#[derive(Debug, Clone)] struct Work { //消息实体，存储消息 id: i32 } struct WorkMaster { //消息管理者属性 workers: Vec<Box<Worker>> //存储注册的接收者。每个接收者须实现Worker接口才能注册进。 } impl WorkMaster { fn register_worker(&mut self, worker: Box<Worker>) { //注册接收者 self.workers.push(worker); } fn dispatch_new_work(&self, work: Work) {//为接收者队列中的每个成员发送通知 for worker in &self.workers { worker.on_new_work(work.clone())//由于每个接收者都实现了Worker接口，此处可方便的调用实例化的接收者方法 } } } trait Worker { fn on_new_work(&self, work: Work);//self：消息接收者(列表) work：消息实体 } //通过构建不同的接收者，将消息发送与接收分离。 //接收者为彼此独立的结构体，而发送者维护一个存储了接收者的vec列表
//也可理解为，当WorkMaster状态发生改变时，所有依赖于他的对象都会接收到通知
struct LocalWorker {} impl Worker for LocalWorker { fn on_new_work(&self, work: Work) { println!("local worker receiver new work {:?}", work) } } struct RemoteWorker {} impl Worker for RemoteWorker { fn on_new_work(&self, work: Work) { println!("remote worker receive new work {:?}", work) } }
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn observer_mode_test() {
let mut master = WorkMaster{workers: Vec::new()};
let local_worker = LocalWorker{};
let remote_worker = RemoteWorker{};
master.register_worker(Box::new(local_worker));
master.register_worker(Box::new(remote_worker));
// local worker receiver new work Work { id: 1 }
// remote worker receive new work Work { id: 1 }
master.dispatch_new_work(Work{id: 1});
}
}
WorkMaster通过关联函数dispatch_new_work，通知接收者自己状态发生了改变。