如何檢查組件的p：消息是否已存在？

Question

我的問題是，是否有任何方式可以檢查某個特定Primefaces組件是否已經存在消息，如果不存在，則只能爲該組件添加消息。

Answer 1

您可以通過FacesContext對象訪問特定組件的排隊消息。下面的代碼應該可以工作：

 FacesContext context = FacesContext.getCurrentInstance(); //obtain a reference to the FacesContext 
    String desiredClientId = "componentId"; //You should already have the client side id of the component you want to operate with 
    Iterator<FacesMessage> messageQueue = context.getMessages(desiredClientId); //Obtain an Iterator for a List of possible queued messages for the component id you've provided. 
    if(messageQueue.hasNext()){ 
     //the component has messages queued, do whatever you want 
     } 
     else{ 
     no messages, do whatever you want 
     }