單例<件>模式
1.急切實(shí)例化 <餓漢>
public class Singleton {
private static Singleton uniqueInstance = new Singleton();
private Singleton() {}
public static Singleton getInstance() {
return uniqueInstance;
}
}
2.同步getInstance()方法
public class Singleton{
private SingleTone() {}
public static synchronized Singleton getInstance() {
if (uniqueInstance == null) {
uniqueInstance = new Singleton();
}
return uniqueInstance;
}
}
3.雙重檢查枷鎖 <性能比同步getInstance()好, 需要JDK Java5或以上>
public class Singleton {
private volatile static Singleton uniqueInstance;
private Singleton() {}
public static Singleton getInstance() {
if (uniqueInstance == null) {
synchronized (Singleton.class) {
if (uniqueInstance == null) {
uniqueInstance = new Singleton();
}
}
}
}
}
