前言
在winform中读取文件信息时，突然抛出了FileNotFoundException的异常，但是本地是有这个文件的。
随后找到了这个文件，查看属性，[位置]属性，多了"\\?\"的前缀，百度得知这是windows对长路经的处理。
需要注意：
目前在NetFx框架下，才有这个问题。
在NetCore框架下，是正常运行。
复现问题的代码
代码如下
static void Test02(){List<string> dirList = new List<string>(){"F:\\100-cnblogs_blog","01-all-备份备份备份备份备份备份备份","02-html-备份备份备份备份备份备份备份","03-bak-备份备份备份备份备份备份备份","04-file-备份备份备份备份备份备份备份",};string basePath = Path.Combine(dirList.ToArray());if (Directory.Exists(basePath) == false)Directory.CreateDirectory(basePath);//假设有这2个文件//这个文件是正常=>1.txt//这个文件会报错=>6bRLpUwRTXshio75MZtzxmqjtfRlIMXDKFPdAG1f63gdXvxoY5pPPUaermZuHsUfrLI90xSYW8qiYzucUV4GceuHqvpFVaojMkFS5g9mmE5QL5K2YEOkLWFuF2Oboi1JsbCEhMoD77SGczO7GgZX60XPQZuo7hZFP3LKqJ4EHYKL8yjdVAYAwpm737JikdH3OUQ9zOhh.txtvar files = Directory.GetFiles(basePath, "*.*", SearchOption.AllDirectories);foreach (var item in files){string fullName = item;FileInfo fileInfo = new FileInfo(fullName);Console.WriteLine(fileInfo.Name);string pre = " =>";bool retry = false;try{Console.WriteLine(pre + "Length：" + fileInfo.Length);Console.WriteLine(pre + "未报错，正常获取");}catch (FileNotFoundException){fullName = @"\\?\" + fullName;retry = true;Console.WriteLine(pre + "文件不存在，添加长路经前缀后重试");}if (retry){fileInfo = new FileInfo(fullName);try{Console.WriteLine(pre + "Length：" + fileInfo.Length);Console.WriteLine(pre + "重试后，正常获取");}catch (Exception ex){Console.WriteLine(pre + "重试仍然报错");Console.WriteLine(ex.Message);}}}}
运行结果
解决办法
先是考虑了捕获异常再重试的思路，但是在可预知的情况不应该使用trycatch方式处理问题。
所以采用了判断文件是否存在的方式
代码如下
static void Test03(){List<string> dirList = new List<string>(){"F:\\100-cnblogs_blog","01-all-备份备份备份备份备份备份备份","02-html-备份备份备份备份备份备份备份","03-bak-备份备份备份备份备份备份备份","04-file-备份备份备份备份备份备份备份",};string basePath = Path.Combine(dirList.ToArray());if (Directory.Exists(basePath) == false)Directory.CreateDirectory(basePath);var files = Directory.GetFiles(basePath, "*.*", SearchOption.AllDirectories);foreach (var item in files){string fullName = item;if (File.Exists(fullName) == false)fullName = @"\\?\" + fullName;FileInfo fileInfo = new FileInfo(fullName);Console.WriteLine(fileInfo.Name);string pre = " =>";Console.WriteLine(pre + "Length：" + fileInfo.Length);}}
运行结果
