Show Apex message at another page

Question

I want to display the message at another page when user click a button. Such as the user clicks button at Page A, then my action method will redirect user to Page B and show the message which is defined in the Page A controller.

Page A and Page B not use the same controller.

String pageHeaderReferer = ApexPages.currentPage().getHeaders().get('Referer'); 
if((pageHeaderReferer != null && pageHeaderReferer.containsIgnoreCase('Page1')) || isLtIE9()) 
{    
    ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.INFO, message)); 
} 

Be careful, using the above code in IE8 that there is no 'Referer' value.

Answer 1

The easiest way would be to pass the message as a parameter when redirecting the user, then have the second controller add that parameters content to the page.

Controller 1

public PageReference GoToPage2()
{
  ApexPages.PageReference pr = new ApexPages.PageReference(Page.Page2);
  pr.SetRedirect(true);
  pr.GetParameters().Put('message', 'Hello, World!');
  return pr;
}

Page 1

<apex:commandButton action="{!GoToPage2}" value="Page 2!"/>

Controller 2

public void Init()
{
  String message = '' + ApexPages.CurrentPage().GetParameters().Get('message');
  String pageHeaderReferer = ApexPages.currentPage().getHeaders().get('Referer'); 

  // Use the referrer parameter to only show the message when coming from Page 1
  if(pageHeaderReferer != null && pageHeaderReferer.containsIgnoreCase('Page1') && message != 'null')
  {
    ApexPages.CurrentPage().AddMessage(new ApexPages.Message(ApexPages.Severity.Info, message));
  }
}

Page 2

<apex:page controller="Page2Controller" action="{!Init}">
  <apex:pageMessages/>

The exact message syntax might be a little off, will double check it. It's one of those things I can remember when I'm coding but not when I'm just writing in the browser!