Flex4之DataGrid增删改同步数据库及页面数据示例总结

于 2011-10-03 11:50:45 发布
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分类专栏： Flex 文章标签： 数据库 json java
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有关Flex的DataGrid文章的确不少，都是零零碎碎的，目前还没有发现有个完整的例子供网友参考，这次我花了两天时间做了下Flex关于DataGrid一个指标数据管理系统，当然设计到的mxml会很多，大都是与DataGrid相关，我就抽取最常用的DataGrid的增删改同步数据库及页面数据来讲解

首先整理下思路，首先无论是删除还是修改，必须得获取当前行所在的记录，那么可以设置个全局变量，当DataGrid的itemClick事件出发时将选中的行赋给全局变量

[Bindable]public var acItemsSelected:Object;;

//事件方法

 protected function myGrid_itemClickHandler(event:ListEvent):void
   {
    acItemsSelected = myGrid.selectedItem; 
   }

这样的话就可以获得了当前选中的对象了

如果删除和修改的话，通常传到后台的肯定含有对象的ID项，那么这个ID是怎么获取的呢，通过acItemsSelected.xxxId能获取，那么这个xxxId必须是在DataGrid中有，设置为不显示就好了，例如我就是这么做的

 <mx:DataGridColumn visible="false" dataField="targetCalId" />

这样的话，要更改的数据等都能通过ID传到后台查询相应对象更改删除了，接下来的事是比较重要的，如果光删除数据库是不行的，页面数据也要保持同步，关于dataGrid也没有好的刷新方法，所以你上网一搜，可能有的人会告诉你对于删除这样做：dataArray.removeItemAt(myGrid.selectedIndex);

增加这样做：dataArray.addItemAt(obj,0);

修改这样做：dataArray.setItemAt(obj,myGrid.selectedIndex);

这里说的dataArray是指的是DataGrid的DataProvider的值集合【当然肯定得声明称全局变量】

这样的写法呢可能你觉得，哎，是对的，其实不然，这并没有真正起到作用，对于FLEX来说缓存是相当大的，不行的话你通过这个修改行记录的属性后，再点这行记录的属性编辑页面发现值根本没改，所以所没有进行二次查询数据库了，利用的是缓存。即便是你调用了初始化查询数据库的那个方法，也是不行的，还是有缓存，最好的做法就是，抛弃上面的三种写法，只需要两步就可以实现刷新，第一初始化DataGrid的那个方法请求必须是URLRequest的，添加一个参数类似于

var u:URLVariables=new URLVariables("temp="+Math.random());

当然不一定非要是temp什么名字都行，然后在返回操作成功提示后调用这个初始化方法，你会发现真的起作用了。

其实建议关于URLRequest传参数的最好带上这个参数，也不费事，可以在很多场合下解决缓存不更新问题

说了这么多其实就是先做好个思想准备，理清思路，下面我就贴上我的一段代码

mxml文件

<?xml version="1.0" encoding="utf-8"?>
<s:TitleWindow xmlns:fx="http://ns.adobe.com/mxml/2009" 
			   xmlns:s="library://ns.adobe.com/flex/spark" 
			   xmlns:mx="library://ns.adobe.com/flex/mx" width="668" height="326" 
			   creationComplete="initComponent()" 	
			   title="指标计量单位"
			   fontSize="15"
			   close="closeWindow()">  
	
	<s:layout>
		<s:VerticalLayout />
	</s:layout>
	<fx:Declarations>
		<mx:StringValidator id="sval_1" source="{targetTypeName}" property="text" 
							tooShortError="字符串太短了，请输入最少4个字符. " 
							tooLongError="字符串太长了，请输入最长20个字符. " 
							minLength="4" maxLength="20" 
							trigger="{myButton}" triggerEvent="click" 
							/>
		<mx:StringValidator id="sval_2" source="{targetCal}" property="text" 
							tooShortError="字符串太短了，请输入最少4个字符. " 
							tooLongError="字符串太长了，请输入最长20个字符. " 
							minLength="4" maxLength="20" 
							trigger="{myButton}" triggerEvent="click" 
							/>
	</fx:Declarations>
	
