MyBatis之MetaObject

梦里梦外; 2022-05-08 06:40 215阅读 0赞

## MyBatis官方文档 ##

>  *  [MyBatis官方文档][MyBatis]
>  *  ORM框架

## 源码 ##

public class MetaObject { private final Object originalObject; private final ObjectWrapper objectWrapper; private final ObjectFactory objectFactory; private final ObjectWrapperFactory objectWrapperFactory; private final ReflectorFactory reflectorFactory; private MetaObject(Object object, ObjectFactory objectFactory, ObjectWrapperFactory objectWrapperFactory, ReflectorFactory reflectorFactory) { this.originalObject = object; this.objectFactory = objectFactory; this.objectWrapperFactory = objectWrapperFactory; this.reflectorFactory = reflectorFactory; // instanceof运算符是用来在运行时指出对象是否是特定类的一个实例 if (object instanceof ObjectWrapper) { this.objectWrapper = (ObjectWrapper) object; } else if (objectWrapperFactory.hasWrapperFor(object)) { this.objectWrapper = objectWrapperFactory.getWrapperFor(this, object); } else if (object instanceof Map) { this.objectWrapper = new MapWrapper(this, (Map) object); } else if (object instanceof Collection) { this.objectWrapper = new CollectionWrapper(this, (Collection) object); } else { this.objectWrapper = new BeanWrapper(this, object); } } public static MetaObject forObject(Object object, ObjectFactory objectFactory, ObjectWrapperFactory objectWrapperFactory, ReflectorFactory reflectorFactory) { if (object == null) { return SystemMetaObject.NULL_META_OBJECT; } else { return new MetaObject(object, objectFactory, objectWrapperFactory, reflectorFactory); } } public ObjectFactory getObjectFactory() { return objectFactory; } public ObjectWrapperFactory getObjectWrapperFactory() { return objectWrapperFactory; } public ReflectorFactory getReflectorFactory() { return reflectorFactory; } public Object getOriginalObject() { return originalObject; } public String findProperty(String propName, boolean useCamelCaseMapping) { return objectWrapper.findProperty(propName, useCamelCaseMapping); } public String[] getGetterNames() { return objectWrapper.getGetterNames(); } public String[] getSetterNames() { return objectWrapper.getSetterNames(); } public Class<?> getSetterType(String name) { return objectWrapper.getSetterType(name); } public Class<?> getGetterType(String name) { return objectWrapper.getGetterType(name); } public boolean hasSetter(String name) { return objectWrapper.hasSetter(name); } public boolean hasGetter(String name) { return objectWrapper.hasGetter(name); } public Object getValue(String name) { PropertyTokenizer prop = new PropertyTokenizer(name); // PropertyTokenizer实现了Iterator接口 if (prop.hasNext()) { MetaObject metaValue = metaObjectForProperty(prop.getIndexedName()); if (metaValue == SystemMetaObject.NULL_META_OBJECT) { return null; } else { return metaValue.getValue(prop.getChildren()); } } else { return objectWrapper.get(prop); } } public void setValue(String name, Object value) { PropertyTokenizer prop = new PropertyTokenizer(name); if (prop.hasNext()) { MetaObject metaValue = metaObjectForProperty(prop.getIndexedName()); if (metaValue == SystemMetaObject.NULL_META_OBJECT) { if (value == null && prop.getChildren() != null) { // don't instantiate child path if value is null // 提前结束函数【metaValue.setValue(prop.getChildren(), value);不执行】 return; } else { metaValue = objectWrapper.instantiatePropertyValue(name, prop, objectFactory); } } metaValue.setValue(prop.getChildren(), value); } else { objectWrapper.set(prop, value); } } public MetaObject metaObjectForProperty(String name) { Object value = getValue(name); return MetaObject.forObject(value, objectFactory, objectWrapperFactory, reflectorFactory); } public ObjectWrapper getObjectWrapper() { return objectWrapper; } public boolean isCollection() { return objectWrapper.isCollection(); } public void add(Object element) { objectWrapper.add(element); } public <E> void addAll(List<E> list) { objectWrapper.addAll(list); } }

[MyBatis]: http://www.mybatis.org/mybatis-3/zh/getting-started.html