spring 2.5 源码学习笔记： PropertyEditorRegistrySupport

PropertyEditorRegistrySupport
介绍：接口：PropertyEditorRegistry的基本实现，负责默认编辑器和自定义编辑器的管理，主要服务于基类 BeanWrapperImpl。
重要属性：

private Map defaultEditors;//装载默认编辑器

	private Map customEditors;//装载自定义编辑器

	private Set sharedEditors;//装载共享编辑器

	private Map customEditorCache;//自定义编辑器的缓存

主要方法：
取得默认属性编辑器：

public PropertyEditor getDefaultEditor(Class requiredType) {
		......
		return (PropertyEditor) this.defaultEditors.get(requiredType);/*取得给定属性类型的属性编辑器，defaultEditors 是以 requiredType为key ,PropertyEditor 为value的Map。这是通过下面的方法存放的。
*/
	}

注册一个自定义属性编辑器：

public void registerCustomEditor(Class requiredType, PropertyEditor propertyEditor) {
		registerCustomEditor(requiredType, null, propertyEditor);/*这里null表示类型为requiredType的属性均可使用propertyEditor编辑器*/
	}

注册完成在下面的方法：

	public void registerCustomEditor(Class requiredType, String propertyPath, PropertyEditor propertyEditor) {/*requiredType 或 propertyPath 决定那些属性使用该PropertyEditor */
		if (requiredType == null && propertyPath == null) {
			throw new IllegalArgumentException("Either requiredType or propertyPath is required");
		}/*最初需要定义一个存放自定义属性编辑器的Map*/
		if (this.customEditors == null) {
			this.customEditors = new LinkedHashMap(16);
		}/*[color=red]属性名称（名称，或是嵌套路径）不空，则propertyEditor只是针对该属性注册的[/color]*/
		if (propertyPath != null) {
			this.customEditors.put(propertyPath, new CustomEditorHolder(propertyEditor, requiredType));
			this.propertySpecificEditorsRegistered = true;
		}
		else {
[color=darkred]/*属性名称为空，则propertyEditor是针对属性类型为requiredType注册的*/[/color]
			this.customEditors.put(requiredType, propertyEditor);
			this.customEditorCache = null;
		}
	}

查找指定属性类型或是属性名称对应的编辑器：

	public PropertyEditor findCustomEditor(Class requiredType, String propertyPath) {
		......
		if (propertyPath != null) {
			if (this.propertySpecificEditorsRegistered) {
				/*优先查找指定属性对应的属性编辑器*/
				PropertyEditor editor = getCustomEditor(propertyPath, requiredType);
				if (editor == null) {
					List strippedPaths = new LinkedList();
					addStrippedPropertyPaths(strippedPaths, "", propertyPath);/*沿着属性嵌套路径查找，直到找到为止*/
					for (Iterator it = strippedPaths.iterator(); it.hasNext() && editor == null;) {
						String strippedPath = (String) it.next();
						editor = getCustomEditor(strippedPath, requiredType);
					}
				}
				if (editor != null) {
					return editor;
				}
			}
			if (requiredType == null) {
				requiredTypeToUse = getPropertyType(propertyPath);
			}
		}
		/* 若是没有指定属性，则找指定属性类型的对应编辑器*/
		return getCustomEditor(requiredTypeToUse);
	}

取得属性编辑器的方法：

	private PropertyEditor getCustomEditor(Class requiredType) {
		if (requiredType == null) {
			return null;
		}
		/* 首先直接按属性类型去获得 */
		PropertyEditor editor = (PropertyEditor) this.customEditors.get(requiredType);
		if (editor == null) {
			/* 尝试在缓冲编辑器map里获得*/
			if (this.customEditorCache != null) {
				editor = (PropertyEditor) this.customEditorCache.get(requiredType);
			}
			if (editor == null) {
				/*沿着属性路径去获得（它的超类） */
				for (Iterator it = this.customEditors.keySet().iterator(); it.hasNext() && editor == null;) {
					Object key = it.next();
					if (key instanceof Class && ((Class) key).isAssignableFrom(requiredType)) {
						editor = (PropertyEditor) this.customEditors.get(key);/* 为每种类型缓冲编辑器，以免以后重复查找*/
						if (this.customEditorCache == null) {
							this.customEditorCache = new HashMap();
						}
						this.customEditorCache.put(requiredType, editor);
					}
				}
			}
		}
		return editor;
	}

判断是否包含的数组/集合元素指定的编辑器：

	public boolean hasCustomEditorForElement(Class elementType, String propertyPath) {
		if (this.customEditors == null) {
			return false;
		}
		if (propertyPath != null && this.propertySpecificEditorsRegistered) {/*遍历注册器属性路径，若存在与指定属性匹配的属性路径，且该属性路径对应编辑器持有者拥有元素类型对应的编辑器则返回true*/
			for (Iterator it = this.customEditors.entrySet().iterator(); it.hasNext();) {
				Map.Entry entry = (Map.Entry) it.next();
				if (entry.getKey() instanceof String) {
					String regPath = (String) entry.getKey();
					if (PropertyAccessorUtils.matchesProperty(regPath, propertyPath)) {
						CustomEditorHolder editorHolder = (CustomEditorHolder) entry.getValue();
						if (editorHolder.getPropertyEditor(elementType) != null) {
							return true;
						}
					}
				}
			}
		}
		//若没有为该属性路径指定编辑器，则返回是否存在元素类型对应的属性编辑器
		return (elementType != null && this.customEditors.containsKey(elementType));
	}