C# File类常用方法
File 类
提供用于创建、复制、删除、移动和打开文件的静态方法，并协助创建 FileStream 对象。
1. File.Exists —— 确定指定的文件是否存在。
public static bool Exists(string path)
string curFile = @"c:\temp\test.txt";
Console.WriteLine(File.Exists(curFile) ? "File exists." : "File does not exist.");
2. File.AppendAllText 方法 —— 将指定的字符串追加到文件中，如果文件还不存在则创建该文件。
public static void AppendAllText(string path,string contents)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string createText = "Hello and Welcome" + Environment.NewLine;
File.WriteAllText(path, createText);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText); // Open the file to read from.
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}
void public static void AppendAllText(string path,string contents,Encoding encoding)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string createText = "Hello and Welcome" + Environment.NewLine;
File.WriteAllText(path, createText, Encoding.UTF8);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8); // Open the file to read from.
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}
3. File.ReadAllText 方法 —— 打开一个文本文件，将文件的所有行读入一个字符串，然后关闭该文件。
public static string ReadAllText(string path)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string createText = "Hello and Welcome" + Environment.NewLine;
File.WriteAllText(path, createText);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText); // Open the file to read from.
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}
public static string ReadAllText(string path,Encoding encoding)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string createText = "Hello and Welcome" + Environment.NewLine;
File.WriteAllText(path, createText, Encoding.UTF8);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8); // Open the file to read from.
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}
4. File.ReadAllLines 方法 —— 打开一个文本文件，将文件的所有行都读入一个字符串数组，然后关闭该文件。
public static string[] ReadAllLines(string path)
using System;
using System.IO;
class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string[] createText = { "Hello", "And", "Welcome" };
File.WriteAllLines(path, createText);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText); // Open the file to read from.
string[] readText = File.ReadAllLines(path);
foreach (string s in readText)
{
Console.WriteLine(s);
}
}
}
public static string[] ReadAllLines(string path,Encoding encoding)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string[] createText = { "Hello", "And", "Welcome" };
File.WriteAllLines(path, createText, Encoding.UTF8);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8); // Open the file to read from.
string[] readText = File.ReadAllLines(path, Encoding.UTF8);
foreach (string s in readText)
{
Console.WriteLine(s);
}
}
}
5. File.WriteAllText 方法 —— 创建一个新文件，在文件中写入内容，然后关闭文件。 如果目标文件已存在，则覆盖该文件。
public static void WriteAllText(string path,string contents)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string createText = "Hello and Welcome" + Environment.NewLine;
File.WriteAllText(path, createText);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText); // Open the file to read from.
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}
public static void WriteAllText(string path,string contents,Encoding encoding)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string createText = "Hello and Welcome" + Environment.NewLine;
File.WriteAllText(path, createText, Encoding.UTF8);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8); // Open the file to read from.
string readText = File.ReadAllText(path);
Console.WriteLine(readText);
}
}
6. File.WriteAllLines 方法 —— 创建一个新文件，在其中写入一个或多个字符串，然后关闭该文件。
public static void WriteAllLines(string path,string[] contents)
using System;
using System.IO;
class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string[] createText = { "Hello", "And", "Welcome" };
File.WriteAllLines(path, createText);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText); // Open the file to read from.
string[] readText = File.ReadAllLines(path);
foreach (string s in readText)
{
Console.WriteLine(s);
}
}
}
public static void WriteAllLines(string path,string[] contents,Encoding encoding)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; // This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string[] createText = { "Hello", "And", "Welcome" };
File.WriteAllLines(path, createText, Encoding.UTF8);
} // This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8); // Open the file to read from.
string[] readText = File.ReadAllLines(path, Encoding.UTF8);
foreach (string s in readText)
{
Console.WriteLine(s);
}
}
}
7.1. File.Create 方法 —— 在指定路径中创建或覆盖文件。
public static FileStream Create(string path)
using System;
using System.IO;
using System.Text; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt"; try
{ // Delete the file if it exists.
if (File.Exists(path))
{
// Note that no lock is put on the
// file and the possibility exists
// that another process could do
// something with it between
// the calls to Exists and Delete.
