Flex4之DataGrid增删改同步数据库及页面数据示例总结

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代码 

<span style="font-size: medium;"><?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>  
</span> 

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
Java代码 

<span style="font-size: medium;">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);  
          
    }</span>  

DeleteTargetCalServlet
Java代码 

<span style="font-size: medium;">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");  
  
    }</span> 

AddTargetCalServlet
Java代码 

<span style="font-size: medium;">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);  
          
  
    }</span>  

UpdateTargetCalServlet
Java代码 

<span style="font-size: medium;">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);  
            }  
              
  
    }</span>

 
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
Java代码 

<span style="font-size: medium;">@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;  
    }  
  
}</span>