一、创建用于属性承载的BeanDefinition
BeanDefiniton是一个接口,在Spring中存在三种实现:RootBeanDefinition、ChildBeanDefinition、GenericBeanDefiniton.三种实现均继承了AbstractBeanFactory,其中BeanDefinition是配置文件<bean>元素标签在容器中的内部表示形式。<bean>元素拥有class、scope、lazy-init等配置属性,BeanDefinition则提供了相应的beanClass、scope、lazyInit属性,BeanDefinition和<bean>中的属性是一一对应的。其中RootBeanDefinition是最常用的实现类,它对应一般性的<bean>元素标签,GenericBeanDefiniton是自2.5版本以后新加入的bean文件配置属性定义类,是一站式服务类。
在配置文件中可以定义父<bean>和子<bean>。父<bean>用RootBeanDefinition表示,而子<bean>用CgildBeanDefiniton表示,而没有父<bean>的,bea>就使用RootBeanDefinition表示。AbstractBeanDefinition对两者共同的类信息进行抽象。
Spring通过BeanDefinition将配置文件中的<bean>配置信息转换为容器的内部表示,并将这些BeanDefiniton注册到BeanDefinitonRegistry中。Spring容器的BeanDefinitonRegistry就像是Spring配置信息的内存数据库,主要是以map的形式保存,后续操作直接从BeanDefinitionRegistry中读取配置信息。
1、要解析属性首先要创建用于承载属性的实例,也就是创建GenericBeanDefiniton类型的实例。
2、解析各种属性
当我们创建了bean信息的承载实例后,变可以进行bean信息的各种属性解析了,首先我们进入parseBeanDefinitionAttribute方法。该方法是对element所有元素属性进行解析。
二、AbstractBeanDefinition属性
public abstract class AbstractBeanDefinition extends BeanMetadataAttributeAccessor implements BeanDefinition, Cloneable { /** * Constant for the default scope name: {@code ""}, equivalent to singleton * status unless overridden from a parent bean definition (if applicable). * bean的作用范围,对应bean属性scope */ public static final String SCOPE_DEFAULT = ""; /** * Constant that indicates no autowiring at all. * @see #setAutowireMode */ public static final int AUTOWIRE_NO = AutowireCapableBeanFactory.AUTOWIRE_NO; /** * Constant that indicates autowiring bean properties by name. * @see #setAutowireMode */ public static final int AUTOWIRE_BY_NAME = AutowireCapableBeanFactory.AUTOWIRE_BY_NAME; /** * Constant that indicates autowiring bean properties by type. * @see #setAutowireMode */ public static final int AUTOWIRE_BY_TYPE = AutowireCapableBeanFactory.AUTOWIRE_BY_TYPE; /** * Constant that indicates autowiring a constructor. * @see #setAutowireMode */ public static final int AUTOWIRE_CONSTRUCTOR = AutowireCapableBeanFactory.AUTOWIRE_CONSTRUCTOR; /** * Constant that indicates determining an appropriate autowire strategy * through introspection of the bean class. * @see #setAutowireMode * @deprecated as of Spring 3.0: If you are using mixed autowiring strategies, * use annotation-based autowiring for clearer demarcation of autowiring needs. */ @Deprecated public static final int AUTOWIRE_AUTODETECT = AutowireCapableBeanFactory.AUTOWIRE_AUTODETECT; /** * Constant that indicates no dependency check at all. * @see #setDependencyCheck */ public static final int DEPENDENCY_CHECK_NONE = 0; /** * Constant that indicates dependency checking for object references. * @see #setDependencyCheck */ public static final int DEPENDENCY_CHECK_OBJECTS = 1; /** * Constant that indicates dependency checking for "simple" properties. * @see #setDependencyCheck * @see org.springframework.beans.BeanUtils#isSimpleProperty */ public static final int DEPENDENCY_CHECK_SIMPLE = 2; /** * Constant that indicates dependency checking for all properties * (object references as well as "simple" properties). * @see #setDependencyCheck */ public static final int DEPENDENCY_CHECK_ALL = 3; /** * Constant that indicates the container should attempt to infer the * {@link #setDestroyMethodName destroy method name} for a bean as opposed to * explicit specification of a method name. The value {@value} is specifically * designed to include characters otherwise illegal in a method name, ensuring * no possibility of collisions with legitimately named methods having the same * name. * <p>Currently, the method names detected during destroy method inference * are "close" and "shutdown", if present on the specific bean class. */ public static final String INFER_METHOD = "(inferred)"; private volatile Object beanClass; private String scope = SCOPE_DEFAULT; private boolean abstractFlag = false; //是否延迟加载,对应bean属性lazy-init private boolean lazyInit = false; //自动注入模式,对应bean属性autowire private int autowireMode = AUTOWIRE_NO; //依赖检查 private int dependencyCheck = DEPENDENCY_CHECK_NONE; //用来表示一个bean的实例化依靠另一个bean先实例化,对应bean属性的depend-on private String[] dependsOn; //autowire-candicate属性设置为false,这样容器在查找自动装配对象时将不考虑bean,则它不会被考虑作为其他bean自动装配的候选者,但是该bean本身还是可以使用自动装配来注入其他bean的 //对应bean属性的autowire-candidate private boolean autowireCandidate = true; //自动装配时当出现多个bean候选者时,将作为首选者,对应bean属性primary private boolean primary = false; //用于记录Qualifier,对应子元素qualifier private final Map<String, AutowireCandidateQualifier> qualifiers = new LinkedHashMap<String, AutowireCandidateQualifier>(0); //允许访问非公开的构造器和方法,程序设置 private boolean nonPublicAccessAllowed = true; //是否以一种宽松的模式解析构造函数,默认为true private boolean lenientConstructorResolution = true; //对应bean属性的factory-bean private String factoryBeanName; //对应bean属性的factory-method private String factoryMethodName; //记录构造函数注入属性,对应bean属性constructor-arg private ConstructorArgumentValues constructorArgumentValues; //普通属性集合 private MutablePropertyValues propertyValues; //方法重写的持有者,记录lookup-method replaced-method元素 private MethodOverrides methodOverrides = new MethodOverrides(); //初始化方法,对应bean属性的init-method private String initMethodName; //销毁方法,对应bean属性的deatory-method private String destroyMethodName; //是否执行init-method程序设置 private boolean enforceInitMethod = true; //是否执行deatory-method程序设置 private boolean enforceDestroyMethod = true; //是否是用户定义的而不是应用程序本身定义的,创建AOP时候为true,程序设置 private boolean synthetic = false; //定义这个bean的应用,APPLICATION:用户;INFRASTRUCTURE:完全内部使用,与用户无关,SUPPORT:某些复杂配置的一部分 private int role = BeanDefinition.ROLE_APPLICATION; //bean的描述信息 private String description; //bean定义的资源 private Resource resource;