桌面应用开发的日子(二):实现文件资源管理列表树加载

已矣乎！寓形宇内复几时？曷不委心任去留？胡为乎遑遑欲何之？富贵非吾愿，帝乡不可期。怀良辰以孤往，或植杖而耘耔。登东皋以舒啸，临清流而赋诗。聊乘化以归尽，乐夫天命复奚疑！————《归去来兮辞并序》·陶渊明

实现效果

获取本地逻辑驱动器、文件夹、文件

directory.getlogicaldrives();
directory.getdirectories(fullpath); // 返回指定目录中的子目录
directory.getfiles(fullpath); // 返回指定目录中的文件

// 截取文件或文件夹名称
public static string getfilefoldername(string path)
{
    if (string.isnullorempty(path))
        return string.empty;
    path = path.replace("/", "\\");

    var lastindex = path.lastindexof("\\");
    if (lastindex <= 0)
        return path;

    return path.substring(lastindex + 1);
}

通过mvvm模式，实现后台数据与ui进行绑定，下面是树ui结构定义和实体，视图模型的定义

<treeview x:name="foldertreeview" grid.row="1" itemssource="{binding items}">
    <treeview.itemcontainerstyle>
        <style targettype="{x:type treeviewitem}">
            <setter property="isexpanded" value="{binding isexpanded,mode=twoway}"/>
        </style>
    </treeview.itemcontainerstyle>
    <treeview.itemtemplate>
        <hierarchicaldatatemplate itemssource="{binding children}">
            <stackpanel orientation="horizontal">
                <textblock margin="3" fontfamily="{staticresource iconfont}" fontsize="26" foreground="{binding iconcolor}" text="{binding icon}" />
                <textblock  verticalalignment="center" fontsize="18" text="{binding name}"/>
            </stackpanel>
        </hierarchicaldatatemplate>
    </treeview.itemtemplate>
</treeview>

public class directoryitem
{
    public string fullpath { get; set; }
    public directoryitemtype type { get; set; }
    public string name
    {
        get
        {
            return this.type == directoryitemtype.drive ?
              this.fullpath :
              directorystructure.getfilefoldername(this.fullpath);
        }
    }
    public string icon { get; set; }
    public brush iconcolor { get; set; }
}

public class directoryitemviewmodel : baseviewmodel
{
    /// <summary>
    /// 全路径
    /// </summary>
    public string fullpath { get; set; }

    /// <summary>
    /// 成员类型
    /// </summary>
    public directoryitemtype type { get; set; }

    /// <summary>
    /// 成员名称
    /// </summary>
    public string name
    {
        get
        {
            return this.type == directoryitemtype.drive ?
              this.fullpath :
              directorystructure.getfilefoldername(this.fullpath);
        }
    }

    /// <summary>
    /// 成员图标
    /// </summary>
    public string icon { get; set; }

    /// <summary>
    /// 图标颜色
    /// </summary>
    public brush iconcolor { get; set; }

    /// <summary>
    /// 子成员
    /// </summary>
    public observablecollection<directoryitemviewmodel> children { get; set; }

    /// <summary>
    /// 表示成员是否可以展开
    /// </summary>
    public bool canexpend { get { return this.type != directoryitemtype.file; } }

    /// <summary>
    /// 展开/收缩的处理
    /// </summary>
    public bool isexpanded
    {
        get
        {
            return this.children?.count(x => x != null) > 0;
        }
        set
        {
            if (value)
                expand();
            else
                clearchildren();
        }
    }


    public icommand expandcommand { get; set; }

    public directoryitemviewmodel()
    {
        this.expandcommand = new relaycommand(expand);
        this.clearchildren();
    }

    private void clearchildren()
    {
        this.children = new observablecollection<directoryitemviewmodel>();
        if (this.type != directoryitemtype.file)
            this.children.add(null);
    }

    /// <summary>
    /// 展开目录并找到所有子成员
    /// </summary>
    private void expand()
    {
        if (this.type == directoryitemtype.file)
            return;
        var children = directorystructure.getdirectcontents(this.fullpath);
        var selector = children.select(x => new directoryitemviewmodel()
        {
            fullpath = x.fullpath,
            type = x.type,
            icon = x.icon,
            iconcolor = x.iconcolor
        });
        this.children = new observablecollection<directoryitemviewmodel>(selector);
    }
}
public class directorystructureviewmodel : baseviewmodel
{
    public observablecollection<directoryitemviewmodel> items { get; set; }

    public directorystructureviewmodel()
    {
        var children = directorystructure.getlogicaldrives();
        var selector = children.select(x =>
        new directoryitemviewmodel()
        {
            fullpath = x.fullpath,
            type = x.type,
            icon = x.icon,
            iconcolor = x.iconcolor
        });
        this.items = new observablecollection<directoryitemviewmodel>(selector);
    }
}

构建基类视图模型

[addinotifypropertychangedinterface]
public class baseviewmodel : inotifypropertychanged
{
    public event propertychangedeventhandler propertychanged=(sender, e)=>{}; //数据变化时通知前端
}

通过命令，点击逻辑器或文件夹时，加载子元素

    public class relaycommand : icommand
    {
        private action action;

        public event eventhandler canexecutechanged = (sender, e) => { };

        public relaycommand(action action)
        {
            this.action = action;
        }

        public bool canexecute(object parameter)
        {
            return true;
        }

        public void execute(object parameter)
        {
            action();
        }
    }

相关参考：
https://github.com/fody/propertychanged