null,
        "name": "Tony",
        "age": null
    }

## 实例3：单拦截器结合注解 ##

使用场景示例：在需要登录验证的Controller的方法上使用注解。当然，也可以直接通过HttpServletRequest获得URI来判断。

### 代码 ###

**注解类**

package com.example.interceptor;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /**
     * 在需要登录验证的Controller的方法上使用此注解
     */
    @Target({ElementType.METHOD})      // 可用在方法名上
    @Retention(RetentionPolicy.RUNTIME)// 运行时有效
    public @interface LoginRequired {
    	
    }

**拦截器类**

package com.example.interceptor;
    
    import org.springframework.lang.Nullable;
    import org.springframework.web.method.HandlerMethod;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.lang.reflect.Method;
    
    public class MyInterceptor3 implements HandlerInterceptor {
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                                 Object handler) throws Exception {
            System.out.println("MyInterceptor3.preHandle");
            // 如果不是映射到方法直接通过
            if (!(handler instanceof HandlerMethod)) {
                return true;
            }
    
            // 方法注解级拦截器
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            Method method = handlerMethod.getMethod();
    
            // 判断接口是否需要登录。也可用method.isAnnotationPresent(LoginRequired.class)
            LoginRequired methodAnnotation = method.getAnnotation(LoginRequired.class);
            // 有 @LoginRequired 注解，需要认证
            if (methodAnnotation != null) {
                // 取缓存，SESSION，权限判断等
                System.out.println("   权限判断等");
                return true;
            }
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response,
                               Object handler, @Nullable ModelAndView modelAndView) throws Exception {
            System.out.println("MyInterceptor3.postHandle");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                    Object handler, @Nullable Exception ex) throws Exception {
            System.out.println("MyInterceptor3.afterCompletion");
        }
    }

**拦截器配置**

package com.example.interceptor;
    
    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 InterceptorConfig implements WebMvcConfigurer {
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            //这个顺序会决定拦截器执行顺序
            registry.addInterceptor(new MyInterceptor3());
            // registry.addInterceptor(new MyInterceptor2());
            // registry.addInterceptor(new MyInterceptor1());
            // registry.addInterceptor(new MyInterceptor()).addPathPatterns("/hello/test2");
        }
    }

**controller**

package com.example.controller;
    
    import com.example.entity.User;
    import com.example.interceptor.LoginRequired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    @RequestMapping("/hello")
    public class HelloController {
    
        @LoginRequired
        @RequestMapping("/test1")
        public User test1(User user) {
            System.out.println("HelloController.test1");
            return user;
        }
    }

**实体类**

package com.example.entity;
    
    import lombok.Data;
    
    @Data
    public class User {
        private Integer id;
        private String name;
        private Integer age;
    }

### **测试** ###

**postman访问**：[http://localhost:8080/hello/test1?name=Tony][http_localhost_8080_hello_test1_name_Tony]

后端结果

MyInterceptor3.preHandle
       权限判断等
    HelloController.test1
    MyInterceptor3.postHandle
    MyInterceptor3.afterCompletion

postman结果

{
        "id": null,
        "name": "Tony",
        "age": null
    }

## 实例4：多个拦截器拦截所有 ##

### 代码 ###

**拦截器1**

package com.example.interceptor;
    
    import org.springframework.lang.Nullable;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class MyInterceptor1 implements HandlerInterceptor {
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                                 Object handler) throws Exception {
            System.out.println("MyInterceptor1.preHandle");
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response,
                               Object handler, @Nullable ModelAndView modelAndView) throws Exception {
            System.out.println("MyInterceptor1.postHandle");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                    Object handler, @Nullable Exception ex) throws Exception {
            System.out.println("MyInterceptor1.afterCompletion");
        }
    }

**拦截器2**

package com.example.interceptor;
    
    import org.springframework.lang.Nullable;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class MyInterceptor2 implements HandlerInterceptor {
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                                 Object handler) throws Exception {
            System.out.println("MyInterceptor2.preHandle");
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response,
                               Object handler, @Nullable ModelAndView modelAndView) throws Exception {
            System.out.println("MyInterceptor2.postHandle");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                    Object handler, @Nullable Exception ex) throws Exception {
            System.out.println("MyInterceptor2.afterCompletion");
        }
    }

**配置类**

package com.example.interceptor;
    
    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 InterceptorConfig implements WebMvcConfigurer {
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            //如果不写.order，则按照先后顺序
            registry.addInterceptor(new MyInterceptor1()).order(0);
            registry.addInterceptor(new MyInterceptor2()).order(1);
        }
    }

**controller**

**实体类**

package com.example.entity;
    
    import lombok.Data;
    
    @Data
    public class User {
        private Integer id;
        private String name;
        private Integer age;
    }

### **测试** ###

#### **测试1：测试接口** ####

postman访问：[http://localhost:8080/hello/test1?name=Tony][http_localhost_8080_hello_test1_name_Tony]

后端结果

MyInterceptor1.preHandle
    MyInterceptor2.preHandle
    HelloController.test1
    MyInterceptor2.postHandle
    MyInterceptor1.postHandle
    MyInterceptor2.afterCompletion
    MyInterceptor1.afterCompletion

postman结果

{
        "id": null,
        "name": "Tony",
        "age": null
    }

#### 测试2：颠倒顺序 ####

**配置类（颠倒顺序）**

package com.example.interceptor;
    
    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 InterceptorConfig implements WebMvcConfigurer {
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            //如果不写.order，则按照先后顺序
            registry.addInterceptor(new MyInterceptor2()).order(0);
            registry.addInterceptor(new MyInterceptor1()).order(1);
        }
    }

**测试结果（颠倒顺序后）**

postman访问：[http://localhost:8080/hello/test1?name=Tony][http_localhost_8080_hello_test1_name_Tony]

后端结果

MyInterceptor2.preHandle
    MyInterceptor1.preHandle
    HelloController.test1
    MyInterceptor1.postHandle
    MyInterceptor2.postHandle
    MyInterceptor1.afterCompletion
    MyInterceptor2.afterCompletion

postman结果

{
        "id": null,
        "name": "Tony",
        "age": null
    }

## **其他网址** ##

[Spring Boot 优雅的配置拦截器方式 - GIT猿【边鹏】博客 - OSCHINA][Spring Boot _ - GIT_ - OSCHINA]  
[Spring Boot拦截器(Interceptor)详解 - 掘金][Spring Boot_Interceptor_ -]

[SpringBoot--_Interceptor_--_IT_-CSDN]: https://knife.blog.csdn.net/article/details/122912005
[http_localhost_8080_hello_test1_name_Tony]: http://localhost:8080/hello/test1?name=Tony
[Spring Boot _ - GIT_ - OSCHINA]: https://my.oschina.net/bianxin/blog/2876640
[Spring Boot_Interceptor_ -]: https://juejin.im/post/6844904020675559432