目录

前言

一、结构中包含的角色

二、拦截器使用

1.拦截器角色

 a.自定义拦截器UserValidateInterceptor，UserUpdateInterceptor，UserEditNameInterceptor

 b.拦截器配置者UserInterceptorChainConfigure，任意组装拦截器顺序

c.拦截器管理者UserInterceptorChainManager

2.运行结果展示

a.使用代码

三、拦截器调用解说

1.项目启动，初始化bean

2.方法执行 

四、代码下载

总结

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前言

拦截过滤器模式,简称拦截器模式，是责任链模式的一种衍生模式。用于对业务程序做一些预处理/后处理

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一、结构中包含的角色

1. Interceptor（抽象处理者）
2. InterceptorChain（责任链）
3. InterceptorChainBuilder（责任链建造者）
4. AbstractInterceptorChainManager（链条管理者）
5. InterceptorChainConfigure（链条配置者)

二、拦截器使用

1.拦截器角色

 a.自定义拦截器UserValidateInterceptor，UserUpdateInterceptor，UserEditNameInterceptor

/*** 校验用户* @author liangxi.zeng*/
@Component
public class UserValidateInterceptor implements Interceptor<User> {/*** 拦截方法** @param user*/@Overridepublic void interceptor(User user) {if(user.getAge() != 10) {throw new CommonException("年龄不对");}System.out.println("校验用户"+user);}
}

 b.拦截器配置者UserInterceptorChainConfigure，任意组装拦截器顺序

@Component
public class UserInterceptorChainConfigureimplements InterceptorChainConfigure<User,InterceptorChainBuilder<User>> {/*** 拦截器链配置** @param interceptorChainBuilder 拦截器链构造器*/@Overridepublic void configure(InterceptorChainBuilder<User> interceptorChainBuilder) {interceptorChainBuilder.pre().addInterceptor(UserValidateInterceptor.class).post().addInterceptor(UserUpdateInterceptor.class).addInterceptor(UserEditNameInterceptor.class);}
}

c.拦截器管理者UserInterceptorChainManager

/*** @author liangxi.zeng* 拦截器链管理类*/
@Component
public class UserInterceptorChainManager 
extends AbstractInterceptorChainManager<User> {public UserInterceptorChainManager(List<Interceptor<User>> interceptorList,List<InterceptorChainConfigure<User, InterceptorChainBuilder<User>>> configureList) {super(interceptorList, configureList);}
}

2.运行结果展示

a.使用代码

/*** @author liangxi.zeng*/
@RestController
@RequestMapping("/demo")
public class DemoController {@Autowiredprivate UserInterceptorChainManager userInterceptorChainManager;@Autowiredprivate UserService userService;@RequestMapping("/user")public String user() {User user = new User();user.setId("111");user.setName("liangxi");user.setAge(10);userInterceptorChainManager.doInterceptor(user,(u) -> {// 内部创建用户userService.save(user);});return "success";}}

三、拦截器调用解说

1.项目启动，初始化bean

a.初始化责任链管理者UserInterceptorChainManager，调用父类AbstractInterceptorChainManager方法initInterceptorChain，通过责任链建造者初始化责任链

 public AbstractInterceptorChainManager(List<Interceptor<T>> interceptorList,List<InterceptorChainConfigure<T, InterceptorChainBuilder<T>>> configureList) {interceptorChain = initInterceptorChain(interceptorList, configureList);LOGGER.info("Register {} InterceptorChain, names are [{}]",interceptorList);}private InterceptorChain<T> initInterceptorChain(List<Interceptor<T>> interceptorList,List<InterceptorChainConfigure<T, InterceptorChainBuilder<T>>> configureList) {if (CollectionUtils.isEmpty(interceptorList)) {throw new IllegalArgumentException("Interceptors is empty.");}if (CollectionUtils.isEmpty(configureList)) {throw new IllegalArgumentException("Interceptor configurers is empty.");}InterceptorChainBuilder<T> builder = new InterceptorChainBuilder<>(interceptorList);configureList.sort(AnnotationAwareOrderComparator.INSTANCE);configureList.forEach(configurer -> {configurer.configure(builder);});return builder.performBuild();}

 b.责任链建造者，完成对业务方法前后逻辑的织入

public InterceptorChain performBuild() {List<Interceptor<T>> preInterceptors = filterInterceptor(preInterceptorList);List<Interceptor<T>> postInterceptors = filterInterceptor(postInterceptorList);if (preInterceptors.isEmpty() && postInterceptors.isEmpty()) {throw new IllegalStateException("Registered Pre-Interceptors and Post-Interceptors is empty.");}Consumer<T> preConsumer = (T t) -> {};Consumer<T> postConsumer = (T t) -> {};if (!preInterceptors.isEmpty()) {preConsumer = (T obj) -> {for (Interceptor<T> item : preInterceptors) {item.interceptor(obj);}};}if (!postInterceptors.isEmpty()) {postConsumer = (T obj) -> {for (Interceptor<T> item : postInterceptors) {item.interceptor(obj);}};}return new InterceptorChain(preConsumer,postConsumer);}

2.方法执行 

a.从userInterceptorChainManager.doInterceptor 到 interceptorChain.doExecute(target, operation);下面代码，完成代码逻辑

  /*** 拦截器调用入口，将核心操作封装成 Consumer 对象传入。** @param target    The target to handle.* @param operation The core operation to intercept.*/public final void doExecute(T target, Operation<T> operation) {preConsumer.accept(target);if (operation != null) {operation.execute(target);}postConsumer.accept(target);}

四、代码下载

设计模式可运行代码https://gitee.com/zenglx/design-pattern.git

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总结

前后端请求，可以用现成的filter和spring的Interceptor解决，业务自己的拦截器链模式，可以解决繁琐业务重复代码的问题