ext 树的参考

http://chenjumin.iteye.com/blog/671752



/*!
* Ext JS Library 3.2.1
* Copyright(c) 2006-2010 Ext JS, Inc.
* licensing@extjs.com
* http://www.extjs.com/license
*/
Ext.onReady(function(){
    var tree = new Ext.ux.tree.ColumnTree({
        width: 850,
        height: 500,
enableDD:true,
        rootVisible:true,
        autoScroll:true,
        checkModel:'cascade',//级联多选，如果不需要checkbox,该属性去掉  
        onlyLeafCheckable: false,//所有结点可选，如果不需要checkbox,该属性去掉
        title: 'Example Tasks',
        renderTo: Ext.getBody(),

  listeners: {
            'checkchange': function(node, checked){
                if(checked){
                    node.getUI().addClass('complete');
                }else{
                    node.getUI().removeClass('complete');
                }
            }
        },
       
        buttons: [{
            text: 'Get Completed Tasks',
            handler: function(){
                var msg = '', selNodes = tree.getSelectionModel().getSelectedNode();
selNodes = tree.getChecked();
              
                Ext.each(selNodes, function(node){
                    if(msg.length > 0){
                        msg += ', ';
                    }
                    msg += node.attributes.id;

//alert(msg);
                });
                Ext.Msg.show({
                    title: 'Completed Tasks',
                    msg: msg.length > 0 ? msg : 'None',
                    icon: Ext.Msg.INFO,
                    minWidth: 200,
                    buttons: Ext.Msg.OK
                });
            }
        }],
 






        columns:[{
            header:'Task',
            width:330,
            dataIndex:'task'
        },{
            header:'Duration',
            width:200,
            dataIndex:'duration'
        },{
            header:'Assigned To',
            width:300,
            dataIndex:'user'
        }],

        loader: new Ext.tree.TreeLoader({
           // dataUrl:'column-data.json',
            uiProviders:{
                'col':Ext.ux.ColumnTreeCheckNodeUI
            }
        }),

        root: new Ext.tree.AsyncTreeNode({
            text:'Tasks'
        })
    });


tree.on('beforeload',
                function(node){
                  // tree.loader.dataUrl='column-data.json';
   alert("123");//定义子节点的Loader   
                });
});