Spring 模式注解装配
- A stereotype annotation is an annotation that is used to declare the role that a component plays within the application. For example, the
@Repositoryannotation in the Spring Framework is a marker for any class that fulfills the role or stereotype of a repository (also known as Data Access Object or DAO).@Componentis a generic stereotype for any Spring-managed component. Any component annotated with@Componentis a candidate for component scanning. Similarly, any component annotated with an annotation that is itself meta-annotated with@Componentis also a candidate for component scanning. For example,@Serviceis meta-annotated with@Component.
- 模式注解是一种用于声明在应用中扮演“组件”角色的注解。如Spring Framework中的
@Repository标注在任何类上，用于扮演仓储角色的模式注解。@Component作为一种由Spring容器托管的通用模式组件，任何被@Component标准的组件均为组件扫描的候选对象。类似地，凡是被@Component元标注（meta-annotated）的注解，如@Service，当任何组件标注它时，也被视作组件扫描的候选对象。
Spring 模式注解装配 -> 举例
| Spring Framework 注解 | 场景说明 | 起始版本 |
|---|---|---|
@Component |
通用组件模式注解 | 2.5 |
@Repository |
数据仓储模式注解 | 2.0 |
@Service |
服务模式注解 | 2.5 |
@Controller |
Web控制器模式注解 | 2.5 |
@Configuration |
配置类模式注解 | 3.0 |
Spring 模式注解装配 -> 装配方式: @ComponentScan & <context:component-scan>
Spring Framework 5.1.0 Classpath Scanning and Managed Components
- 要自动检测这些类并注册相应的bean，您需要将
@ComponentScan添加到@Configuration类
@Configuration
@ComponentScan(basePackages = "org.example")
public class AppConfig {
...
}
等价xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 激活注解驱动特性 -->
<context:annotation-config>
<!-- 找寻被 @Component 或者其派生 Annotation 标记的类（Class），将它们注册为 Spring Bean -->
<context:component-scan base-package="org.example"/>
</beans>
- 以下示例显示忽略所有@Repository注释并使用“存根”存储库的配置
@Configuration
@ComponentScan(basePackages = "org.example",
includeFilters = @Filter(type = FilterType.REGEX, pattern = ".*Stub.*Repository"),
excludeFilters = @Filter(Repository.class))
public class AppConfig {
...
}
等价xml
<beans>
<context:component-scan base-package="org.example">
<context:include-filter type="regex"
expression=".*Stub.*Repository"/>
<context:exclude-filter type="annotation"
expression="org.springframework.stereotype.Repository"/>
</context:component-scan>
</beans>
Spring 模式注解装配 -> 自定义
定义注解
@FirstLevelRepository，从@Repository派生，其中，@Repository从@Component派生。
@FirstLevelRepository>@Repository>@Component
import org.springframework.stereotype.Repository;
import java.lang.annotation.*;
/**
* 一级 {@link Repository @Repository}
*
* @author zoz
* @since 1.0
*/
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Repository
public @interface FirstLevelRepository {
String value() default "";
}
定义注解
@SecondLevelRepository，从@FirstLevelRepository派生。
@SecondLevelRepository>@FirstLevelRepository>@Repository>@Component
import org.springframework.stereotype.Repository;
import java.lang.annotation.*;
/**
* 二级 {@link Repository}
*
* @author zoz
* @since 1.0
*/
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@FirstLevelRepository
public @interface SecondLevelRepository {
String value() default "";
}
定义类引用注解
@FirstLevelRepository
package com.imooc.diveinspringboot.configuration.repository;
import com.imooc.diveinspringboot.configuration.annotation.FirstLevelRepository;
@FirstLevelRepository(value = "myFirstLevelRepository")
public class MyFirstLevelRepository {
}
定义类引用注解
@SecondLevelRepository
package com.imooc.diveinspringboot.configuration.repository;
import com.imooc.diveinspringboot.configuration.annotation.SecondLevelRepository;
@SecondLevelRepository(value = "mySecondLevelRepository")
public class MySecondLevelRepository {
}
启动类，通过
@ComponentScan扫描所有引用了注解@Component或其派生的类，并获取类的实体。
import com.imooc.diveinspringboot.configuration.repository.MyFirstLevelRepository;
import com.imooc.diveinspringboot.configuration.repository.MySecondLevelRepository;
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;
@ComponentScan(basePackages = "com.imooc.diveinspringboot.configuration.repository")
public class RepositoryBootstrap {
public static void main(String[] args) {
ConfigurableApplicationContext context = new SpringApplicationBuilder(RepositoryBootstrap.class)
.web(WebApplicationType.NONE)
.run(args);
MyFirstLevelRepository myFirstLevelRepository = context.getBean("myFirstLevelRepository", MyFirstLevelRepository.class);
MySecondLevelRepository mySecondLevelRepository = context.getBean("mySecondLevelRepository", MySecondLevelRepository.class);
System.out.println("myFirstLevelRepository Bean: " + myFirstLevelRepository);
System.out.println("mySecondLevelRepository Bean: " + mySecondLevelRepository);
// 关闭上下文
context.close();
}
}
Spring 模式 @Enable 模块装配
Spring Framework 3.1 开始支持
@Enable模块装配，即将具有相同领域的功能组件集合，组合成一个独立的单元。
Spring 模式 @Enable 模块装配 -> 举例
| 框架实现 |
@Enable 注解模块 |
激活模块 |
|---|---|---|
| Spring Framework | @EnableWebMvc |
Web MVC 模块 |
@EnableTransactionManagement |
事务管理模块 | |
@EnableCaching |
Caching 模块 | |
@EnableMBeanExport |
JMX 模块 | |
@EnableAsync |
异步处理模块 | |
@EnableWebFlux |
Web Flux 模块 | |
@EnableAspectJAutoProxy |
AspectJ 代理模块 | |
| Spring Boot | @EnableAutoConfiguration |
自动装配模块 |
@EnableManagementContext |
Actuator 模块 | |
@EnableConfigurationProperties |
配置属性绑定模块 | |
@EnableOAuth2Sso |
OAuth2 单点登录模块 | |
| Spring Cloud | ||
@EnableEurekaServer |
Eureka 服务器模块 | |
@EnableConfigServer |
配置服务器模块 | |
@EnableFeignClients |
Feign 客户端模块 | |
@EnableZuulProxy |
服务网关 Zuul 模块 | |
@EnableCircuitBreaker |
服务熔断模块 |
Spring 模式 @Enable 模块装配 -> 实现方式: 注解驱动
- Spring Framework
@EnableWebMvc导入DelegatingWebMvcConfiguration
package org.springframework.web.servlet.config.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.Import;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
}
DelegatingWebMvcConfiguration添加@Configuration注解
@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
@Autowired(required = false)
public void setConfigurers(List<WebMvcConfigurer> configurers) {
if (!CollectionUtils.isEmpty(configurers)) {
this.configurers.addWebMvcConfigurers(configurers);
}
}
@Override
protected void configurePathMatch(PathMatchConfigurer configurer) {
this.configurers.configurePathMatch(configurer);
}
...
