分析Ext.DataView结合Ext.Panel是怎么样输出数据


Ext.DataView 一种使用定制的模板布局和格式展示数据的机制。 DataView使用一个Ext.XTemplate作为其内部的模板机制, 并被绑定到一个Ext.data.Store, 这样当store中的数据发生变化时视图将自动同步以反应变化。 视图也内建了对许多可能发生的通用事件的处理,包含项目被单击、双击、鼠标滑过、鼠标移出等等, 同时也有一个内建的选择模型(selection model)。为了使用这些特性,必须为DataView提供一个itemSelector配置项, 用来决定与哪个节点配合使用。

   以下是使用Ext.DataView和Ext.Panel输出数据

view source print ?
01 <script type="text/javascript">
02           
03         Ext.onReady(function() {
04   
05             // create the data store
06             varstore =newExt.data.ArrayStore({
07                 fields: [
08                    { name:'company'},
09                    { name:'price', type:'float'},
10                    { name:'change', type:'float'},
11                    { name:'pctChange', type:'float'},
12                    { name:'lastChange', type:'date', dateFormat:'n/j h:ia' }
13                ]
14             });
15   
16   
17             // sample static data for the store
18             varmyData = [
19         ['3m Co', 71.72, 0.02, 0.03,'9/1 12:00am'],
20         ['Alcoa Inc', 29.01, 0.42, 1.47,'9/1 12:00am'],
21         ['Altria Group Inc', 83.81, 0.28, 0.34,'9/1 12:00am'],
22         ['American Express Company', 52.55, 0.01, 0.02,'9/1 12:00am'],
23         ['American International Group, Inc.', 64.13, 0.31, 0.49,'9/1 12:00am'],
24         ['AT&T Inc.', 31.61, -0.48, -1.54,'9/1 12:00am'],
25         ['Boeing Co.', 75.43, 0.53, 0.71,'9/1 12:00am'],
26         ['Caterpillar Inc.', 67.27, 0.92, 1.39,'9/1 12:00am'],
27         ['Citigroup, Inc.', 49.37, 0.02, 0.04,'9/1 12:00am'],
28         ['E.I. du Pont de Nemours and Company', 40.48, 0.51, 1.28,'9/1 12:00am'],
29         ['Exxon Mobil Corp', 68.1, -0.43, -0.64,'9/1 12:00am'],
30         ['General Electric Company', 34.14, -0.08, -0.23,'9/1 12:00am'],
31         ['General Motors Corporation', 30.27, 1.09, 3.74,'9/1 12:00am'],
32         ['Hewlett-Packard Co.', 36.53, -0.03, -0.08,'9/1 12:00am'],
33         ['Honeywell Intl Inc', 38.77, 0.05, 0.13,'9/1 12:00am'],
34         ['Intel Corporation', 19.88, 0.31, 1.58,'9/1 12:00am'],
35         ['International Business Machines', 81.41, 0.44, 0.54,'9/1 12:00am'],
36         ['Johnson & Johnson', 64.72, 0.06, 0.09,'9/1 12:00am'],
37         ['JP Morgan & Chase & Co', 45.73, 0.07, 0.15,'9/1 12:00am'],
38         ['McDonald\'s Corporation', 36.76, 0.86, 2.40,'9/1 12:00am'],
39         ['Merck & Co., Inc.', 40.96, 0.41, 1.01,'9/1 12:00am'],
40         ['Microsoft Corporation', 25.84, 0.14, 0.54,'9/1 12:00am'],
41         ['Pfizer Inc', 27.96, 0.4, 1.45,'9/1 12:00am'],
42         ['The Coca-Cola Company', 45.07, 0.26, 0.58,'9/1 12:00am'],
43         ['The Home Depot, Inc.', 34.64, 0.35, 1.02,'9/1 12:00am'],
44         ['The Procter & Gamble Company', 61.91, 0.01, 0.02,'9/1 12:00am'],
45         ['United Technologies Corporation', 63.26, 0.55, 0.88,'9/1 12:00am'],
46         ['Verizon Communications', 35.57, 0.39, 1.11,'9/1 12:00am'],
47         ['Wal-Mart Stores, Inc.', 45.45, 0.73, 1.63,'9/1 12:00am']
48     ];
49   
50       // manually load local data
51       store.loadData(myData);
52   
53       vartpl =newExt.XTemplate('<tpl for=".">',
54                                             '<div class="thumb-wrap">',
55                                                '<table><tr>',
56                                                '<td>{company}</td><td>{price}</td><td>{change}</td><td>{pctChange}</td><td>{lastChange}</td>',
57                                               '</tr></table>',
58                                             '</div>',
59                                         '</tpl>',
60                                        '<div class="x-clear"></div>');
61   
62       varpanel =newExt.Panel({
63                 id:'images-view',
64                 frame:true,
65                 width: 535,
66                 autoHeight:true,
67                 collapsible:true,
68                 layout:'fit',
69                 autoHeight:true,
70                 title:'Simple DataView',
71   
72                 items:newExt.DataView({
73                     store: store,
74                     tpl: tpl,
75                     autoHeight:true,
76                     multiSelect:true,
77                     overClass:'x-view-over',
78                     itemSelector:'div.thumb-wrap',
79                     emptyText:'No images to display'
80                 })
81             });
82       panel.render(document.body);
83   
84     });
85 </script>

