下载从邮件请求返回的文件的Extjs 4(下面的代码为3.4)

Ext.define('MyApp.view.MyGrid', {
    extend: 'Ext.grid.Panel',
    alias: 'widget.mygrid',

    title: 'My Email Grid',
    store: 'MyEmailStore',

    columns: [
        { header: 'From', dataIndex: 'from', flex: 1 },
        { header: 'Subject', dataIndex: 'subject', flex: 1 },
        { header: 'Date', dataIndex: 'date', flex: 1 }
    ],

    dockedItems: [
        {
            xtype: 'toolbar',
            dock: 'top',
            items: [
                {
                    xtype: 'button',
                    text: 'Download Attachment',
                    handler: function() {
                        var selected = this.up('grid').getSelectionModel().getSelection();
                        if (selected.length > 0) {
                            var email = selected[0];
                            // Code to download the attachment goes here
                        }
                    }
                }
            ]
        }
    ]
});