根据后台json生成左侧导航菜单

文章内不再提供示例，需要查看者请从SVN下载，地址：
http://exttools.googlecode.com/svn/trunk/
效果图：

/**
 * 扩展了Panel类，其布局设为accordion，所在区域为west；该组件初始化后会根据配置的url和root向后台发
 * 起请求并解析返回的json串，根据parentcode为空的结点生成TreePanel，子节点通过parentcode属性添加为
 * 对应结点的子节点，注意此处每个节点的code必须小于父节点并接大于下方的其它结点;
 *
 * 1.1更新：
 * 1.不再需要leaf属性，程序内部判断；
 * 2.store用完后即销毁，不再可用；
 * 3.修改了结点点击的触发事件，仅注册一次以减少内存占用，该方法传递给监听函数一个Ext.tree.TreeNode对象，
 * 可通过node.attributes属性获取结点属性；
 * 4.添加了一个findNodeById方法，该方法通过id字符串返回对应Ext.tree.TreeNode对象；
 *
 * @author [e-mail]
 * @version 1.1
 * @since 2010-5-9
 *
 */
Ext.namespace("QM.ui");

QM.ui.AccordinTreePanel = Ext.extend(Ext.Panel, {
    /**
     * @cfg(url) 发送请求的地址
     */
    /**
     * @cfg(root) json数组的根字符串
     */
    margins: '5 0 5 5',
    split: true,
    width: 210,
    initComponent: function(){
        Ext.apply(this, {
            layout: 'accordion',
            region: 'west'
        })
        QM.ui.AccordinTreePanel.superclass.initComponent.call(this);
        this.addEvents(        /**
         * @event itemclick  树结点被点击时触发  参数：node 当前结点对象，record 当前结点对应record对象
         */
        'click',        /**
         * @event afterload 菜单项加载完毕后触发
         */
        'afterload');
        if (!this.store) {
            this.store = new Ext.data.JsonStore({
                url: this.url,
                root: this.root,
                fields: ['code', 'name', 'parentcode', 'iconCls', 'href']
            });
        }
        this.store.load({
            callback: this.loadTrees,
            scope: this
        });
    },
    loadTrees: function(records, o, s){
        var pnodes,trees = [],tree;
        this.store.sort('code');
        for (var i = 0; i < records.length; i++) {
            var record = records[i];
            if (!record.get('parentcode')) {
                tree = this.creatTreeConfig(record);
                trees.push(tree);
                pnodes = [];
                pnodes.push(tree.root);
            }
            else {
                var next_record = records[i + 1];
                var isLeaf = !next_record || next_record.get('parentcode') != record.get('code');
                this.addTreeNode(pnodes, record, isLeaf);
            }
        }
        Ext.each(trees,function(tree){
            this.add(tree);
        },this);
        this.fireEvent('afterload', this);
        this.mon(this.el, 'click', this.onClick, this);
        this.doLayout();
        this.store.destroy();
    },
    findNodeById:function(id){
        var node,trees = this.findByType('treepanel',true);
        Ext.each(trees,function(tree){
            node = tree.getNodeById(id);
            return !node;//找到的话返回false
        });
        return node;
    },
    onClick: function(e, t, o){
        if(Ext.fly(t).hasClass('x-tree-ec-icon')){//点击伸展按钮时无视
            return;
        }
        var el,id,node;
        if (el = e.getTarget('.x-tree-node-el', 3,true)) {
            e.stopEvent();
            id = el.getAttributeNS('ext','tree-node-id');
            node = this.findNodeById(id);
            this.fireEvent('click',node);
        }
    },
    creatTreeConfig: function(record){
        var config = {
            xtype: 'treepanel',
            autoScroll: true,
            rootVisible: false,
            title: record.get('name'),
            iconCls: record.get('iconCls'),
            root: {
                nodeType: 'async',
                expanded: true,
                id: record.get('code'),
                children: []
            }
        };
        return config;
    },
    addTreeNode: function(pnodes, record, isLeaf){
        var len = pnodes.length;
        for (var i = len - 1; i >= 0; i--) {
            if (pnodes[i].id != record.get('parentcode')) {
                pnodes.pop();
            }
            else {
                var parent = pnodes[i].children;
                var node = {
                    text: record.get('name'),
                    id: record.get('code'),
                    iconCls: record.get('iconCls'),
                    href: record.get('href'),
                    leaf: isLeaf
                };
                if (!isLeaf) {
                    node.children = [];
                    pnodes.push(node);
                }
                parent.push(node);
                return;
            }
        }
    }
});

Ext.reg('accTree', QM.ui.AccordinTreePanel);

