Java单例模式饿汉式和懒汉式的实现
1、饿汉式 package singleton;/**
* 饿汉式单例
* @author 蒋明原
*
*/
public class HungrySingleton {
/**jvm保证instance只被初始化一次*/
private static HungrySingleton instance = new HungrySingleton();
/**阻止外部使用new实例化对象*/
private HungrySingleton(){
}
/**
* 获取实例
* @return 独一的instance
*/
public static HungrySingleton getInstance() {
return instance;
}
}2、懒汉式
package singleton;
/**
* 懒汉式单例
* @author 蒋明原
*
*/
public class LazySingleton {
/**
* 阻止外界使用new实例化对象
*/
private LazySingleton() {
}
/**
* 只有在挪用getInstance()时此类才会被装载
* 在SingletonKerriganF.java中说了然加载挨次
*/
private static class SingletonHolder {
/**
* 对象实例,jvm保证只初始化一次
*/
static final LazySingleton INSTANCE = new LazySingleton();
}
/**
* 获取实例
* @return 返回独一实例
*/
Java单例模式饿汉式和懒汉式的实现
public LazySingleton getInstance() {</p> return SingletonHolder.INSTANCE;}
}3、懒汉式单例内部类加载挨次
package singleton;
/**
* 实现单例访谒Kerrigan的第六次考试考试
* @author IcyFenix
* @see http://www.javaeye.com/topic/575052
*/
public class SingletonKerriganF {
private static String arg = null;
private static class SingletonHolder {
/**
* 单例对象实例
*/
static final SingletonKerriganF INSTANCE = new SingletonKerriganF();
}
public static SingletonKerriganF getInstance() {
return SingletonHolder.INSTANCE;
}
public SingletonKerriganF() {
System.out.println("Kerrigan get arg:" + getArg());
System.out.println("Kerrigan created!");
}
public static String getArg() {
return arg;
}
public static void setArg(String arg) {
SingletonKerriganF.arg = arg;
}
public static void main(String[] args) {
System.out.println("SingletonKerriganF was loaded,but SingletonKerriganF$SingletonHolder don't");
SingletonKerriganF.setArg("this maybe some config files etc....");
SingletonKerriganF.getInstance();
}
}
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