Spring boot源码分析-AnnotationConfigApplicationContext非web环境下的启动容器（2）

来源：互联网发布：app文件上传java 接口编辑：程序博客网时间：2024/06/10 04:51

Spring boot源码分析-AnnotationConfigApplicationContext非web环境下的启动容器（2）

首先我们看容器的类图

1.首先该类间接继承了AbstractApplicationContext（Spring容器最重要的抽象类，就有了容器最终要的一些功能）
2.该类还实现了AnnotationConfigRegistry 注解扫描注册接口就是基于注解的容器实现了读取spring注解加载容器的功能

容器启动，构造方法

首先我们看类的构造方法，主要做了以下几个工作
1. AnnotatedBeanDefinitionReader BeanDefinition解析器用来解析带注解的bean
2. ClassPathBeanDefinitionScanner bean的扫描器用来扫描类
3. 注册解析传入的配置类（使用类配置的方式进行解析）
4. 调用容器的refresh方法初始化容器

public class AnnotationConfigApplicationContext extends GenericApplicationContext implements AnnotationConfigRegistry {    private final AnnotatedBeanDefinitionReader reader;    private final ClassPathBeanDefinitionScanner scanner;    public AnnotationConfigApplicationContext() {        //关键代码  里面有注解的BeanDefinitionreader        this.reader = new AnnotatedBeanDefinitionReader(this);        //bean扫描器        this.scanner = new ClassPathBeanDefinitionScanner(this);        logger.info(this.getBeanFactory());    }    public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {        this();        //关键代码   注册配置的类对象   （当配置类上有@Conditional注解且为matches方法返回false的时候  好像这个类就不注册了）        register(annotatedClasses);        refresh();    }}

在看他的父类的构造器创建了DefaultListableBeanFactory bean工厂

    public GenericApplicationContext() {        this.beanFactory = new DefaultListableBeanFactory();    }

我们现在对于容器的类型和大致的执行过程有了一个了解知道容器启动的时候做了哪几个大的工作

AnnotatedBeanDefinitionReader Bean解析器的分析

先看构造的源码

this.reader = new AnnotatedBeanDefinitionReader(this);

    public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {        this(registry, getOrCreateEnvironment(registry));    }    public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {        Assert.notNull(registry, "BeanDefinitionRegistry must not be null");        Assert.notNull(environment, "Environment must not be null");        this.registry = registry;        //Conditional注解评估器        this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);        //这个时关键   注册AnnotationConfigProcessor        AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);    }

注解的条件判断器ConditionEvaluator 该方法在初始化的时调用，当配置的类上有@Conditional注解并且返回false的时候容器就不处理该类

AnnotationConfigApplicationContext

public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {        ······        register(annotatedClasses);        ······    }}public void register(Class<?>... annotatedClasses) {        Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified");        this.reader.register(annotatedClasses);}

AnnotatedBeanDefinitionReader

public void register(Class<?>... annotatedClasses) {        for (Class<?> annotatedClass : annotatedClasses) {            registerBean(annotatedClass);        }}public void registerBean(Class<?> annotatedClass, String name, Class<? extends Annotation>... qualifiers) {        AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);        //解析beanClass的@Conditional注解，如果有注解返回false 容器就停止处理        if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {            return;        }        ······}

再看代码这是整个容器的关键，调用了registerAnnotationConfigProcessors方法该方法的作用
注册和解析spring注解相关的post processors
该方法被调用有两个地方
- 1.在spring使用AnnotationConfigBeanDefinitionParser解析xml文件的时候也就是配置annotation-config的时候
- 2.启动在AnnotationConfigApplicationContext容器的时候

AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);

