C#递归搜索指定目录下的文件或目录

https://www.cnblogs.com/huhangfei/p/5012978.html

诚然可以使用现成的Directory类下的GetFiles、GetDirectories、GetFileSystemEntries这几个方法实现同样的功能，但请相信我不是蛋疼，原因是这几个方法在遇上【System Volume Information】这种目录时，极有可能会给你个拒绝访问的异常，想跳过都不行。所以没办法，重新实现了一下。

实现说明

仍然是基于对Directory类的几个方法的封装进行实现，只是没有使用它们的searchPattern和searchOption功能
将匹配模式由windows的通配符?、改为正则匹配。一是让匹配更强大，二是要实现?匹配还得做额外工作，没必要

匹配模式并没有默认添加首尾限定$，即“abc"将会匹配所有包含该字串的项目，所以如果你要匹配首尾，请自行添加$

忽略大小写匹配

如果不想搜索指定项目而是全部，请将regexPattern参数设为null，而不是.*，前者性能更好
可通过设置recurse和throwEx参数决定是否递归搜索，和是否抛异常。默认是不递归，不抛异常
遇到不可访问的目录会跳过。当然前提是throwEx=false
之所以在foreach外层再套一层try-catch，是因为如果指定的dir就是不可访问的目录，那也可以避免异常
之所以为获取项、获取文件、获取目录分别实现3个方法，而不是只实现一个获取项，另外两个重载，是因为只实现一个的话，foreach中要做的逻辑判断不少，考虑到方法是要递归的，所以循环中逻辑越少越好
之所以不做dir参数合法性检查，原因同上，判断越少越好。所以请用户调用前自行确保dir合法

不废话，上代码：

/// <summary>
/// 获取指定目录中的匹配项（文件或目录）
/// </summary>
/// <param name="dir">要搜索的目录</param>
/// <param name="regexPattern">项名模式（正则）。null表示忽略模式匹配，返回所有项</param>
/// <param name="recurse">是否搜索子目录</param>
/// <param name="throwEx">是否抛异常</param>
/// <returns></returns>
private static string[] GetFileSystemEntries(string dir, string regexPattern = null, bool recurse = false, bool throwEx = false)
{
    List<string> lst = new List<string>();
</span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">
{
    </span><span style="color: rgba(0, 0, 255, 1)">foreach</span> (<span style="color: rgba(0, 0, 255, 1)">string</span> item <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> Directory.GetFileSystemEntries(dir))
    {
        </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">
        {
            </span><span style="color: rgba(0, 0, 255, 1)">if</span> (regexPattern == <span style="color: rgba(0, 0, 255, 1)">null</span> || Regex.IsMatch(Path.GetFileName(item), regexPattern, RegexOptions.IgnoreCase |<span style="color: rgba(0, 0, 0, 1)"> RegexOptions.Multiline))
            { lst.Add(item); }

            </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">递归</span>
            <span style="color: rgba(0, 0, 255, 1)">if</span> (recurse &amp;&amp; (File.GetAttributes(item) &amp; FileAttributes.Directory) ==<span style="color: rgba(0, 0, 0, 1)"> FileAttributes.Directory)
            { lst.AddRange(GetFileSystemEntries(item, regexPattern, </span><span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">)); }
        }
        </span><span style="color: rgba(0, 0, 255, 1)">catch</span> { <span style="color: rgba(0, 0, 255, 1)">if</span> (throwEx) { <span style="color: rgba(0, 0, 255, 1)">throw</span><span style="color: rgba(0, 0, 0, 1)">; } }
    }
}
</span><span style="color: rgba(0, 0, 255, 1)">catch</span> { <span style="color: rgba(0, 0, 255, 1)">if</span> (throwEx) { <span style="color: rgba(0, 0, 255, 1)">throw</span><span style="color: rgba(0, 0, 0, 1)">; } }

</span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> lst.ToArray();

