File.Copy 方法

定义

命名空间:

System.IO

程序集:

System.Runtime.dll

将现有文件复制到新文件。

重载

Copy(String, String)	将现有文件复制到新文件。 不允许覆盖同名文件。
Copy(String, String, Boolean)	将现有文件复制到新文件。 允许覆盖同名文件。

Copy(String, String)

Source:

File.cs

将现有文件复制到新文件。 不允许覆盖同名文件。

public:
 static void Copy(System::String ^ sourceFileName, System::String ^ destFileName);

public static void Copy (string sourceFileName, string destFileName);

static member Copy : string * string -> unit

Public Shared Sub Copy (sourceFileName As String, destFileName As String)

参数

sourceFileName

String

要复制的文件。

destFileName

String

目标文件的名称。 这不能是目录或现有文件。

例外

UnauthorizedAccessException

调用方没有所需的权限。

ArgumentException

sourceFileName 或 destFileName 是长度为零的字符串，仅包含空格，或包含一个或多个无效字符。 可以使用 GetInvalidPathChars() 方法查询无效字符。

-或-

sourceFileName 或 destFileName 指定目录。

ArgumentNullException

sourceFileName 或 destFileNamenull。

PathTooLongException

指定的路径、文件名或两者都超过了系统定义的最大长度。

DirectoryNotFoundException

在 sourceFileName 或 destFileName 中指定的路径无效（例如，它位于未映射的驱动器上）。

FileNotFoundException

找不到 sourceFileName。

IOException

destFileName 存在。

-或-

发生 I/O 错误。

NotSupportedException

sourceFileName 或 destFileName 格式无效。

示例

以下示例将文件复制到 C：\archives\2008 备份文件夹。 它使用 Copy 方法的两个重载，如下所示：

• 它首先使用 File.Copy(String, String) 方法重载复制文本（.txt）文件。 该代码演示此重载不允许覆盖已复制的文件。

• 然后，它使用 File.Copy(String, String, Boolean) 方法重载复制图片（.jpg 文件）。 该代码演示此重载确实允许覆盖已复制的文件。

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 + 1);

        // 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 + 1);

        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);
}

let sourceDir = @"c:\current"
let backupDir = @"c:\archives\2008"

try
    let picList = Directory.GetFiles(sourceDir, "*.jpg")
    let txtList = Directory.GetFiles(sourceDir, "*.txt")

    // Copy picture files.
    for f in picList do
        // Remove path from the file name.
        let fName = f.Substring(sourceDir.Length + 1)

        // 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.
    for f in txtList do
        // Remove path from the file name.
        let fName = f.Substring(sourceDir.Length + 1)

        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.
        with
        | :? IOException as copyError -> printfn $"{copyError.Message}"

    // Delete source files that were copied.
    for f in txtList do
        File.Delete f

    for f in picList do
        File.Delete f

// Catch exception if the file was already copied.
with
| :? DirectoryNotFoundException as dirNotFound -> printfn $"{dirNotFound.Message}"

Dim sourceDir As String = "c:\current"
Dim backupDir As String = "c:\archives\2008"

Try
    Dim picList As String() = Directory.GetFiles(sourceDir, "*.jpg")
    Dim txtList As String() = Directory.GetFiles(sourceDir, "*.txt")

    ' Copy picture files.
    For Each f As String In picList
        'Remove path from the file name.
        Dim fName As String = f.Substring(sourceDir.Length + 1)

        ' 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)
    Next

    ' Copy text files.
    For Each f As String In txtList

        'Remove path from the file name.
        Dim fName As String = f.Substring(sourceDir.Length + 1)

        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 copyError As IOException
            Console.WriteLine(copyError.Message)
        End Try
    Next

    For Each f As String In txtList
        File.Delete(f)
    Next

    For Each f As String In picList
        File.Delete(f)
    Next

Catch dirNotFound As DirectoryNotFoundException
    Console.WriteLine(dirNotFound.Message)
End Try

注解

此方法等效于 Copy(String, String, Boolean) 方法重载，overwrite 参数设置为 false。

sourceFileName 和 destFileName 参数可以指定相对路径或绝对路径信息。 相对路径信息解释为相对于当前工作目录。 若要获取当前工作目录，请参阅 Directory.GetCurrentDirectory 方法。 此方法不支持参数中的通配符。

原始文件的属性保留在复制的文件中。

另请参阅

• Move(String, String)
• Move(String, String)
• 文件和流 I/O
• 从文件 读取文本
• 如何：将文本写入文件
• 如何：读取和写入新创建的数据文件