AnnotationConfigUtils

    public static final String AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME =            "org.springframework.context.annotation.internalAutowiredAnnotationProcessor";public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {        registerAnnotationConfigProcessors(registry, null);    }public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(            BeanDefinitionRegistry registry, Object source) {        ······        //注册ConfigurationClassPostProcessor        if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {            //1.在spring使用AnnotationConfigBeanDefinitionParser解析xml文件的时候  也就是配置annotation-config的时候            //2.启动在AnnotationConfigApplicationContext容器的时候            RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);            def.setSource(source);            beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));        }        //自动注入 注册AutowiredAnnotationBeanPostProcessor        if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {            RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);            def.setSource(source);            //org.springframework.context.annotation.internalAutowiredAnnotationProcessor            beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));        }        ······        return beanDefs;    }

我们再看beanfactory注册了ConfigurationClassPostProcessor类，我们看看这个类的类图以及作用
- 我们可以看到ConfigurationClassPostProcessor实现了BeanDefinitionRegistryPostProcessor接口,该接口在
  AbstractApplicationContext的refresh()方法中会被nvokeBeanFactoryPostProcessors(beanFactory)方法调用,就是在容器激活的时候被调用
在看看ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry方法,由代码可以知道这个类解析了spring使用@Configuration配置方式的bean

    @Override    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {        RootBeanDefinition iabpp = new RootBeanDefinition(ImportAwareBeanPostProcessor.class);        iabpp.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);        registry.registerBeanDefinition(IMPORT_AWARE_PROCESSOR_BEAN_NAME, iabpp);        //注册了ConfigurationBeanPostProcessor        RootBeanDefinition ecbpp = new RootBeanDefinition(EnhancedConfigurationBeanPostProcessor.class);        ecbpp.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);        registry.registerBeanDefinition(ENHANCED_CONFIGURATION_PROCESSOR_BEAN_NAME, ecbpp);        int registryId = System.identityHashCode(registry);        if (this.registriesPostProcessed.contains(registryId)) {            throw new IllegalStateException(                    "postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);        }        if (this.factoriesPostProcessed.contains(registryId)) {            throw new IllegalStateException(                    "postProcessBeanFactory already called on this post-processor against " + registry);        }        this.registriesPostProcessed.add(registryId);        //处理@Configuration的bean        processConfigBeanDefinitions(registry);    }

在看看@SpringBootApplication的组合注解就知道bean是怎么被加载的了

ClassPathBeanDefinitionScanner Bean解析器的分析

ClassPathBeanDefinitionScanner提供了包扫描路径的方式启动容器，中间的解析方式和使用类文件的配置是一样的

ApplicationContext context=new AnnotationConfigApplicationContext("com.mitix.spring.context.expb");

protected Set<BeanDefinitionHolder> doScan(String... basePackages) {        Assert.notEmpty(basePackages, "At least one base package must be specified");        Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<BeanDefinitionHolder>();        for (String basePackage : basePackages) {            //寻找候选的BeanDefinition            //注：注解在匹配的时候会递归的   会找这个注解的父注解            Set<BeanDefinition> candidates = findCandidateComponents(basePackage);            for (BeanDefinition candidate : candidates) {                //scope注解设置beandefinition的scope属性                ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);                candidate.setScope(scopeMetadata.getScopeName());                String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);                //如果满足AbstractBeanDefinition类型，就设置名字，就是上面获取到的那个                if (candidate instanceof AbstractBeanDefinition) {                    /*                     * 1.设置了beandefinition的默认需要的那些属性                     *                      */                    postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);                }                //如果是实现注解的beandefinition,然后把一堆注解解析成属性放进去，什么依赖啊什么的                if (candidate instanceof AnnotatedBeanDefinition) {                    AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);                }                //检查注册的候选bean                if (checkCandidate(beanName, candidate)) {                    BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);                    //这里可能创建起来的是一个代理                    definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);                    beanDefinitions.add(definitionHolder);                    //把代理注册到registory上，就是注册到工厂里                    registerBeanDefinition(definitionHolder, this.registry);                }            }        }        return beanDefinitions;    }

总结

AnnotationConfigApplicationContext类提供了另外一种启动spring容器的方式，而不是使用传统的xml文件进行配置

具体详细的启动过程，可以查看spring的源码相关的问题

阅读全文

0 0