   以下是上面的代码执行之后在IE8中的截图

分析Ext.DataView结合Ext.Panel是怎么样输出数据_第1张图片

                                                                                             图(1)
    下面来简单分析下, EXTJS是怎么样呈现这样的界面,其大致执行流程,用以加深对EXTJS的理解,也便于自己日后写扩展。下面的截图是用StarUML画出上面的代码所涉及到有关"类"和组件之间的关系图

分析Ext.DataView结合Ext.Panel是怎么样输出数据_第2张图片

                                                                                                      图(2)

view source print ?
01 var panel = new Ext.Panel({
02           //...
03           items:newExt.DataView({
04                     store: store,
05                     tpl: tpl,
06                     autoHeight:true,
07                     multiSelect:true,
08                     overClass:'x-view-over',
09                     itemSelector:'div.thumb-wrap',
10                     emptyText:'No images to display'
11          })
12  });

当实例化Panel时候会先实例化传入的object literal中的items。根据图(2)中Ext.DataView中继承关系和之前一篇文章Extjs- Ext.extend函数的使用知道 Ext.DataView 中传入的object literal中将会传入至Ext.Component的constructor中。

view source print ?
01 Ext.Component = function(config){
02  //...
03   this.getId();
04  //...
05 }
06   
07 Ext.Component.AUTO_ID = 1000;
08   
09 Ext.extend(Ext.Component, Ext.util.Observable, {
10  //...
11  getId :function(){
12         returnthis.id || (this.id ='ext-comp-'+ (++Ext.Component.AUTO_ID));
13  }
14  //...
15 });

      执行Ext.Component的constructor方法时会调用this.getId()方法,在上面的代码中没有传入id值。因此得知实例化items的组件的id编号为ext-comp-1001。用firebug查看EXJS生成的HTML可以很清楚的看到

分析Ext.DataView结合Ext.Panel是怎么样输出数据_第3张图片

                                                                                                          图(3)

     Ext.Component的constructor方法会调用this.initComponent()方法。当实例化items时候根据图(2),则会先调用Ext.DataView中的initComponent方法,随后会根据继承关系会向上回溯直至Ext.Component的initComponet,当执行Ext.Component中的initComponent方法之后又会向下回溯至Ext.BoxComponet中的initComponent方法,当执行完Ext.BoxComponent中的initComponent方法又会返回Ext.DataView中继续执行initComponent。中间的细节在此跳过,可以自己查看源码。

