doc: Spring-MethodOverride

README.md

@@ -73,6 +73,9 @@
 * [Spring 元数据](/docs/Spring/clazz/Spring-Metadata.md)
 * [Spring 条件接口](/docs/Spring/clazz/Spring-Conditional.md)
 
+* [Spring MultiValueMap](/docs/Spring/clazz/Spring-MultiValueMap.md)
+* [Spring MethodOverride](/docs/Spring/clazz/Spring-MethodOverride.md)
+
 
 ### Spring5 新特性
 

docs/Spring/clazz/Spring-MethodOverride.md

@@ -0,0 +1,293 @@
+# Spring MethodOverride
+- Author: [HuiFer](https://github.com/huifer)
+- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
+
+
+- `org.springframework.beans.factory.support.MethodOverride`
+    - `org.springframework.beans.factory.support.LookupOverride`
+    - `org.springframework.beans.factory.support.ReplaceOverride`
+- `org.springframework.beans.factory.support.MethodOverrides`
+
+
+
+## MethodOverride
+- MethodOverride 方法重载类
+
+
+
+在`MethodOverride`定义了下面三个属性
+
+1. 方法名称
+2. 是否重载
+3. 源
+
+```java
+public abstract class MethodOverride implements BeanMetadataElement {
+
+   /**
+    * 方法名称
+    */
+   private final String methodName;
+
+   /**
+    * 是否重载
+    */
+   private boolean overloaded = true;
+
+   /**
+    * 源
+    */
+   @Nullable
+   private Object source;
+}
+```
+
+- 定义了一个抽象方法, 交由子类实现
+
+```java
+public abstract boolean matches(Method method);
+```
+
+
+
+
+
+类图
+
+![MethodOverride](/images/spring/MethodOverride.png)
+
+
+
+- 在Spring中有两种可以重写的机制(XML)
+
+  1. `lookup-method` 标签
+
+     ```xml
+     <lookup-method name="" bean=""/>
+     ```
+
+     
+
+  2. `replaced-method` 标签
+
+     ```xml
+     <replaced-method name="" replacer=""/>
+     ```
+
+     
+
+相对应的两个类如类图所示
+
+
+
+
+
+## LookupOverride
+
+- `org.springframework.beans.factory.support.LookupOverride`
+- lookup-method 标签对应的实体对象
+
+属性列表
+
+1. beanName
+2. method
+
+```java
+@Nullable
+private final String beanName;
+
+@Nullable
+private Method method;
+```
+
+
+
+### matches
+
+比较方法
+
+1. method是否直接相等
+ 1. method 名称是否相同
+ 2. 是否需要重载
+3. 是不是 ABSTRACT 方法
+ 4. 参数列表长度是否等于0
+
+```java
+	@Override
+	public boolean matches(Method method) {
+		if (this.method != null) {
+			// 通过 equals 判断
+			return method.equals(this.method);
+		}
+		else {
+			// 1. method 名称是否相同
+			// 2. 是否需要重载
+			// 3. 是不是 ABSTRACT 方法
+			// 4. 参数列表长度是否等于0
+			return (method.getName().equals(getMethodName()) && (!isOverloaded() ||
+					Modifier.isAbstract(method.getModifiers()) || method.getParameterCount() == 0));
+		}
+	}
+
+```
+
+
+
+
+
+## ReplaceOverride
+
+- `org.springframework.beans.factory.support.ReplaceOverride`
+
+```java
+/**
+ * 实现 MethodReplacer 接口的bean name
+ * @see MethodReplacer
+ */
+private final String methodReplacerBeanName;
+
+/**
+ * 标签 arg-type 数据
+ */
+private final List<String> typeIdentifiers = new LinkedList<>();
+```
+
+
+
+- 一个例子
+
+```XML
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	   xmlns="http://www.springframework.org/schema/beans"
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
+	<bean id="apple" class="org.source.hot.spring.overview.ioc.bean.lookup.Apple">
+		<replaced-method replacer="methodReplacerApple" name="hello" >
+			<arg-type>String</arg-type>
+		</replaced-method>
+
+	</bean>
+
+	<bean id="methodReplacerApple" class="org.source.hot.spring.overview.ioc.bean.lookup.MethodReplacerApple">
+
+	</bean>
+
+</beans>
+```
+
+
+
+methodReplacerBeanName 对应`org.springframework.beans.factory.support.MethodReplacer` 的实现类
+
+typeIdentifiers 对应标签 arg-type  的属性值
+
+
+
+构造方法
+
+
+
+```java
+public ReplaceOverride(String methodName, String methodReplacerBeanName) {
+   super(methodName);
+   Assert.notNull(methodName, "Method replacer bean name must not be null");
+   this.methodReplacerBeanName = methodReplacerBeanName;
+}
+```
+
+
+
+methodName 通过父类进行设置
+
+
+
+
+
+### matches
+
+
+
+```java
+@Override
+public boolean matches(Method method) {
+   // 方法名称是否相同
+   if (!method.getName().equals(getMethodName())) {
+      return false;
+   }
+   // 是否重载
+   if (!isOverloaded()) {
+      // Not overloaded: don't worry about arg type matching...
+      return true;
+   }
+   // If we get here, we need to insist on precise argument matching...
+   // 类型标识数量是否和参数列表是否不相同
+   if (this.typeIdentifiers.size() != method.getParameterCount()) {
+      return false;
+   }
+   // 获取参数类型列表
+   Class<?>[] parameterTypes = method.getParameterTypes();
+   for (int i = 0; i < this.typeIdentifiers.size(); i++) {
+      String identifier = this.typeIdentifiers.get(i);
+      // 判断 方法参数的类型是否在类型标识列表中
+      if (!parameterTypes[i].getName().contains(identifier)) {
+         return false;
+      }
+   }
+   return true;
+}
+```
+
+
+
+
+
+
+
+## MethodOverrides
+
+- `org.springframework.beans.factory.support.MethodOverrides`
+
+- 重载方法对象
+
+- 存储所有重载的方法列表(set结构)
+
+```java
+	private final Set<MethodOverride> overrides = new CopyOnWriteArraySet<>();
+```
+
+
+
+
+
+几个方法
+
+
+
+1. 添加 MethodOverride
+
+   ```java
+   public void addOverride(MethodOverride override) {
+      this.overrides.add(override);
+   }
+   
+   public void addOverrides(@Nullable MethodOverrides other) {
+   		if (other != null) {
+   			this.overrides.addAll(other.overrides);
+   		}
+   }
+   ```
+
+1. 获取 MethodOverride
+
+   ```java
+   @Nullable
+   public MethodOverride getOverride(Method method) {
+      MethodOverride match = null;
+      for (MethodOverride candidate : this.overrides) {
+         if (candidate.matches(method)) {
+            match = candidate;
+         }
+      }
+      return match;
+   }
+   ```