極客書

Flex - RPC Services

Flex提供RPC服務來向客戶端提供伺服器端數據。Flex對伺服器端數據提供了相當數量的控制。

  • 使用Flex-RPC服務，我們可以定義要在伺服器端執行的用戶操作。

  • Flex-RPC服務可以與任何伺服器端技術集成。

  • Flex-RPC服務之一提供了對壓縮二進位數據的內置支持，可以通過有線傳輸，而且速度非常快。

Flex提供了以下三種類型的RPC服務

Sr.No RPC Service & Description
1

http服務

<mx:HTTPService>標記用於表示MXML文件中的HTTPService對象。當您調用HTTPService對象的send（）方法時，它會向指定的URL發出一個HTTP請求，並返回一個HTTP響應。您還可以使用HTTP HEAD、OPTIONS、TRACE和DELETE方法。
2

網絡服務

<mx:WebService>用於訪問與SOAP兼容的web服務的操作。
3

遠程對象

標記<mx:RemoteObject>用於表示MXML文件中的HTTPService對象。此標記允許您使用動作消息格式（AMF）編碼訪問Java對象的方法。

我們將詳細討論HTTP服務。我們將使用放置在伺服器上的XML源文件，並通過HTTP服務在客戶端訪問它。

Items.xml

<items>
   <item name = "Book" description = "History of France"></item>
   <item name = "Pen" description = "Parker Pen"></item>
   <item name = "Pencil" description = "Stationary"></item>
<items>

HTTPService Declaration

現在聲明一個HTTPService並將上面文件的url傳遞給它

<fx:Declarations>
   <mx:HTTPService id = "itemRequest" 
   url = "http://www.tutorialspoint.com/flex/Items.xml" />
</fx:Declarations>

RPC Call

調用itemRequest.send（）方法並將itemRequest webservice的lastResult對象中的值綁定到Flex UI組件。

...
itemRequest.send();
...
<mx:DataGrid id = "dgItems" height = "80%" width = "75%" 
   dataProvider = "{itemRequest.lastResult.items.item}">
   <mx:columns>
      <mx:DataGridColumn headerText = "Name" dataField = "name" />
      <mx:DataGridColumn headerText = "Description" dataField = "description" />
   </mx:columns>
</mx:DataGrid>

RPC Service Call Example

現在，讓我們按照步驟在Flex應用程式中測試RPC服務;

Step Description
1 Create a project with a name HelloWorld under a package com.tutorialspoint.client as explained in the Flex - Create Application chapter.
2 Modify HelloWorld.mxml as explained below. Keep rest of the files unchanged.
3 Compile and run the application to make sure business logic is working as per the requirements. 

<?xml version = "1.0" encoding = "utf-8"?>
<s:Application xmlns:fx = "http://ns.adobe.com/mxml/2009" 
   xmlns:s = "library://ns.adobe.com/flex/spark" 
   xmlns:mx = "library://ns.adobe.com/flex/mx" 
   minWidth = "500" minHeight = "500" creationComplete = "init(event)">
   
   <fx:Style source = "/com/tutorialspoint/client/Style.css" />
   <fx:Script>
      <![CDATA[
         import mx.events.FlexEvent;
         import mx.rpc.events.FaultEvent;
         import mx.rpc.events.ResultEvent;

         protected function init(event:FlexEvent):void {
            itemRequest.send();				
         }
      ]]>
   </fx:Script>
   
   <fx:Declarations>
      <mx:HTTPService id = "itemRequest" 
         url = "http://www.tutorialspoint.com/flex/Items.xml" />
   </fx:Declarations>
   
   <s:BorderContainer width = "630" height = "480" id = "mainContainer" 
      styleName = "container">
      <s:VGroup width = "100%" height = "100%" gap = "10" 
         horizontalAlign = "center" verticalAlign = "middle">
         <s:Label id = "lblHeader" text = "RPC Service Demonstration" 
            fontSize = "40" color = "0x777777" styleName = "heading" />
         
         <s:Panel id = "parentPanel" title = "Using RPC Services"  
            width = "500" height = "200" >
            <s:layout>
               <s:VerticalLayout  gap = "10" 
                  verticalAlign = "middle" horizontalAlign = "center" />
            </s:layout>						
            
            <mx:DataGrid id = "dgItems" height = "80%" width = "75%" 
               dataProvider = "{itemRequest.lastResult.items.item}">
               
               <mx:columns>
                  <mx:DataGridColumn headerText = "Name" dataField = "name" />
                  <mx:DataGridColumn headerText = "Description" 
                     dataField = "description" />
               </mx:columns>
            </mx:DataGrid>
         </s:Panel>	
      </s:VGroup>	 
   </s:BorderContainer>	
</s:Application>

完成所有更改後，讓我們以正常模式編譯並運行應用程式，就像我們在flex-create application一章中所做的那樣。如果您的應用程式一切正常，它將產生以下結果：[聯機試用]