From 0e97ccce3b7001802d5b2c56991cf3648d04d49b Mon Sep 17 00:00:00 2001
From: xiangflight <xiangflight@foxmail.com>
Date: Tue, 10 Jul 2018 10:59:38 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E4=BA=86=E5=8D=95=E4=BE=8B?=
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---
 .DS_Store         | Bin 6148 -> 6148 bytes
 notes/设计模式.md |  24 +++++++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/.DS_Store b/.DS_Store
index 5aa9950dfa898a186d3dc8678c98aa2d3b436841..f8578f485bb4879458310b96d6cf38fd20b341f4 100644
GIT binary patch
delta 151
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delta 159
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zvV$|LQYUX`Q<G74sC8ff0S*Diki7i7R8CH1hXAk$!{iTaik6a$N{rf!CXBX>_KY5k
mfs8?nA&ilXQH;?LHB5{Unn4yyLn+3T$sX)mHnVg5<p%(bf*}O}

diff --git a/notes/设计模式.md b/notes/设计模式.md
index 72c1cd81..692e1b97 100644
--- a/notes/设计模式.md
+++ b/notes/设计模式.md
@@ -151,7 +151,29 @@ uniqueInstance 采用 volatile 关键字修饰也是很有必要的。`uniqueIns
 
 使用 volatile 可以禁止 JVM 的指令重排，保证在多线程环境下也能正常运行。
 
-（五）枚举实现
+
+（五）静态内部类实现
+
+这种实现方式的原理：当静态类加载时，静态内部类没有加载进内存。只有当外部调用`getInstance()`方法，静态内部类才会被创建，此时会实例化一个单例的对象，之后每次
+调用`getInstance()`都会获取相同的对象。此方法不需要同步。
+
+```java
+public class Singleton {
+
+    private Singleton() {
+    }
+
+    private static class SingletonHelper {
+    	private static final Singleton INSTANCE = new Singleton();
+    }
+
+    public static Singleton getUniqueInstance() {
+    	return SingletonHelper.INSTANCE;
+    }
+}
+```
+
+（六）枚举实现
 
 这是单例模式的最佳实践，它实现简单，并且在面对复杂的序列化或者反射攻击的时候，能够防止实例化多次。