springboot自动装配原理详解-CFANZ编程社区

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，那么存储的时候缺省使用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") 可以导入xml的配置文件 

@SpringBootApplication 
@ImportResource(locations = "classpath:beans.xml")
@RestController
public class TestOpenAutoconfigPrincipleApplication {

@Autowired 
private RedisTemplate redisTemplate;

public static void main(String[] args) { 

    SpringApplication.run(TestOpenAutoconfigPrincipleApplication.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=127.0.0.1
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

4）自动装配原理前的不得不说的几个注解

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 = {TestSelector.class})
public class TestConfig { }

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 TestSelector implements ImportSelector { 

    @Override 
    public String[] selectImports(AnnotationMetadata annotationMetadata) { 
        return new String[]{"com.link.service.TestServiceImpl"}; 
    } 

}

核心代码:

@RestController public class TestController {

//自动注入 testServiceImpl 
@Autowired 
private TestServiceImpl testServiceImpl;

@RequestMapping("test") 
public String test() {

testServiceImpl.testService();

return "ok"; }

}

这里是没有标注其他注解提供给spring包扫描的

public class TestServiceImpl {

    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 TestImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {

@Override 
public void registerBeanDefinitions(
AnnotationMetadata annotationMetadata, 
BeanDefinitionRegistry beanDefinitionRegistry) { 

//定义一个BeanDefinition
 RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(TestDao.class); 

//把自定义的bean定义导入到容器中 
beanDefinitionRegistry.registerBeanDefinition("testDao",rootBeanDefinition); }

}

通过ImportSelector功能导入进来的

public class TestServiceImpl {

 @Autowired
 private Testdao testDao;

public void testService() { 
    testDao.testDao(); 
        System.out.println("我是通过importSelector导入进来的service"); 
    }

}

通过ImportBeanDefinitionRegistar导入进来的

public class TestDao {

public void testDao() { 
    System.out.println("我是通过ImportBeanDefinitionRegistrar导入进来testDao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TestLog 一个是TestAspect 而TestLog 是依赖TestAspect的只有容器中有TestAspect组件才会加载TestLog

testLog组件依赖TestAspect组件

public class TestLog { }

testAspect组件

public class TestAspect { }

自动装配原理分析从@SpringbootApplication入手分析

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); }

}

然后我们分析RedisAutoConfiguration类

导入了三个组件

RedisTemplate
JedisConnectionConfiguration
StringRedisTemplate

@Configuration
@ConditionalOnClass(RedisOperations.class)
@EnableConfigurationProperties(RedisProperties.class)
@Import({ LettuceConnectionConfiguration.class,
 JedisConnectionConfiguration.class })         
public class RedisAutoConfiguration {

    //导入redisTemplate

    @Bean 
    @ConditionalOnMissingBean(name = "redisTemplate") 
    public RedisTemplate<Object, Object> redisTemplate( 
    RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {

    RedisTemplate<Object, Object> template = new RedisTemplate<>();

    template.setConnectionFactory(redisConnectionFactory); return template;

}

    @Bean 
    @ConditionalOnMissingBean 
    public StringRedisTemplate stringRedisTemplate(
         RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {

        StringRedisTemplate template = new StringRedisTemplate();

        template.setConnectionFactory(redisConnectionFactory);

        return template; 
    }

}

@Configuration 
@ConditionalOnClass({
 GenericObjectPool.class, 
JedisConnection.class, Jedis.class })
class JedisConnectionConfiguration extends RedisConnectionConfiguration {

private final RedisProperties properties;

private final List<JedisClientConfigurationBuilderCustomizer> builderCustomizers;

JedisConnectionConfiguration(RedisProperties properties,

ObjectProvider<RedisSentinelConfiguration> sentinelConfiguration, ObjectProvider<RedisClusterConfiguration> clusterConfiguration, ObjectProvider<List<JedisClientConfigurationBuilderCustomizer>> builderCustomizers) { super(properties, sentinelConfiguration, clusterConfiguration); this.properties = properties; this.builderCustomizers = builderCustomizers .getIfAvailable(Collections::emptyList);

}

@Bean
@ConditionalOnMissingBean(RedisConnectionFactory.class)
public JedisConnectionFactory redisConnectionFactory() throws UnknownHostException {         
  return createJedisConnectionFactory(); 
}

private JedisConnectionFactory createJedisConnectionFactory() { 
JedisClientConfiguration clientConfiguration = getJedisClientConfiguration(); 
if (getSentinelConfig() != null) { 
return new JedisConnectionFactory(
getSentinelConfig(), clientConfiguration);
 } if (getClusterConfiguration() != null) {

return new JedisConnectionFactory(getClusterConfiguration(), clientConfiguration); } 
return new JedisConnectionFactory(getStandaloneConfig(), clientConfiguration);

}

private JedisClientConfiguration getJedisClientConfiguration() {

JedisClientConfigurationBuilder builder = applyProperties( JedisClientConfiguration.builder()); 
RedisProperties.Pool pool = this.properties.getJedis().getPool(); 
if (pool != null) {

applyPooling(pool, builder); } 
if (StringUtils.hasText(this.properties.getUrl())) {

        customizeConfigurationFromUrl(builder); 
} customize(builder); 
    return builder.build();

}

private JedisClientConfigurationBuilder applyProperties(

JedisClientConfigurationBuilder builder) { if (this.properties.isSsl()) {

builder.useSsl(); } if (this.properties.getTimeout() != null) {

Duration timeout = this.properties.getTimeout();

builder.readTimeout(timeout).connectTimeout(timeout); } return builder;

}

private void applyPooling(RedisProperties.Pool pool, JedisClientConfiguration.JedisClientConfigurationBuilder builder) { builder.usePooling().poolConfig(jedisPoolConfig(pool)); }

private JedisPoolConfig jedisPoolConfig(RedisProperties.Pool pool) { JedisPoolConfig config = new JedisPoolConfig(); config.setMaxTotal(pool.getMaxActive()); config.setMaxIdle(pool.getMaxIdle()); config.setMinIdle(pool.getMinIdle()); if (pool.getMaxWait() != null) { config.setMaxWaitMillis(pool.getMaxWait().toMillis()); } return config;

}

}