c# 扩展方法奇思妙用变态篇四:string 的翻身革命
2009-08-26 20:27 鹤冲天 阅读(8663) 评论(61) 编辑 收藏 举报string是各种编程语言中最基础的数据类型,长期以来受尽其它类的压迫,经常被肢解(Substring、Split)、蹂躏(Join)...
而现在string要“翻身闹革命”了,它几乎无所不能,可以为所欲为,令其它类心惊胆颤...
让我们来看一下革命后的string做了些什么?
打开文件或网址
1 "c:\\t.txt".Open();
2 "http://www.cnblogs.com/ldp615/".Open();
2 "http://www.cnblogs.com/ldp615/".Open();
怎么做到的呢?看扩展,很简单,直接调用调用了Process.Start函数:
1 public static void Open(this string s)
2 {
3 Process.Start(s);
4 }
2 {
3 Process.Start(s);
4 }
单单打开个文件,窃取他人信息只是初步操作,string还可以修改、删除、创建文件(或目录)
文件及目录操作
1 @"C:\Directory".CreateDirectory();
2 @"C:\Directory\readme.txt".WriteText("this file is created by string!");
3 @"C:\abc.txt".DeleteFile();
2 @"C:\Directory\readme.txt".WriteText("this file is created by string!");
3 @"C:\abc.txt".DeleteFile();
实现同样简单,调用File及Directory类。以下上面三个扩展的实现。(当然还可以实现更多文件及目录操作,很简单,不再给出!)
1 public static void CreateDirectory(this string path)
2 {
3 Directory.CreateDirectory(path);
4 }
5 public static void WriteText(this string path, string contents)
6 {
7 File.WriteAllText(path, contents);
8 }
9 public static void DeleteFile(this string path)
10 {
11 if(File.Exists(path)) File.Delete(path);
12 }
2 {
3 Directory.CreateDirectory(path);
4 }
5 public static void WriteText(this string path, string contents)
6 {
7 File.WriteAllText(path, contents);
8 }
9 public static void DeleteFile(this string path)
10 {
11 if(File.Exists(path)) File.Delete(path);
12 }
还是感觉不过瘾,想要删除整个硬盘的文件,用上面的一个一个来也太麻烦了。也没问题,看下面:
执行DOS命令
先看两个简单的
1 string output1 = "del c:\\t1.txt".ExecuteDOS();
2 string output2 = "dir".ExecuteDOS();
2 string output2 = "dir".ExecuteDOS();
实现也用了Process类,如下:
1 public static string ExecuteDOS(this string cmd)
2 {
3 Process process = new Process();
4 process.StartInfo.FileName = "cmd.exe";
5 process.StartInfo.UseShellExecute = false;
6 process.StartInfo.RedirectStandardInput = true;
7 process.StartInfo.RedirectStandardOutput = true;
8 process.StartInfo.RedirectStandardError = true;
9 process.StartInfo.CreateNoWindow = true;
10 process.Start();
11 process.StandardInput.WriteLine(cmd);
12 process.StandardInput.WriteLine("exit");
13 return process.StandardOutput.ReadToEnd();
14 }
2 {
3 Process process = new Process();
4 process.StartInfo.FileName = "cmd.exe";
5 process.StartInfo.UseShellExecute = false;
6 process.StartInfo.RedirectStandardInput = true;
7 process.StartInfo.RedirectStandardOutput = true;
8 process.StartInfo.RedirectStandardError = true;
9 process.StartInfo.CreateNoWindow = true;
10 process.Start();
11 process.StandardInput.WriteLine(cmd);
12 process.StandardInput.WriteLine("exit");
13 return process.StandardOutput.ReadToEnd();
14 }
DOS命令也会有异常发生,下面的实现可通过out参数返回错误信息:
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
有了这个扩展,格式化硬盘、关机、重启都不在话下!
1 "format c:".ExecuteDOS();
2 "shutdown -s".ExecuteDOS();
3 "shutdown -r".ExecuteDOS();
2 "shutdown -s".ExecuteDOS();
3 "shutdown -r".ExecuteDOS();
以上对付一般用户的电脑足够了,可但对程序员的电脑,他们居然把信息放进了数据库!同样有办法!
执行SQL
1 DbConnection conn = ![](https://www.cnblogs.com/Images/dot.gif)
2 int count = "select count(*) from Girlfriends".ExecuteScalar(conn).Cast<int>();
![](https://www.cnblogs.com/Images/dot.gif)
2 int count = "select count(*) from Girlfriends".ExecuteScalar(conn).Cast<int>();
参考实现如下:
1 public static object ExecuteScalar(this string sql, DbConnection conn)
2 {
3 object result;
4 using (DbCommand cmd = conn.CreateCommand())
5 {
6 cmd.Connection = conn;
7 cmd.CommandText = sql;
8 cmd.CommandType = System.Data.CommandType.Text;
9 conn.Open();
10 result = cmd.ExecuteScalar();
11 conn.Close();
12 }
13 return result;
14 }
2 {
3 object result;
4 using (DbCommand cmd = conn.CreateCommand())
5 {
6 cmd.Connection = conn;
7 cmd.CommandText = sql;
8 cmd.CommandType = System.Data.CommandType.Text;
9 conn.Open();
10 result = cmd.ExecuteScalar();
11 conn.Close();
12 }
13 return result;
14 }
还有Cast扩展:
1 public static T Cast<T>(this object obj)
2 {
3 return (T)obj;
4 }
2 {
3 return (T)obj;
4 }
现在可以执行了。结果是*** 同样还可以实现更多数据库操作。
总结
string还可以做更多更多事情,只要你支持它!但不要给它太多太大的权力,万一哪天比你强大了...
(改)变(形)态篇 文章,仅供开拓思路,实际项目慎用!
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