     实例化items完后,接下来就会实例化Panel类,同之前过程一模一样,也是会调用Ext.Component的constructor方法。根据图(2)中Ext.Panel的继承关系会依次调用相应的类的initComponent方法。实例化完Panel类时,因为传入了id值为'images-view'这样的话panel的id值将不会自动产生,而是'images-view'。在firebug中查看

                                                                                                           图(4)

 两个组件都已经实例化完成了,接下来会执行panel.render(document.body)。根据图(2)得知会调用Ext.Component的render方法。 

view source print ?
01 Ext.extend(Ext.Component, Ext.util.Observable, {
02      //...
03   render :function(container, position){
04     if(!this.rendered &&this.fireEvent('beforerender',this) !==false){
05              //...
06   
07             this.onRender(this.container, position ||null);
08              
09              //...
10              
11              this.afterRender(this.container);
12             
13              //...
14      }
15      returnthis;  
16    }
17   //...
18 });

     当执行到this.onRender(this.container, position || null)时,根据图(2) 则会调用Ext.Panel中的onRender方法。Ext.Panel.supreclass.onRnder.call(this,ct,position) 则会调用Ext.Component中的onRender方法。调用完之后会返回继续执行Ext.Panel中的onRender方法

view source print ?
01 Ext.Panel = Ext.extend(Ext.Container, {
02   
03      //...
04      
05   onRender :function(ct, position){
06   
07    Ext.Panel.superclass.onRender.call(this, ct, position);
08      
09    //...
10   
11  }
12   
13  //...
14   
15 });
16   
17 Ext.extend(Ext.Component, Ext.util.Observable, {
18   
19   //...
20   
21    onRender :function(ct, position){
22      //..
23    }
24 //....
25 ));

当程序执行到this.afterRender(this.container)时候,查看此时生成EXTJS产生的HTML代码

this.container.dom.innerHTML

view source print ?
01 <divid=images-viewclass=" x-panel"
02   <divclass=x-panel-tl> 
03        <divclass=x-panel-tr> 
04          <divclass=x-panel-tc> 
05            <divstyle="MozUserSelect: none; KhtmlUserSelect: none"id=ext-gen4class="x-panel-header x-unselectable"unselectable="on"
06              <divid=ext-gen9class="x-tool x-tool-toggle"> </div>
07               <spanclass=x-panel-header-text></span>
08            </div>
09          </div>
10       </div>
11  </div
12  <divid=ext-gen5class=x-panel-bwrap> 
13     <divclass=x-panel-ml> 
14       <divclass=x-panel-mr> 
15         <divid=ext-gen8class=x-panel-mc> 
16           <divid=ext-gen6class=x-panel-body></div>
17         </div>
18       </div>
19     </div
20     <divid=ext-gen7class="x-panel-bl x-panel-nofooter"
21       <divclass=x-panel-br> 
22         <divclass=x-panel-bc></div>
23       </div>
24     </div>
25  </div>
26 </div>

this.container.dom.outerHTML

view source print ?
01 <bodyid=ext-gen3class=" ext-ie ext-ie8">
02  <divid=images-viewclass=" x-panel">   
03    <divclass=x-panel-tl>   
04         <divclass=x-panel-tr>   
05           <divclass=x-panel-tc>   
06             <divstyle="MozUserSelect: none; KhtmlUserSelect: none"id=ext-gen4class="x-panel-header x-unselectable"unselectable="on">   
07               <divid=ext-gen9class="x-tool x-tool-toggle"> </div>  
08                <spanclass=x-panel-header-text></span>  
09             </div>  
10           </div>  
11        </div>  
12   </div>   
13   <divid=ext-gen5class=x-panel-bwrap>   
14      <divclass=x-panel-ml>   
15        <divclass=x-panel-mr>   
16          <divid=ext-gen8class=x-panel-mc>   
17            <divid=ext-gen6class=x-panel-body></div>  
18          </div>  
19        </div>  
20      </div>   
21    <divid=ext-gen7class="x-panel-bl x-panel-nofooter">   
22        <divclass=x-panel-br>   
23          <divclass=x-panel-bc></div>  
24        </div>  
25      </div>  
26   </div>  
27  </div
28 </body>
view source print ?
<divid=ext-gen6class=x-panel-body></div> 可以看出x-panel-body中什么也没有,因此可以推测出当执行完this.afterRender(this.container)之后。将会将myData中的数据填充到其内部