}
/// <summary>

/// 获取指定目录中的匹配文件

/// </summary>

/// <param name="dir">要搜索的目录</param>

/// <param name="regexPattern">文件名模式（正则）。null表示忽略模式匹配，返回所有文件</param>

/// <param name="recurse">是否搜索子目录</param>

/// <param name="throwEx">是否抛异常</param>

/// <returns></returns>

private static string[] GetFiles(string dir, string regexPattern = null, bool recurse = false, bool throwEx = false)

{

List<string> lst = new List<string>();
</span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">
{
    </span><span style="color: rgba(0, 0, 255, 1)">foreach</span> (<span style="color: rgba(0, 0, 255, 1)">string</span> item <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> Directory.GetFileSystemEntries(dir))
    {
        </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">
        {
            </span><span style="color: rgba(0, 0, 255, 1)">bool</span> isFile = (File.GetAttributes(item) &amp; FileAttributes.Directory) !=<span style="color: rgba(0, 0, 0, 1)"> FileAttributes.Directory;

            </span><span style="color: rgba(0, 0, 255, 1)">if</span> (isFile &amp;&amp; (regexPattern == <span style="color: rgba(0, 0, 255, 1)">null</span> || Regex.IsMatch(Path.GetFileName(item), regexPattern, RegexOptions.IgnoreCase |<span style="color: rgba(0, 0, 0, 1)"> RegexOptions.Multiline)))
            { lst.Add(item); }

            </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">递归</span>
            <span style="color: rgba(0, 0, 255, 1)">if</span> (recurse &amp;&amp; !isFile) { lst.AddRange(GetFiles(item, regexPattern, <span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">)); }
        }
        </span><span style="color: rgba(0, 0, 255, 1)">catch</span> { <span style="color: rgba(0, 0, 255, 1)">if</span> (throwEx) { <span style="color: rgba(0, 0, 255, 1)">throw</span><span style="color: rgba(0, 0, 0, 1)">; } }
    }
}
</span><span style="color: rgba(0, 0, 255, 1)">catch</span> { <span style="color: rgba(0, 0, 255, 1)">if</span> (throwEx) { <span style="color: rgba(0, 0, 255, 1)">throw</span><span style="color: rgba(0, 0, 0, 1)">; } }

</span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> lst.ToArray();

}
/// <summary>

/// 获取指定目录中的匹配目录

/// </summary>

/// <param name="dir">要搜索的目录</param>

/// <param name="regexPattern">目录名模式（正则）。null表示忽略模式匹配，返回所有目录</param>

/// <param name="recurse">是否搜索子目录</param>

/// <param name="throwEx">是否抛异常</param>

/// <returns></returns>

private static string[] GetDirectories(string dir, string regexPattern = null, bool recurse = false, bool throwEx = false)

{

List<string> lst = new List<string>();
</span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">
{
    </span><span style="color: rgba(0, 0, 255, 1)">foreach</span> (<span style="color: rgba(0, 0, 255, 1)">string</span> item <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> Directory.GetDirectories(dir))
    {
        </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">
        {
            </span><span style="color: rgba(0, 0, 255, 1)">if</span> (regexPattern == <span style="color: rgba(0, 0, 255, 1)">null</span> || Regex.IsMatch(Path.GetFileName(item), regexPattern, RegexOptions.IgnoreCase |<span style="color: rgba(0, 0, 0, 1)"> RegexOptions.Multiline))
            { lst.Add(item); }

            </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">递归</span>
            <span style="color: rgba(0, 0, 255, 1)">if</span> (recurse) { lst.AddRange(GetDirectories(item, regexPattern, <span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">)); }
        }
        </span><span style="color: rgba(0, 0, 255, 1)">catch</span> { <span style="color: rgba(0, 0, 255, 1)">if</span> (throwEx) { <span style="color: rgba(0, 0, 255, 1)">throw</span><span style="color: rgba(0, 0, 0, 1)">; } }
    }
}
</span><span style="color: rgba(0, 0, 255, 1)">catch</span> { <span style="color: rgba(0, 0, 255, 1)">if</span> (throwEx) { <span style="color: rgba(0, 0, 255, 1)">throw</span><span style="color: rgba(0, 0, 0, 1)">; } }

</span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> lst.ToArray();

}