zoukankan      html  css  js  c++  java
  • [rxjs] Shares a single subscription -- publish()

    If have an observable and you subscribe it twice, those tow subscritions have no connection. 

    console.clear();
    var Observable = Rx.Observable;
    var _id = 1;
    
    var source = Observable.create(function(Observe){
      var myId = _id++;
      Observe.onNext('Observable ' + myId);
      setTimeout(function(){
        Observe.onNext('Observable... ' + myId);
        Observe.onCompleted();
      }, 1000);
    });
    
    var subscrition1 = source.subscribe(function onNext(x){
      console.log('Observable 1: ' + x);
    });
    
    var subscrition2 = source.subscribe(function onNext(x){
      console.log('Observable 2: ' + x);
    });

    Result:

    /*"Observable 1: Observable 1"
    "Observable 2: Observable 2"
    "Observable 1: Observable... 1"
    "Observable 2: Observable... 2"*/

    publish():

    Returns an observable sequence that is the result of invoking the selector on a connectable observable sequence that shares a single subscription to the underlying sequence.

    console.clear();
    var Observable = Rx.Observable;
    var _id = 1;
    
    var source = Observable.create(function(Observe){
      var myId = _id++;
      Observe.onNext('Observable ' + myId);
      setTimeout(function(){
        Observe.onNext('Observable... ' + myId);
        Observe.onCompleted();
      }, 1000);
    });
    var published = source.publish();
    
    var subscrition1 = published.subscribe(function onNext(x){
      console.log('Observable 1: ' + x);
    });
    
    var subscrition2 = published.subscribe(function onNext(x){
      console.log('Observable 2: ' + x);
    });
    
    var connection = published.connect();

    Results:

    /*
    "Observable 1: Observable 1"
    "Observable 2: Observable 1"
    "Observable 1: Observable... 1"
    "Observable 2: Observable... 1"
    */

    You can see the result just have one single subscrition then.

    You can dispose the connection:

    connection.dispose();

    Results:

    /*"Observable 1: Observable 1"
    "Observable 2: Observable 1"*/

    There is a problem when you connect the published observables at different place.

    var Observable = Rx.Observable;
    var _id = 1;
    
    var source = Observable.create(function(Observe){
      var myId = _id++;
      Observe.onNext('Observable ' + myId);
      setTimeout(function(){
        Observe.onNext('Observable... ' + myId);
        Observe.onCompleted();
      }, 1000);
    });
    var published = source.publish();
    var connection = published.connect();
    
    var subscrition1 = published.subscribe(function onNext(x){
      console.log('Observable 1: ' + x);
    });
    
    var subscrition2 = published.subscribe(function onNext(x){
      console.log('Observable 2: ' + x);
    });
    
    //var connection = published.connect();

    Results:

    /*"Observable 1: Observable... 1"
    "Observable 2: Observable... 1"*/

    If we move the connect() funciton up before subscribe(). Then we missed the very first console.log(); It means connection is already start, but no one subscribe it yet.

    Therefore, we don't use publish() funciton alone, more than often we use publish().refCount() function together.

  • 相关阅读:
    微信小程序之项目的创建
    Java中的线程--多线程面试题
    Java中的线程--并发库中的集合
    Java中的线程--线程中的工具
    Java中的线程--Lock和Condition实现线程同步通信
    Linux指定用户运行程序
    CPU、内存、磁盘三者的关系
    shell从字符串中提取子串(正则表达式)
    ssh登录失败的常见问题分析
    正则表达式匹配不含有某字符串的行
  • 原文地址:https://www.cnblogs.com/Answer1215/p/4754960.html
Copyright © 2011-2022 走看看