文件进程问题

Question

我今天编程出现了一个问题。他说  文件“C:\check.txt”正由另一进程使用，因此该进程无法访问该文件，请大家指点指点,帮我修正下。  
模块一：  private  void  checkBox1_CheckedChanged(object  sender,  EventArgs  e)  
               {  
                       if  (checkBox1.Checked  ==  true)  
                       {  
                               StreamWriter  ws;  
                               ws  =  File.CreateText("C:\\check.txt");  
                               ws.WriteLine("1");  
                               ws.Close();  
                       }  
                       else  
                       {  
                               StreamWriter  ws;  
                               ws  =  File.CreateText("C:\\check.txt");  
                               ws.WriteLine("0");  
                               ws.Close();  
                       }  
 
 
               }        
模块2：  private  void  Form1_Load(object  sender,  EventArgs  e)  
               {  
                       if  (File.Exists(@"C:\check.txt")  ==  true)  
                     
                     {  
                               StreamReader  rs  =  new  System.IO.StreamReader(@"C:\check.txt",  System.Text.Encoding.UTF8);  
                               string  s  =  rs.ReadLine();  
                               if  (s.Trim()  ==  "0")  
                               {  
                                       textBox2.Text  =  "";  
                                       textBox3.Text  =  "";  
                               }  
                               else  
                               {  
                                       checkBox1.Checked  =  true;  
                               }  
             rs.close();  
         }  
}

Answer 1

创建一个自定义CMutex进行同步

Answer 2

模块一：  Mutex m = new Mutex(false, "MyMutex");
private  void  checkBox1_CheckedChanged(object  sender,  EventArgs  e)  
               {  
                      m.WaitOne();
 if  (checkBox1.Checked  ==  true)  
                       {  
                               StreamWriter  ws;  
                               ws  =  File.CreateText("C:\\check.txt");  
                               ws.WriteLine("1");  
                               ws.Close();  
                       }  
                       else  
                       {  
                               StreamWriter  ws;  
                               ws  =  File.CreateText("C:\\check.txt");  
                               ws.WriteLine("0");  
                               ws.Close();  
                       }  
 m.ReleaseMutex(); 
               }        
模块2： Mutex m = new Mutex(false, "MyMutex");
 private  void  Form1_Load(object  sender,  EventArgs  e)  
               {  
               m.WaitOne();
        if  (File.Exists(@"C:\check.txt")  ==  true)  
                     
                     {  
                               StreamReader  rs  =  new  System.IO.StreamReader(@"C:\check.txt",  System.Text.Encoding.UTF8);  
                               string  s  =  rs.ReadLine();  
                               if  (s.Trim()  ==  "0")  
                               {  
                                       textBox2.Text  =  "";  
                                       textBox3.Text  =  "";  
                               }  
                               else  
                               {  
                                       checkBox1.Checked  =  true;  
                               }  
             rs.close();  
         }  
m.ReleaseMutex();}

Answer 3

问题在rs.Close之前又触发了CheckedChanged事件,在CheckedChanged事件中又会再次建立这个文件,所以会报错,下面是修改之后的代码
 private  void  Form1_Load(object  sender,  EventArgs  e)  
               {  
                       if  (File.Exists(@"C:\check.txt")  ==  true)  
                     
                     {  
                               StreamReader  rs  =  new  System.IO.StreamReader(@"C:\check.txt",  System.Text.Encoding.UTF8);  
                               string  s  =  rs.ReadLine();  
                               rs.close();  
                               if  (s.Trim()  ==  "0")  
                               {  
                                       textBox2.Text  =  "";  
                                       textBox3.Text  =  "";  
                               }  
                               else  
                               {  
                                       checkBox1.Checked  =  true;  
                               }           
         }  
}

Answer 4

只要在操作文件的地方都加上mutex锁就没问题了。不过要小心死锁。