class文件：
public abstract class Singleton extends Enum{
private Singleton(String s, int i){
super(s, i);
}
protected abstract void read();
protected abstract void write();
public static Singleton[] values(){
Singleton asingleton[];
int i;
Singleton asingleton1[];
System.arraycopy(asingleton = ENUM$VALUES, 0, asingleton1 = new Singleton[i = asingleton.length], 0, i);
return asingleton1;
}
public static Singleton valueOf(String s) {
return (Singleton)Enum.valueOf(singleton/Singleton, s);
}
Singleton(String s, int i, Singleton singleton){
this(s, i);
}
public static final Singleton INSTANCE;
private static final Singleton ENUM$VALUES[];
static {
INSTANCE = new Singleton("INSTANCE", 0){
protected void read(){
System.out.println("read");
}
protected void write(){
System.out.println("write");
}
};
ENUM$VALUES = (new Singleton[] {
INSTANCE
});
}
}
- 类的修饰abstract，所以没法实例化，反射也无能为力。关于线程安全的保证，其实是通过类加载机制来保证的，我们看看INSTANCE的实例化时机，是在static块中，JVM加载类的过程显然是线程安全的。对于防止反序列化生成新实例的问题还不是很明白，一般的方法我们会在该类中添加上如下方法，不过枚举中也没有显示的写明该方法。技术博客大总结
//readResolve to prevent another instance of Singleton
private Object readResolve(){
return INSTANCE;
}
