mybatis metaObject

docs/Mybatis/核心处理层/Mybatis-MetaObject.md

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+# Mybatis MetaObject
+- Author: [HuiFer](https://github.com/huifer)
+- 源码位于:`org.apache.ibatis.reflection.MetaObject`
+```java
+/**
+ * @author Clinton Begin
+ */
+public class MetaObject {
+
+    /**
+     * 原始的数据对象,初始化时的对象
+     */
+    private final Object originalObject;
+    /**
+     * 对象包装
+     */
+    private final ObjectWrapper objectWrapper;
+    /**
+     * object 工厂
+     */
+    private final ObjectFactory objectFactory;
+    /**
+     * object
+     */
+    private final ObjectWrapperFactory objectWrapperFactory;
+    /**
+     * 反射工程
+     */
+    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;
+
+        // 根据object不同实例进行不同的实例化方式
+        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);
+        }
+    }
+
+    /**
+     * 获取value
+     * @param name 属性值名称
+     * @return
+     */
+    public Object getValue(String name) {
+        PropertyTokenizer prop = new PropertyTokenizer(name);
+        if (prop.hasNext()) {
+            MetaObject metaValue = metaObjectForProperty(prop.getIndexedName());
+            if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
+                // 判断是否是空的metaObject
+                return null;
+            } else {
+                return metaValue.getValue(prop.getChildren());
+            }
+        } else {
+            return objectWrapper.get(prop);
+        }
+    }
+
+    /**
+     * metaObject 设置属性值方法
+     * {name:value}
+     *
+     * @param name  属性值名称
+     * @param value 属性值
+     */
+    public void setValue(String name, Object value) {
+        PropertyTokenizer prop = new PropertyTokenizer(name);
+        if (prop.hasNext()) {
+            // 获取属性实例
+            MetaObject metaValue = metaObjectForProperty(prop.getIndexedName());
+            if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
+                if (value == null) {
+                    // value 空则返回
+                    // don't instantiate child path if value is null
+                    return;
+                } else {
+                    // 创建属性值
+                    metaValue = objectWrapper.instantiatePropertyValue(name, prop, objectFactory);
+                }
+            }
+
+            metaValue.setValue(prop.getChildren(), value);
+        } else {
+            objectWrapper.set(prop, value);
+        }
+    }
+
+ 
+}
+
+```