/**
 * 扩展了Panel类，其布局设为accordion，所在区域为west；该组件初始化后会根据配置的url和root向后台发
 * 起请求并解析返回的json串，根据parentcode为空的结点生成TreePanel，子节点通过parentcode属性添加为
 * 对应结点的子节点，注意此处每个节点的code必须小于父节点并接大于下方的其它结点;
 * 
 * 1.1更新：
 * 1.不再需要leaf属性，程序内部判断；
 * 2.store用完后即销毁，不再可用；
 * 3.修改了结点点击的触发事件，仅注册一次以减少内存占用，该方法传递给监听函数一个Ext.tree.TreeNode对象，
 * 可通过node.attributes属性获取结点属性；
 * 4.添加了一个findNodeById方法，该方法通过id字符串返回对应Ext.tree.TreeNode对象；
 * 
 * @author [e-mail]
 * @version 1.1
 * @since 2010-5-9
 *
 */
Ext.namespace("QM.ui");

QM.ui.AccordinTreePanel = Ext.extend(Ext.Panel, {
    /**
     * @cfg(url) 发送请求的地址
     */
    /**
     * @cfg(root) json数组的根字符串
     */
    margins: '5 0 5 5',
    split: true,
    width: 210,
    initComponent: function(){
        Ext.apply(this, {
            layout: 'accordion',
            region: 'west'
        })
        QM.ui.AccordinTreePanel.superclass.initComponent.call(this);
        this.addEvents(        /**
         * @event itemclick  树结点被点击时触发  参数：node 当前结点对象，record 当前结点对应record对象
         */
        'click',        /**
         * @event afterload 菜单项加载完毕后触发
         */
        'afterload');
        if (!this.store) {
            this.store = new Ext.data.JsonStore({
                url: this.url,
                root: this.root,
                fields: ['code', 'name', 'parentcode', 'iconCls', 'href']
            });
        }
        this.store.load({
            callback: this.loadTrees,
            scope: this
        });
    },
    loadTrees: function(records, o, s){
        var pnodes,trees = [],tree;
        this.store.sort('code');
        for (var i = 0; i < records.length; i++) {
            var record = records[i];
            if (!record.get('parentcode')) {
                tree = this.creatTreeConfig(record);
				trees.push(tree);
                pnodes = [];
                pnodes.push(tree.root);
            }
            else {
                var next_record = records[i + 1];
                var isLeaf = !next_record || next_record.get('parentcode') != record.get('code');
                this.addTreeNode(pnodes, record, isLeaf);
            }
        }
		Ext.each(trees,function(tree){
			this.add(tree);
		},this);
        this.fireEvent('afterload', this);
        this.mon(this.el, 'click', this.onClick, this);
        this.doLayout();
        this.store.destroy();
    },
	findNodeById:function(id){
		var node,trees = this.findByType('treepanel',true);
		Ext.each(trees,function(tree){
			node = tree.getNodeById(id);
			return !node;//找到的话返回false
		});
		return node;
	},
    onClick: function(e, t, o){
		if(Ext.fly(t).hasClass('x-tree-ec-icon')){//点击伸展按钮时无视
			return;
		}
		var el,id,node;   
		if (el = e.getTarget('.x-tree-node-el', 3,true)) {
			e.stopEvent();
			id = el.getAttributeNS('ext','tree-node-id');
			node = this.findNodeById(id);
			this.fireEvent('click',node);
		}
    },
    creatTreeConfig: function(record){
        var config = {
            xtype: 'treepanel',
            autoScroll: true,
            rootVisible: false,
            title: record.get('name'),
            iconCls: record.get('iconCls'),
            root: {
                nodeType: 'async',
                expanded: true,
                id: record.get('code'),
                children: []
            }
        };
        return config;
    },
    addTreeNode: function(pnodes, record, isLeaf){
        var len = pnodes.length;
        for (var i = len - 1; i >= 0; i--) {
            if (pnodes[i].id != record.get('parentcode')) {
                pnodes.pop();
            }
            else {
                var parent = pnodes[i].children;
                var node = {
                    text: record.get('name'),
                    id: record.get('code'),
                    iconCls: record.get('iconCls'),
                    href: record.get('href'),
                    leaf: isLeaf
                };
                if (!isLeaf) {
                    node.children = [];
                    pnodes.push(node);
                }
                parent.push(node);
                return;
            }
        }
    }
});

Ext.reg('accTree', QM.ui.AccordinTreePanel);

示例js：

new Ext.Viewport({
                    layout: 'border',
                    items: [{
                        xtype: 'accTree',
                        title : '菜单',
                        root : 'menus',//必须要配
                        url: 'menu.json',//必须要配
                        listeners:{
                            'click':function(node){
                                alert(node.attributes.href);
                            }
                        }
                    }, {
                        region: 'center',
                        html: 'center'
                    }]
                });
            });