坦克大战（一期）-设计模式-享元模式

src/main/java/com/msb/flyweight/Main.java

@@ -0,0 +1,66 @@
+package com.msb.flyweight;/**
+ * @Author bingor
+ * @Date 2022/10/14 19:40
+ * @Description: com.msb.flyweight
+ * @Version: 1.0
+ */
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+
+/**
+ *@ClassName Main
+ *@Description TODO
+ *@Author bingor
+ *@Date 2022/10/14 19:40
+ *@Version 3.0
+ */
+public class Main {
+
+    public static void main(String[] args) {
+
+        BulletPool pool = new BulletPool();
+
+        for (int i=0; i<10 ; i++) {
+            Bullet bullet = pool.getBullet();
+            System.out.println(bullet);
+        }
+    }
+
+}
+
+class Bullet {
+    private UUID id = UUID.randomUUID();
+    private boolean live = false;
+
+    @Override
+    public String toString() {
+        return "Bullet{" +
+                "id=" + id +
+                '}';
+    }
+
+    public boolean isLive() {
+        return live;
+    }
+}
+
+class BulletPool {
+
+    private List<Bullet> bullets = new ArrayList<>();
+
+    {
+        for (int i=0; i<5; i++) {
+            bullets.add(new Bullet());
+        }
+    }
+
+    public Bullet getBullet() {
+        for (Bullet bullet : bullets) {
+            if( ! bullet.isLive()) return bullet;
+        }
+        return new Bullet();
+    }
+
+}

src/test/java/CommonTest.java

@@ -48,4 +48,18 @@ public class CommonTest {
         return true;
     }
 
+    @Test
+    public void testString() {
+        String s1 = "abc";
+        String s2 = "abc";
+        String s3 = new String("abc");
+        String s4 = new String("abc");
+
+        System.out.println(s1 == s2);   //true, 因为都是从字符串常量池取出的,指向的是同一个对象
+        System.out.println(s1 == s3);   //false 因为两个对象地址不一样
+        System.out.println(s3 == s4);   //false 因为两个对象地址不一样
+        System.out.println(s3.intern() == s1);  //true  s3.intern() 指的是该地址指向内部指向常量池的对象
+        System.out.println(s3.intern() == s4.intern()); //true
+    }
+
 }