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

<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

<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

<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

<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

<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

<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>