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notes/设计模式.md

@@ -2631,7 +2631,6 @@ public class SubSystem {
 public class Facade {
     private SubSystem subSystem = new SubSystem();
 
-
     public void watchMovie() {
         subSystem.turnOnTV();
         subSystem.setCD("a movie");
@@ -2657,7 +2656,79 @@ public class Client {
 
 ### 意图
 
-利用共享的方式来支持大量的对象，这些对象一部分内部状态是相同的，而另一份状态可以变化。
+利用共享的方式来支持大量细粒度的对象，这些对象一部分内部状态是相同的。
+
+### 类图
+
+- Flyweight：享元对象
+- IntrinsicState：内部状态，相同的项元对象共享
+- ExtrinsicState：外部状态
+
+<div align="center"> <img src="../pics//d52270b4-9097-4667-9f18-f405fc661c99.png"/> </div><br>
+
+### 实现
+
+```java
+public interface Flyweight {
+    void doOperation(String extrinsicState);
+}
+```
+
+```java
+public class ConcreteFlyweight implements Flyweight {
+
+    private String intrinsicState;
+
+    public ConcreteFlyweight(String intrinsicState) {
+        this.intrinsicState = intrinsicState;
+    }
+
+    @Override
+    public void doOperation(String extrinsicState) {
+        System.out.println("Object address: " + System.identityHashCode(this));
+        System.out.println("IntrinsicState: " + intrinsicState);
+        System.out.println("ExtrinsicState: " + extrinsicState);
+    }
+}
+```
+
+```java
+import java.util.HashMap;
+
+public class FlyweightFactory {
+
+    private HashMap<String, Flyweight> flyweights = new HashMap<>();
+
+    Flyweight getFlyweight(String intrinsicState) {
+        if (!flyweights.containsKey(intrinsicState)) {
+            Flyweight flyweight = new ConcreteFlyweight(intrinsicState);
+            flyweights.put(intrinsicState, flyweight);
+        }
+        return flyweights.get(intrinsicState);
+    }
+}
+```
+
+```java
+public class Client {
+    public static void main(String[] args) {
+        FlyweightFactory factory = new FlyweightFactory();
+        Flyweight flyweight1 = factory.getFlyweight("aa");
+        Flyweight flyweight2 = factory.getFlyweight("aa");
+        flyweight1.doOperation("x");
+        flyweight2.doOperation("y");
+    }
+}
+```
+
+```html
+Object address: 1163157884
+IntrinsicState: aa
+ExtrinsicState: x
+Object address: 1163157884
+IntrinsicState: aa
+ExtrinsicState: y
+```
 
 ### JDK