File.Delete(path);
} // Create the file.
using (FileStream fs = File.Create(path))
{
Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");
// Add some information to the file.
fs.Write(info, , info.Length);
} // Open the stream and read it back.
using (StreamReader sr = File.OpenText(path))
{
string s = "";
while ((s = sr.ReadLine()) != null)
{
Console.WriteLine(s);
}
}
} catch (Exception Ex)
{
Console.WriteLine(Ex.ToString());
}
}
}
7.2 File.Copy 方法 —— 将现有文件复制到新文件。
public static void Copy(string sourceFileName,string destFileName) 将现有文件复制到新文件。 不允许覆盖同名的文件。
string sourceDir = @"c:\current";
string backupDir = @"c:\archives\2008"; try
{
string[] picList = Directory.GetFiles(sourceDir, "*.jpg");
string[] txtList = Directory.GetFiles(sourceDir, "*.txt"); // Copy picture files.
foreach (string f in picList)
{
// Remove path from the file name.
string fName = f.Substring(sourceDir.Length + ); // Use the Path.Combine method to safely append the file name to the path.
// Will overwrite if the destination file already exists.
File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName), true);
} // Copy text files.
foreach (string f in txtList)
{ // Remove path from the file name.
string fName = f.Substring(sourceDir.Length + ); try
{
// Will not overwrite if the destination file already exists.
File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName));
} // Catch exception if the file was already copied.
catch (IOException copyError)
{
Console.WriteLine(copyError.Message);
}
} // Delete source files that were copied.
foreach (string f in txtList)
{
File.Delete(f);
}
foreach (string f in picList)
{
File.Delete(f);
}
} catch (DirectoryNotFoundException dirNotFound)
{
Console.WriteLine(dirNotFound.Message);
}
public static void Copy(string sourceFileName,string destFileName,bool overwrite)
string sourceDir = @"c:\current";
string backupDir = @"c:\archives\2008"; try
{
string[] picList = Directory.GetFiles(sourceDir, "*.jpg");
string[] txtList = Directory.GetFiles(sourceDir, "*.txt"); // Copy picture files.
foreach (string f in picList)
{
// Remove path from the file name.
string fName = f.Substring(sourceDir.Length + ); // Use the Path.Combine method to safely append the file name to the path.
// Will overwrite if the destination file already exists.
File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName), true);
} // Copy text files.
foreach (string f in txtList)
{ // Remove path from the file name.
string fName = f.Substring(sourceDir.Length + ); try
{
// Will not overwrite if the destination file already exists.
File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName));
} // Catch exception if the file was already copied.
catch (IOException copyError)
{
Console.WriteLine(copyError.Message);
}
} // Delete source files that were copied.
foreach (string f in txtList)
{
File.Delete(f);
}
foreach (string f in picList)
{
File.Delete(f);
}
} catch (DirectoryNotFoundException dirNotFound)
{
Console.WriteLine(dirNotFound.Message);
}
7.3 File.Move 方法 —— 将指定文件移到新位置，并提供指定新文件名的选项。
public static void Move(string sourceFileName,string destFileName)
using System;
using System.IO; class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt";
string path2 = @"c:\temp2\MyTest.txt";
try
{
if (!File.Exists(path))
{
// This statement ensures that the file is created,
// but the handle is not kept.
using (FileStream fs = File.Create(path)) {}
} // Ensure that the target does not exist.
if (File.Exists(path2))
File.Delete(path2); // Move the file.
File.Move(path, path2);
Console.WriteLine("{0} was moved to {1}.", path, path2); // See if the original exists now.
if (File.Exists(path))
{
Console.WriteLine("The original file still exists, which is unexpected.");
}
else
{
Console.WriteLine("The original file no longer exists, which is expected.");
} }
catch (Exception e)
{
Console.WriteLine("The process failed: {0}", e.ToString());
}
}
}
7.4 File.Delete 方法 ——删除指定的文件。
public static void Delete(string path)
string sourceDir = @"c:\current";
string backupDir = @"c:\archives\2008"; try
{
string[] picList = Directory.GetFiles(sourceDir, "*.jpg");
string[] txtList = Directory.GetFiles(sourceDir, "*.txt"); // Copy picture files.
foreach (string f in picList)
{
// Remove path from the file name.
string fName = f.Substring(sourceDir.Length + ); // Use the Path.Combine method to safely append the file name to the path.
// Will overwrite if the destination file already exists.
File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName), true);
} // Copy text files.
foreach (string f in txtList)
{ // Remove path from the file name.
string fName = f.Substring(sourceDir.Length + ); try
{
// Will not overwrite if the destination file already exists.
File.Copy(Path.Combine(sourceDir, fName), Path.Combine(backupDir, fName));
} // Catch exception if the file was already copied.
catch (IOException copyError)
{
Console.WriteLine(copyError.Message);
}
} // Delete source files that were copied.
foreach (string f in txtList)
{
File.Delete(f);
}
foreach (string f in picList)
{
File.Delete(f);
}
} catch (DirectoryNotFoundException dirNotFound)
{
Console.WriteLine(dirNotFound.Message);
}
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