说一说原子类AtomicReference的使用

• 原子性的赋值方法：compareAndSet()
• 在修改前，先判断旧值和新值是否相同

package org.springframework.cloud.client.discovery.event;

import java.util.concurrent.atomic.AtomicReference;

public class HeartbeatMonitor {
    private AtomicReference<Object> latestHeartbeat = new AtomicReference();

    public HeartbeatMonitor() {
    }

    public boolean update(Object value) {
        Object last = this.latestHeartbeat.get();
        return value != null && !value.equals(last) ? this.latestHeartbeat.compareAndSet(last, value) : false;
    }
}