	<fx:Script>
		<![CDATA[
			import com.adobe.serialization.json.JSON;
			
			import mx.collections.ArrayCollection;
			import mx.controls.Alert;
			import mx.events.CloseEvent;
			import mx.events.ListEvent;
			import mx.managers.PopUpManager;
			import mx.rpc.events.ResultEvent;
			import mx.utils.URLUtil;
			import mx.validators.Validator;
			
			import org.osmf.utils.URL;  
			[Bindable]public static var mainApp:DataCenterTargetPreserve = null;     
			[Bindable]public var gsMyString:String;        
			[Bindable]public var gnMyNumber:Number;        
			[Bindable]public var acItemsSelected:Object;
			[Bindable]
			public var dataArray:ArrayCollection; 
			
			private function initComponent():void  
			{  
				var u:URLVariables=new URLVariables("temp="+Math.random());
				var r:URLRequest=new URLRequest();
				r.data=u;
				r.method=URLRequestMethod.POST;
				r.url=mainApp.urls+"/findTargetCal.do";
				
				var l:URLLoader=new URLLoader();
				l.load(r);
				l.addEventListener(Event.COMPLETE, comp2);
				
			}  
			function comp2(e:Event):void
			{
				var l:URLLoader=URLLoader(e.target);
				var array:Array=JSON.decode(String(l.data)) as Array;
				dataArray=new ArrayCollection(array);
				myGrid.dataProvider=dataArray;
			} 
			private function closeWindow():void  
			{  
				PopUpManager.removePopUp(this);  
			}//closeWindow  
			private function showFinalSelection(oEvent:Event):void  
			{  
				//mainApp.tiFinalSelection.text = oEvent.target.selectedItem.album;  
			}//showFinalSelection  

			protected function button1_clickHandler(event:MouseEvent):void
			{
				PopUpManager.removePopUp(this);  
				
			}

			protected function button2_clickHandler(event:MouseEvent):void
			{
				
				var all:Array=Validator.validateAll([sval_1,sval_2]);
				if(all.length==0){
				var v:URLVariables=new URLVariables("targetTypeName="+targetTypeName.text+"&targetCal="+targetCal.text+"&temp="+Math.random());
				var r:URLRequest=new URLRequest();
				r.url=mainApp.urls+"/addTargetCal.do";
				r.method=URLRequestMethod.POST;
				r.data=v;
				var l:URLLoader=new URLLoader();
				l.load(r);
				l.addEventListener(Event.COMPLETE,comp);
				}else{
				  Alert.show("新增失败");
				}
				
			}
			private function comp(e:Event):void{
				var l:URLLoader = URLLoader(e.target);  
				var o:Object=URLUtil.stringToObject(l.data,";",true);
			    if(o.result=="add"){
				  Alert.show("新增成功");
				  var obj:Object=(JSON.decode(o.datas) as Object);
				  //dataArray.addItemAt(obj,0);
				  Alert.show(obj.targetCalId);
				}
				initComponent();
			
			}

			private function myClick(evt:CloseEvent):void{
				//Alert.show("本次要删除的为"+mainDataGrid.selectedIndex);
				if(evt.detail==Alert.YES){
					//Alert.show(acItemsSelected.getItemAt(0).targetId);
					var v:URLVariables = new URLVariables("id="+acItemsSelected.targetCalId+"&temp="+Math.random());
					var r:URLRequest = new URLRequest();  
					r.url =mainApp.urls+"/deleteTargetCal.do" ;  
					r.method = URLRequestMethod.POST;  
					r.data=v;
					var l:URLLoader = new URLLoader();  		
					l.load(r);  
					
					//dataArray.removeItemAt(myGrid.selectedIndex);
					l.addEventListener(Event.COMPLETE,comp1); //注册请求完成后 响应获取数据事件方法 
					