}
- 自定义
@EnableHelloConfiguration导入HelloConfiguration
import com.imooc.diveinspringboot.configuration.configuration.HelloConfiguration;
import org.springframework.context.annotation.Import;
import java.lang.annotation.*;
/**
* 激活 Hello 模块
*
* @author zozo
* @since 1.0
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(HelloConfiguration.class)
public @interface EnableHelloConfiguration {
}
HelloConfiguration添加@Configuration注解
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* Hello 配置
*
* @author zozo
* @since 1.0
*/
@Configuration
public class HelloConfiguration {
@Bean
public String hello() { // 方法名即 Bean 名称
return "Hello Bean";
}
}
引用 & 运行结果
import com.imooc.diveinspringboot.configuration.annotation.EnableHelloConfiguration;
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
@EnableHelloConfiguration
public class EnableHelloConfigurationBootstrap {
public static void main(String[] args) {
ConfigurableApplicationContext context = new SpringApplicationBuilder(EnableHelloConfigurationBootstrap.class)
.web(WebApplicationType.NONE)
.run(args);
// 查找 Bean
String hello = context.getBean("hello", String.class);
System.out.println("hello Bean: " + hello);
// 关闭上下文
context.close();
}
}
hello Bean: Hello Bean
Spring 模式 @Enable 模块装配 -> 实现方式: 接口编程
- Spring Framework
@EnableCaching导入CachingConfigurationSelector
package org.springframework.cache.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.AdviceMode;
import org.springframework.context.annotation.Import;
import org.springframework.core.Ordered;
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(CachingConfigurationSelector.class)
public @interface EnableCaching {
boolean proxyTargetClass() default false;
AdviceMode mode() default AdviceMode.PROXY;
int order() default Ordered.LOWEST_PRECEDENCE;
}
CachingConfigurationSelector继承AdviceModeImportSelector实现ImportSelector接口
public class CachingConfigurationSelector extends AdviceModeImportSelector<EnableCaching> {
private static final String PROXY_JCACHE_CONFIGURATION_CLASS =
"org.springframework.cache.jcache.config.ProxyJCacheConfiguration";
private static final String CACHE_ASPECT_CONFIGURATION_CLASS_NAME =
"org.springframework.cache.aspectj.AspectJCachingConfiguration";
...
@Override
public String[] selectImports(AdviceMode adviceMode) {
switch (adviceMode) {
case PROXY:
return getProxyImports();
case ASPECTJ:
return getAspectJImports();
default:
return null;
}
}
private String[] getProxyImports() {
List<String> result = new ArrayList<>(3);
result.add(AutoProxyRegistrar.class.getName());
result.add(ProxyCachingConfiguration.class.getName());
if (jsr107Present && jcacheImplPresent) {
result.add(PROXY_JCACHE_CONFIGURATION_CLASS);
}
return StringUtils.toStringArray(result);
}
...
}
- 自定义
@EnableHelloImportSelector导入HelloImportSelector
import com.imooc.diveinspringboot.configuration.configuration.HelloImportSelector;
import org.springframework.context.annotation.Import;
import java.lang.annotation.*;
/**
* 激活 Hello 模块
*
* @author zozo
* @since 1.0
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(HelloImportSelector.class)
public @interface EnableHelloImportSelector {
}
HelloImportSelector实现ImportSelector接口
import org.springframework.context.annotation.ImportSelector;
import org.springframework.core.type.AnnotationMetadata;
/**
* Hello {@link ImportSelector} 实现
*
* @author zozo
* @since 1.0
*/
public class HelloImportSelector implements ImportSelector {
@Override
public String[] selectImports(AnnotationMetadata importingClassMetadata) {
return new String[]{HelloConfiguration.class.getName()};
}
}
引用 & 运行结果
import com.imooc.diveinspringboot.configuration.annotation.EnableHelloImportSelector;
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
@EnableHelloImportSelector
public class EnableHelloImportSelectorBootstrap {
public static void main(String[] args) {
ConfigurableApplicationContext context = new SpringApplicationBuilder(EnableHelloImportSelectorBootstrap.class)
.web(WebApplicationType.NONE)
.run(args);
// 查找 Bean
String hello = context.getBean("hello", String.class);
System.out.println("hello Bean: " + hello);
// 关闭上下文
context.close();
}
}
hello Bean: Hello Bean
