java設計模式之單例模式（雙重加鎖懶漢）

package src.test.java.com.pbc.singleton;

/**
 * （雙重加鎖懶漢）單例模式
 * @author qiu_y
 *
 */
public class DoubleLockSingleton {
 private static DoubleLockSingleton doubleLockSingleton = null;
 /**
  * 私有構造器
  */
 private DoubleLockSingleton() {}
 /**
  * 雙重加鎖懶漢單例
  * 懶加載，線程安全，效率高
  */
 public static DoubleLockSingleton getInstince() {
  if(null == doubleLockSingleton) {
   synchronized (DoubleLockSingleton.class) {
    if (null == doubleLockSingleton) {
     doubleLockSingleton = new DoubleLockSingleton();
    }
   }
   
  }
  return doubleLockSingleton;
 }
}