				}
			}
			private function comp1(e:Event):void  
			{  
				var l:URLLoader = URLLoader(e.target);
				var o:Object = URLUtil.stringToObject(l.data, ";", true);
				if(o.result=="delete"){
					Alert.show("删除成功！","友情提示");
				}
				initComponent();
				
			} 
			protected function button3_clickHandler(event:MouseEvent):void
			{
				if(myGrid.selectedItem==null){
					Alert.show("请选择一项进行删除","友情提示");
				}else{
					var dlg_obj:Object=Alert.show("确认删除吗？", "友情提示！", Alert.YES|Alert.NO,null,myClick);
				}
			}


			protected function button4_clickHandler(event:MouseEvent):void
			{
				
				if(myGrid.selectedItem==null){
					Alert.show("请选择一项进行修订!","友情提示");
				}else{
					var v:URLVariables = new URLVariables("targetTypeName="+targetTypeName.text+"&targetCal="+targetCal.text+"&id="+acItemsSelected.targetCalId);
					var r:URLRequest = new URLRequest();  
					r.url =mainApp.urls+"/updateTargetCal.do";  
					r.method = URLRequestMethod.POST;  
					r.data = v;  
					var l:URLLoader = new URLLoader();  		
					l.load(r);  
					l.addEventListener(Event.COMPLETE,comp3); //注册请求完成后 响应获取数据事件方法 
				}
			}
			private function comp3(e:Event):void  
			{  
				
				var l:URLLoader = URLLoader(e.target);  
				var o:Object = URLUtil.stringToObject(l.data, ";", true);		
				if(o.result=="update"){
					Alert.show("更新成功！","友情提示");
					var obj:Object=(JSON.decode(o.datas) as Object);
					//dataArray.setItemAt(obj,myGrid.selectedIndex);
				}else{
					Alert.show("操作失败！","友情提示");
				}
				initComponent();
			}  

			protected function myGrid_itemClickHandler(event:ListEvent):void
			{
				acItemsSelected =myGrid.selectedItem;
			}

		]]>
	</fx:Script>
	<mx:Form width="651" height="282">
		<mx:DataGrid width="616" height="160" id="myGrid" itemClick="myGrid_itemClickHandler(event)">
			<mx:columns>
				<mx:DataGridColumn headerText="计量名称" dataField="targetTypeName"/>
				<mx:DataGridColumn headerText="计量符号" dataField="targetCal"/>
				<mx:DataGridColumn visible="false" dataField="targetCalId" />
			</mx:columns>
		</mx:DataGrid>
		<mx:HBox>
			<s:Label  width="33"/>
			<mx:FormItem label="计量名称" >
				<s:TextInput id="targetTypeName"/>
			</mx:FormItem>
			<mx:FormItem label="计量符号" >
				<s:TextInput id="targetCal"/>
			</mx:FormItem>
			<mx:FormItem >
				<s:Button label="新增" id="myButton" click="button2_clickHandler(event)" />
			</mx:FormItem>
			
		</mx:HBox>
		<mx:FormItem >
		</mx:FormItem>
		
		<mx:HBox>
			<s:Label  width="250"/>
			<mx:FormItem >
				<s:Button label="删除" click="button3_clickHandler(event)"/>
			</mx:FormItem>
			<mx:FormItem >
				<s:Button label="修改" click="button4_clickHandler(event)"/>
			</mx:FormItem>
			<mx:FormItem >
				<s:Button label="刷新"/>
			</mx:FormItem>
			<mx:FormItem >
				<s:Button label="关闭" click="button1_clickHandler(event)"/>
			</mx:FormItem>
		</mx:HBox>
		
	</mx:Form>
</s:TitleWindow>

 

关于上面这个程序的mainApp就不用管它，它只是主应用程序而已，细心的可以发现这个是个弹出窗口程序

 关于这个程序的三个Servletet处理类【只贴上关键代码】

FindTargetCalServlet

 

