死磕源码系列【springboot之Bindable源码解析】

怼烎@ 2022-12-19 09:29 124阅读 0赞

> Bindable是指可由Binder绑定的源（如：基本数据类型，java对象、List、数组等等），也可以理解为可以绑定到指定的属性配置的值。

##### Bindable属性源码 #####

public final class Bindable<T> { 
    	//默认注解空数组
    	private static final Annotation[] NO_ANNOTATIONS = { };
    	//要绑定项的类型
    	private final ResolvableType type;
    	//要绑定项的包装类型
    	private final ResolvableType boxedType;
    	//要绑定的数据值的提供者，是一个函数式接口
    	private final Supplier<T> value;
    	//可能影响绑定的任何关联注解
    	private final Annotation[] annotations;
    	//私有的构造函数，创建一个Bindable实例
    	private Bindable(ResolvableType type, ResolvableType boxedType, Supplier<T> value, Annotation[] annotations) { 
    		this.type = type;
    		this.boxedType = boxedType;
    		this.value = value;
    		this.annotations = annotations;
    	}
    	}

##### 获取不同数据类型的Bindable实例对象： #####

/** * 创建一个指定值及数据类型和指定值数据类型相同的Bindable实例对象 */
    	@SuppressWarnings("unchecked")
    	public static <T> Bindable<T> ofInstance(T instance) { 
    		Assert.notNull(instance, "Instance must not be null");
    		Class<T> type = (Class<T>) instance.getClass();
    		return of(type).withExistingValue(instance);
    	}
    
    	/** * 创建一个指定数据类型的Bindable实例对象 */
    	public static <T> Bindable<T> of(Class<T> type) { 
    		Assert.notNull(type, "Type must not be null");
    		return of(ResolvableType.forClass(type));
    	}
    
    	/** * 创建一个指定数据类型List的Bindable实例对象 */
    	public static <E> Bindable<List<E>> listOf(Class<E> elementType) { 
    		return of(ResolvableType.forClassWithGenerics(List.class, elementType));
    	}
    
    	/** * 创建一个指定数据类型Set的Bindalbe实例对象 */
    	public static <E> Bindable<Set<E>> setOf(Class<E> elementType) { 
    		return of(ResolvableType.forClassWithGenerics(Set.class, elementType));
    	}
    
    	/** * 创建一个指定类型为Map及指定key-value数据类型的Bindable实例对象 */
    	public static <K, V> Bindable<Map<K, V>> mapOf(Class<K> keyType, Class<V> valueType) { 
    		return of(ResolvableType.forClassWithGenerics(Map.class, keyType, valueType));
    	}
    
    	/** * 创建一个指定类型的Bindable实例对象 */
    	public static <T> Bindable<T> of(ResolvableType type) { 
    		Assert.notNull(type, "Type must not be null");
    		ResolvableType boxedType = box(type);
    		return new Bindable<>(type, boxedType, null, NO_ANNOTATIONS);
    	}

##### 将指定的数据类型转换为包装类型： #####

private static ResolvableType box(ResolvableType type) { 
    		Class<?> resolved = type.resolve();
    		if (resolved != null && resolved.isPrimitive()) { 
    			Object array = Array.newInstance(resolved, 1);
    			Class<?> wrapperType = Array.get(array, 0).getClass();
    			return ResolvableType.forClass(wrapperType);
    		}
    		if (resolved != null && resolved.isArray()) { 
    			return ResolvableType.forArrayComponent(box(type.getComponentType()));
    		}
    		return type;
    	}

##### 更新Bindable实例对象： #####

/** * 创建一个指定注解的更新Bindable实例对象 */
    	public Bindable<T> withAnnotations(Annotation... annotations) { 
    		return new Bindable<>(this.type, this.boxedType, this.value,
    				(annotations != null) ? annotations : NO_ANNOTATIONS);
    	}
    
    	/** * 创建一个存在指定值的更新Bindable实例对象 */
    	public Bindable<T> withExistingValue(T existingValue) { 
    		Assert.isTrue(
    				existingValue == null || this.type.isArray() || this.boxedType.resolve().isInstance(existingValue),
    				() -> "ExistingValue must be an instance of " + this.type);
    		Supplier<T> value = (existingValue != null) ? () -> existingValue : null;
    		return new Bindable<>(this.type, this.boxedType, value, this.annotations);
    	}
    
    	/** * 创建一个suppliedValue值提供者更新的Bindable实例对象 */
    	public Bindable<T> withSuppliedValue(Supplier<T> suppliedValue) { 
    		return new Bindable<>(this.type, this.boxedType, suppliedValue, this.annotations);
    	}

--------------------

GitHub地址：[https://github.com/mingyang66/spring-parent][https_github.com_mingyang66_spring-parent]

[https_github.com_mingyang66_spring-parent]: https://github.com/mingyang66/spring-parent