JAVA常用的单例模式 饿汉式、双检查锁、静态内部类、枚举
单例模式
1. 饿汉式
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| public class SingleTon {
private final static SingleTon INSTANCE = new SingleTon();
private SingleTon() {
}
public static SingleTon getInstance() {
return INSTANCE;
}
public void method() {
System.out.println("SingleTon");
}
}
|
2. 双检锁（懒汉式）
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| public class SingleTonDCL {
private volatile static SingleTonDCL singleton;
private SingleTonDCL() {
}
public static SingleTonDCL getInstance() {
if (singleton == null) {
synchronized (SingleTonDCL.class) {
if (singleton == null) {
singleton = new SingleTonDCL();
}
}
}
return singleton;
}
public void method() {
System.out.println("SingleTonDCL");
}
}
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3. 静态内部类（懒汉式）
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| public class SingleTonInnerClass {
private SingleTonInnerClass() {
}
public static SingleTonInnerClass getInstance() {
return SingleTonHolder.INSTANCE;
}
private static class SingleTonHolder {
private static final SingleTonInnerClass INSTANCE = new SingleTonInnerClass();
}
public void method() {
System.out.println("SingleTonInnerClass");
}
}
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4. 枚举模式（-）
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| public enum SingleTonEnum {
INSTANCE;
public void method() {
System.out.println("SingleTonEnum");
}
}
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参考链接
Java单例模式的7种写法中，为何用Enum枚举实现被认为是最好的方式？