Springboot自动装配原理_自动装配原理

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springboot自动装配原理详解

1)传统ssm整合redis的时候需要在xml的配置文件中进行大量的配置Bean

我们在这里使用springboot来代替ssm的整合，只是通过xml的形式来整合redis

第一步:加入配置

<dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-redis</artifactId> <version>2.0.9.RELEASE</version> </dependency> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.9.0</version> </dependency>

第二步: 配置xml的bean的配置

//配置连接池 <bean id=”poolConfig” class=”redis.clients.jedis.JedisPoolConfig”> <property name=”minIdle” value=”10″></property> <property name=”maxTotal” value=”20″></property> </bean> //配置连接工厂 <bean id=”jedisConnectionFactory” class=”org.springframework.data.redis.connection.jedis.JedisConnectionFactory”> <property name=”hostName” value=”47.104.128.12″></property> <property name=”password” value=”123456″></property> <property name=”database” value=”0″></property> <property name=”poolConfig” ref=”poolConfig”></property> </bean> //配置 redisTemplate 模版类 <bean id=”redisTemplate” class=”org.springframework.data.redis.core.RedisTemplate”> <property name=”connectionFactory” ref=”jedisConnectionFactory”/> <!–如果不配置Serializer，那么存储的时候默认使用String，如果用User类型存储，那么会提示错误User can’t cast to String！ –> <property name=”keySerializer”> <bean class=”org.springframework.data.redis.serializer.StringRedisSerializer”/> </property> <property name=”valueSerializer”> <bean class=”org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer”/> </property> <property name=”hashKeySerializer”> <bean class=”org.springframework.data.redis.serializer.StringRedisSerializer”/> </property> <property name=”hashValueSerializer”> <bean class=”org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer”/> </property> </bean>

第三步:导入配置

@ImportResource(locations = “classpath:beans.xml”) 此注解用于导入xml的配置文件

@SpringBootApplication @ImportResource(locations = “classpath:beans.xml”) @RestController public class TulingOpenAutoconfigPrincipleApplication { @Autowired private RedisTemplate redisTemplate; public static void main(String[] args) { SpringApplication.run(TulingOpenAutoconfigPrincipleApplication.class, args); } @RequestMapping(“/testRedis”) public String testRedis() { redisTemplate.opsForValue().set(“smlz”,”smlz”); return “OK”; } }

2)综上所述我们发现，若整合redis的时候通过传统的整合，进行了大量的配置,那么我们来看下通过springboot自动装配整合的对比

导入依赖:

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency>

修改yml配置文件

spring.redis.host=47.104.128.12 spring.redis.port=6379 spring.redis.password=123456

直接使用(下述代码可以不要配置，为了解决保存使用jdk的序列方式才配置的)

@Bean public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) { RedisTemplate<Object, Object> template = new RedisTemplate<>(); template.setDefaultSerializer(new Jackson2JsonRedisSerializer<Object>(Object.class)); template.setConnectionFactory(redisConnectionFactory); return template; }

3）传统整合和springboot自动装配优劣势分析

4）自动装配原理前的不得不说的几个注解

4.1)通过@Import注解来导入ImportSelector组件

①:写一个配置类在配置类上标注一个@Import的注解

@Configuration @Import(value = {TulingSelector.class}) public class TulingConfig { }

②：在@Import注解的value值写自己需要导入的组件

在selectImports方法中就是你需要导入组件的全类名

public class TulingSelector implements ImportSelector { @Override public String[] selectImports(AnnotationMetadata annotationMetadata) { return new String[]{“com.tuling.service.TulingServiceImpl“}; } }

核心代码:

@RestController public class TulingController { //自动注入 tulingServiceImpl @Autowired private TulingServiceImpl tulingServiceImpl; @RequestMapping(“testTuling”) public String testTuling() { tulingServiceImpl.testService(); return “tulingOk”; } } 这里是没有标注其他注解提供给spring包扫描的 public class TulingServiceImpl { public void testService() { System.out.println(“我是通过importSelector导入进来的service”); } }