 接下来分析Ext.Component中的render方法中的this.afterRender(this.container)方法。根据图(2)中的继承关系图可以知道 this.afterRender(this.container)会调用Panel中的afterRender方法。调用Panel中的afterRender方法,沿着继承链向上回溯,Ext.Componet和Ext.BoxComponent中的afterRender方法不是分析的重点,可自行查看源码。当执行到Ext.Container中的afterRender方法时

view source print ?
01 Ext.Container = Ext.extend(Ext.BoxComponent, {
02    
03     //...
04        
05      afterRender:function(){
06         
07         //...
08         if(!this.ownerCt){
09             this.doLayout(false,true);
10          }
11        //...
12      },
13      doLayout :function(shallow, force){
14          
15          //...
16         if(rendered &&this.layout){
17             this.layout.layout();
18         }
19         //...
20     }
21        
22    //... 
23 });

当执行到this.layout.layout()的时候,因为传入panel中的object literal 中layout:'fit'则布局为Ext.layout.FitLayout,而Ext.layout.FitLayout继承自Ext.layout.ContainerLayout 如图(2)所示。因此this.layout.Layout将会调用Ext.layout.ContainerLayout中的layout方法

view source print ?
01 Ext.layout.ContainerLayout = Ext.extend(Object, {
02  //...
03   
04    layout :function(){
05      //...
06      this.onLayout(ct, target);       
07      //...
08     },
09    onLayout :function(ct, target){
10         this.renderAll(ct, target);
11     },
12     renderAll :function(ct, target){
13         varitems = ct.items.items, i, c, len = items.length;
14         for(i = 0; i < len; i++) {
15             c = items[i];
16             if(c && (!c.rendered || !this.isValidParent(c, target))){
17                 this.renderItem(c, i, target);
18             }
19         }
20     },
21     renderItem :function(c, position, target){
22      if(c){
23          if(!c.rendered) {
24                 c.render(target, position);
25                 this.configureItem(c);
26           }
27          elseif(!this.isValidParent(c, target)){
28           //...
29           }
30       }
31       
32     }
33 //...
34 });

调用Ext.layout.ContainerLayout中的layout方法 最终我们将目光锁定在 c.render(target,positon)上,而c参数是由renderAll传入进来的,分析renderAll得知c的执行环境为最先实例化的items 故将调用Ext.DataView中的render方法,通过图(2)得知实质将调用Ext.Component的render方法,当执行Ext.Componet方法的时候,前面已经分析了。当调用this.afterRender,此时this指向Ext.DataView,将调用Ext.DataView的afterRender方法

view source print ?
01 Ext.DataView = Ext.extend(Ext.BoxComponent, {
02   
03  //...
04   
05   afterRender :function(){
06     //...
07    if(this.store){
08             this.bindStore(this.store,true);
09     },
10     bindStore :function(store, initial){
11      //...
12       if(store){
13             this.refresh();
14         }  
15      }
16   },
17    refresh :function() {
18     //...
19     this.tpl.overwrite(el,this.collectData(records, 0));
20    //...
21  }
22 //...
23 });

this.refresh()是关键之所在,EXTJS将在这个函数将myData填充到模板之中。到处为上已经全部分析完了,要理解这整个过程的前提是你必须对EXTJS有一定的了解,而不只是会简单使用,就像拖拉控件一样。如果这样的话,你会看的云里雾里,建议你还是不要看为好。


链接:http://www.cnblogs.com/yql1986/archive/2011/03/11/1981446.html 

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