标签：style blog java color for div
单例模式是一种最常见的设计模式，校招中如果要进大公司，必须透彻的掌握单例模式，总结了常见的一些单例模式
首先是最简单的恶汉模式,恶汉模式是一种最简单的单例模式
/**
* 恶汉模式
*/
public class SingleTon {
private static final SingleTon instance = new SingleTon();
private SingleTon(){
}
public static SingleTon getInstance() {
return instance;
}
}
其实是懒汉加载模式，最简单的懒汉加载模式如下
public class SingleTon {
private static SingleTon instance = null ;
private SingleTon(){
}
public static SingleTon getInstance() {
if (instance == null) {
instance = new SingleTon();
}
return instance;
}
}
但上述懒汉模式是线程不安全的，可以对其进行加锁
public class SingleTon {
private static SingleTon instance = null ;
private SingleTon(){
}
public static synchronized SingleTon getInstace(){
if (instances == null ) {
return instances = new SingleTon();
}
return instances;
}
}
或者双重加锁模式
public class SingleTon {
private static SingleTon instance = null ;
private SingleTon(){
}
public static SingleTon getInstance(){
if (instances == null) {
synchronized (SingleTon.class) {
instances = new SingleTon();
}
}
return instances;
}
}
单例模式还可以用内部类来实现
public class SingleTon {
public static class SingleTonHolder{
private static SingleTon instance = new SingleTon();
}
public SingleTon() {
}
public static SingleTon getInstance() {
return SingleTonHolder.instance;
}
}
看看大牛Jon Skeet是怎么写单例的 (c#版)
public sealed class Singleton
{
Singleton()
{
}
public static Singleton Instance
{
get
{
return Nested.instance;
}
}
class Nested
{
// Explicit static constructor to tell C# compiler
// not to mark type as beforefieldinit
static Nested()
{
}
internal static readonly Singleton instance = new Singleton();
}
}
有任何疑问可联系本人huwei08@baidu.com
标签：style blog java color for div
原文地址：http://www.cnblogs.com/huwei0814/p/3840387.html