1.2）通过@Import导入ImportBeanDefinitionRegistrar 从而进来导入组件

核心代码:

public class TulingImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar { @Override public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) { //定义一个BeanDefinition RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(TulingDao.class); //把自定义的bean定义导入到容器中 beanDefinitionRegistry.registerBeanDefinition(“tulingDao”,rootBeanDefinition); } } 通过ImportSelector功能导入进来的 public class TulingServiceImpl { @Autowired private TulingDao tulingDao; public void testService() { tulingDao.testTulingDao(); System.out.println(“我是通过importSelector导入进来的service”); } } 通过ImportBeanDefinitionRegistar导入进来的 public class TulingDao { public void testTulingDao() { System.out.println(“我是通过ImportBeanDefinitionRegistrar导入进来tulingDao组件”); } }

测试结果:

1.3)spring底层条件装配的原理@Conditional

应用要求:比如我有二个组件,一个是TulingLog 一个是TulingAspect

而TulingLog 是依赖TulingAspect的只有容器中有TulingAspect组件才会加载TulingLog

tulingLog组件依赖TulingAspect组件 public class TulingLog { } tulingAspect组件 public class TulingAspect { }

①:自定义条件组件条件

public class TulingConditional implements Condition { @Override public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) { //容器中包含tulingAspect组件才返回Ture if(conditionContext.getBeanFactory().containsBean(“tulingAspect”)){ return true; }else{ return false; } } } ————————————-该情况下会加载二个组件————————————————- @Bean public TulingAspect tulingAspect() { System.out.println(“TulingAspect组件自动装配到容器中”); return new TulingAspect(); } @Bean @Conditional(value = TulingConditional.class) public TulingLog tulingLog() { System.out.println(“TulingLog组件自动装配到容器中”); return new TulingLog(); } ————————————-二个组件都不会被加载—————————————- /*@Bean**/ public TulingAspect tulingAspect() { System.out.println(“TulingAspect组件自动装配到容器中”); return new TulingAspect(); } @Bean @Conditional(value = TulingConditional.class) public TulingLog tulingLog() { System.out.println(“TulingLog组件自动装配到容器中”); return new TulingLog(); }

自动装配原理分析从@SpringbootApplication入手分析

springboot自动装配流程图

让我们仔细分析

org.springframework.boot.autoconfigure.AutoConfigurationImportSelector#selectImports

public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered { @Override public String[] selectImports(AnnotationMetadata annotationMetadata) { if (!isEnabled(annotationMetadata)) { return NO_IMPORTS; } AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader .loadMetadata(this.beanClassLoader); AnnotationAttributes attributes = getAttributes(annotationMetadata); //去mata-info/spring.factories文件中查询 EnableAutoConfiguration对于值 List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes); //去除重复的配置类，若我们自己写的starter 可能存主重复的 configurations = removeDuplicates(configurations); Set<String> exclusions = getExclusions(annotationMetadata, attributes); checkExcludedClasses(configurations, exclusions); configurations.removeAll(exclusions); //根据maven 导入的启动器过滤出需要导入的配置类 configurations = filter(configurations, autoConfigurationMetadata); fireAutoConfigurationImportEvents(configurations, exclusions); return StringUtils.toStringArray(configurations); } } //去spring.factories 中去查询EnableAutoConfirution类 private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) { MultiValueMap<String, String> result = cache.get(classLoader); if (result != null) { return result; } try { Enumeration<URL> urls = (classLoader != null ? classLoader.getResources(FACTORIES_RESOURCE_LOCATION) : ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION)); result = new LinkedMultiValueMap<>(); while (urls.hasMoreElements()) { URL url = urls.nextElement(); UrlResource resource = new UrlResource(url); Properties properties = PropertiesLoaderUtils.loadProperties(resource); for (Map.Entry<?, ?> entry : properties.entrySet()) { List<String> factoryClassNames = Arrays.asList( StringUtils.commaDelimitedListToStringArray((String) entry.getValue())); result.addAll((String) entry.getKey(), factoryClassNames); } } cache.put(classLoader, result); return result; } catch (IOException ex) { throw new IllegalArgumentException(“Unable to load factories from location [” FACTORIES_RESOURCE_LOCATION “]”, ex); } }