Copy(String, String, Boolean)

Source:

File.cs

将现有文件复制到新文件。 允许覆盖同名文件。

public:
 static void Copy(System::String ^ sourceFileName, System::String ^ destFileName, bool overwrite);

public static void Copy (string sourceFileName, string destFileName, bool overwrite);

static member Copy : string * string * bool -> unit

Public Shared Sub Copy (sourceFileName As String, destFileName As String, overwrite As Boolean)

参数

sourceFileName

String

要复制的文件。

destFileName

String

目标文件的名称。 这不能是目录。

overwrite

Boolean

如果目标文件已存在，则 true 替换目标文件;否则，false。

例外

UnauthorizedAccessException

调用方没有所需的权限。

-或-

destFileName 为只读。

-或-

overwrite true，destFileName 存在且隐藏，但 sourceFileName 不隐藏。

ArgumentException

sourceFileName 或 destFileName 是长度为零的字符串，仅包含空格，或包含一个或多个无效字符。 可以使用 GetInvalidPathChars() 方法查询无效字符。

-或-

sourceFileName 或 destFileName 指定目录。

ArgumentNullException

sourceFileName 或 destFileNamenull。

PathTooLongException

指定的路径、文件名或两者都超过了系统定义的最大长度。

DirectoryNotFoundException

在 sourceFileName 或 destFileName 中指定的路径无效（例如，它位于未映射的驱动器上）。

FileNotFoundException

找不到 sourceFileName。

IOException

destFileName 存在，overwritefalse。

-或-

发生 I/O 错误。

NotSupportedException

sourceFileName 或 destFileName 格式无效。

示例

以下示例将文件复制到 C：\archives\2008 备份文件夹。 它使用 Copy 方法的两个重载，如下所示：

• 它首先使用 File.Copy(String, String) 方法重载复制文本（.txt）文件。 该代码演示此重载不允许覆盖已复制的文件。

然后，它使用 File.Copy(String, String, Boolean) 方法重载复制图片（.jpg 文件）。 该代码演示此重载确实允许覆盖已复制的文件。

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 + 1);

        // 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 + 1);

        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);
}

let sourceDir = @"c:\current"
let backupDir = @"c:\archives\2008"

try
    let picList = Directory.GetFiles(sourceDir, "*.jpg")
    let txtList = Directory.GetFiles(sourceDir, "*.txt")

    // Copy picture files.
    for f in picList do
        // Remove path from the file name.
        let fName = f.Substring(sourceDir.Length + 1)

        // 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.
    for f in txtList do
        // Remove path from the file name.
        let fName = f.Substring(sourceDir.Length + 1)

        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.
        with
        | :? IOException as copyError -> printfn $"{copyError.Message}"

    // Delete source files that were copied.
    for f in txtList do
        File.Delete f

    for f in picList do
        File.Delete f

// Catch exception if the file was already copied.
with
| :? DirectoryNotFoundException as dirNotFound -> printfn $"{dirNotFound.Message}"

Dim sourceDir As String = "c:\current"
Dim backupDir As String = "c:\archives\2008"

Try
    Dim picList As String() = Directory.GetFiles(sourceDir, "*.jpg")
    Dim txtList As String() = Directory.GetFiles(sourceDir, "*.txt")

    ' Copy picture files.
    For Each f As String In picList
        'Remove path from the file name.
        Dim fName As String = f.Substring(sourceDir.Length + 1)

        ' 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)
    Next

    ' Copy text files.
    For Each f As String In txtList

        'Remove path from the file name.
        Dim fName As String = f.Substring(sourceDir.Length + 1)

        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 copyError As IOException
            Console.WriteLine(copyError.Message)
        End Try
    Next

    For Each f As String In txtList
        File.Delete(f)
    Next

    For Each f As String In picList
        File.Delete(f)
    Next

Catch dirNotFound As DirectoryNotFoundException
    Console.WriteLine(dirNotFound.Message)
End Try

注解

sourceFileName 和 destFileName 参数可以指定相对路径或绝对路径信息。 相对路径信息解释为相对于当前工作目录。 此方法不支持参数中的通配符。

原始文件的属性保留在复制的文件中。

有关常见 I/O 任务的列表，请参阅 常见 I/O 任务。

另请参阅

• Move(String, String)
• Move(String, String)
• 文件和流 I/O
• 从文件 读取文本
• 如何：将文本写入文件
• 如何：读取和写入新创建的数据文件