更新 单例模式

JamesZBL · JamesZBL · commit 23d2273d5f48 · 2017-11-16T13:31:22.000+08:00
diff --git a/singleton/src/main/java/me/zbl/singleton/Director.java b/singleton/src/main/java/me/zbl/singleton/Director.java
@@ -0,0 +1,52 @@
+/**
+ * MIT License
+ * <p>
+ * Copyright (c) 2017 James
+ * <p>
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * <p>
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package me.zbl.singleton;
+
+/**
+ * “饿汉式” 的单例实现方式
+ * <p>
+ * 可以保证线程安全
+ */
+public class Director {
+
+  /**
+   * 静态的本类实例
+   */
+  private static final Director INSTANCE = new Director();
+
+  /**
+   * 私有化的构造方法保证不被其它类调用
+   */
+  private Director() {
+  }
+
+  /**
+   * 客户端调用获取单例实例
+   *
+   * @return 单例实例
+   */
+  public Director getInstance() {
+    return INSTANCE;
+  }
+}
diff --git a/singleton/src/main/java/me/zbl/singleton/LazyInitializationDirector.java b/singleton/src/main/java/me/zbl/singleton/LazyInitializationDirector.java
@@ -0,0 +1,55 @@
+/**
+ * MIT License
+ * <p>
+ * Copyright (c) 2017 James
+ * <p>
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * <p>
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package me.zbl.singleton;
+
+/**
+ * “懒汉式” 的单例模式
+ * <p>
+ * 内部类在被引用之前不会被类加载器加载，直到客户端调用的时候才被加载
+ * <p>
+ * 这个方案是线程安全的
+ */
+public class LazyInitializationDirector {
+
+  /**
+   * 私有构造方法
+   */
+  private LazyInitializationDirector() {
+  }
+
+  /**
+   * @return 单例实例
+   */
+  public LazyInitializationDirector getInstance() {
+    return InstanceHolder.INSTANCE;
+  }
+
+  /**
+   * 延迟加载，生成 {@link LazyInitializationDirector} 的实例
+   */
+  private static class InstanceHolder {
+
+    private static final LazyInitializationDirector INSTANCE = new LazyInitializationDirector();
+  }
+}