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		TTargetCalDAO dao=new TTargetCalDAO();
		List<TTargetCal> cals=dao.findAll();
		JSONArray json = JSONArray.fromObject(cals);
		String datas = json.toString();
		System.out.println(datas);
		System.out.println(datas);
		response.setCharacterEncoding("UTF-8");
		response.getWriter().write(datas);
		
	}

 

DeleteTargetCalServlet

 

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		TTargetCalDAO dao = new TTargetCalDAO();
		String id = request.getParameter("id");
		if (DataOptUtils.isNotNull(id)) {
			TTargetCal rr = dao.findById(Integer.valueOf(id));
			dao.delete(rr);
		}
		response.setCharacterEncoding("UTF-8");
		response.getWriter().write("result=delete");

	}

 

 

AddTargetCalServlet

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		    request.setCharacterEncoding("UTF-8");
		    TTargetCalDAO dao=new TTargetCalDAO();
		    String targetCal=request.getParameter("targetCal");
		    String targetTypeName=request.getParameter("targetTypeName");
		    TTargetCal cal=new TTargetCal();
		    cal.setTargetCal(targetCal);
		    cal.setTargetTypeName(targetTypeName);
		    dao.save(cal);
			TTargetCal re =dao.findById(dao.findLastId());
			JSONObject json = JSONObject.fromObject(re);
			String datas = json.toString();
			response.getWriter().write("result=add;datas=" + datas);
		

	}

 

 

UpdateTargetCalServlet

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		 request.setCharacterEncoding("UTF-8");
			response.setCharacterEncoding("UTF-8");
			TTargetCalDAO dao = new TTargetCalDAO();
			String targetTypeName = request.getParameter("targetTypeName");
			String targetCal = request.getParameter("targetCal");
			String id = request.getParameter("id");
			if (DataOptUtils.isNotNull(id)) {
				TTargetCal rr = dao.findById(Integer.valueOf(id));
				if(DataOptUtils.isNotNull(targetCal)){
					rr.setTargetCal(targetCal);
				}
				if(DataOptUtils.isNotNull(targetTypeName)){
					rr.setTargetTypeName(targetTypeName);
				}
				dao.merge(rr);
				TTargetCal tc = dao.findById(rr.getTargetCalId());
				JSONObject json = JSONObject.fromObject(tc);
				String datas = json.toString();
				response.getWriter().write("result=update;datas=" + datas);
			}
			

	}

 这里的DataOptUtils是我写的一个数据处理类，判断是否为空什么的

 还有就是TTargetCal

@Entity
@Table(name = "t_target_cal", catalog = "sxtele")
public class TTargetCal implements java.io.Serializable {

	// Fields

	private Integer targetCalId;
	private String targetCal;
	private String targetTypeName;

	// Constructors

	/** default constructor */
	public TTargetCal() {
	}

	/** minimal constructor */
	public TTargetCal(String targetCal) {
		this.targetCal = targetCal;
	}

	/** full constructor */
	public TTargetCal(String targetCal, String targetTypeName) {
		this.targetCal = targetCal;
		this.targetTypeName = targetTypeName;
	}

	// Property accessors
	@Id
	@GeneratedValue
	@Column(name = "Target_cal_id", unique = true, nullable = false)
	public Integer getTargetCalId() {
		return this.targetCalId;
	}

	public void setTargetCalId(Integer targetCalId) {
		this.targetCalId = targetCalId;
	}

	@Column(name = "Target_cal", nullable = false, length = 50)
	public String getTargetCal() {
		return this.targetCal;
	}

	public void setTargetCal(String targetCal) {
		this.targetCal = targetCal;
	}

	@Column(name = "Target_type_name", length = 50)
	public String getTargetTypeName() {
		return this.targetTypeName;
	}

	public void setTargetTypeName(String targetTypeName) {
		this.targetTypeName = targetTypeName;
	}

}

 

 

 

 

 

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