FileInfo.OpenWrite 方法
创建只写 FileStream。
**命名空间:**System.IO
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
Public Function OpenWrite As FileStream
用法
Dim instance As FileInfo
Dim returnValue As FileStream
returnValue = instance.OpenWrite
public FileStream OpenWrite ()
public:
FileStream^ OpenWrite ()
public FileStream OpenWrite ()
public function OpenWrite () : FileStream
返回值
新的只写不共享的 FileStream 对象。
异常
| 异常类型 | 条件 |
|---|---|
path 为只读，或者是一个目录。 |
|
指定的路径无效，比如在未映射的驱动器上。 |
备注
下表列出了其他典型或相关的 I/O 任务的示例。
若要执行此操作... |
请参见本主题中的示例... |
|---|---|
创建文本文件。 |
|
写入文本文件。 |
|
读取文本文件。 |
|
向文件中追加文本。 |
|
重命名或移动文件。 |
|
复制文件。 |
|
获取文件大小。 |
|
获取文件属性。 |
|
设置文件属性。 |
|
确定文件是否存在。 |
|
读取二进制文件。 |
|
写入二进制文件。 |
|
创建目录。 |
示例
下面的示例打开一个文件进行写入操作，随后从该文件中读取。
Imports System
Imports System.IO
Imports System.Text
Public Class Test
Public Shared Sub Main()
Dim path As String = "c:\temp\MyTest.txt"
Dim fi As FileInfo = New FileInfo(path)
Dim fs As FileStream
' Create the file if it does not exist.
If fi.Exists = False Then
fi.Create()
End If
' Open the stream for writing.
fs = fi.OpenWrite()
Dim info As Byte() = _
New UTF8Encoding(True).GetBytes("This is to test the OpenWrite method.")
' Add some information to the file.
fs.Write(info, 0, info.Length)
fs.Close()
'Open the stream and read it back.
fs = fi.OpenRead()
Dim b(1024) As Byte
Dim temp As UTF8Encoding = New UTF8Encoding(True)
Do While fs.Read(b, 0, b.Length) > 0
Console.WriteLine(temp.GetString(b))
Loop
fs.Close()
End Sub
End Class
using System;
using System.IO;
using System.Text;
class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt";
FileInfo fi = new FileInfo(path);
if (!fi.Exists)
{
//Create the file.
fi.Create();
}
// Open the stream for writing.
using (FileStream fs = fi.OpenWrite())
{
Byte[] info =
new UTF8Encoding(true).GetBytes("This is to test the OpenWrite method.");
// Add some information to the file.
fs.Write(info, 0, info.Length);
}
// Open the stream and read it back.
using (FileStream fs = fi.OpenRead())
{
byte[] b = new byte[1024];
UTF8Encoding temp = new UTF8Encoding(true);
while (fs.Read(b,0,b.Length) > 0)
{
Console.WriteLine(temp.GetString(b));
}
}
}
}
using namespace System;
using namespace System::IO;
using namespace System::Text;
int main()
{
String^ path = "c:\\temp\\MyTest.txt";
FileInfo^ fi = gcnew FileInfo( path );
// Create the file if it does not exist.
if ( !fi->Exists )
{
fi->Create();
}
// Open the stream for writing.
{
FileStream^ fs = fi->OpenWrite();
try
{
array<Byte>^info = (gcnew UTF8Encoding( true ))->GetBytes( "This is to test the OpenWrite method." );
// Add some information to the file.
fs->Write( info, 0, info->Length );
}
finally
{
if ( fs )
delete (IDisposable^)fs;
}
}
// Open the stream and read it back.
{
FileStream^ fs = fi->OpenRead();
try
{
array<Byte>^b = gcnew array<Byte>(1024);
UTF8Encoding^ temp = gcnew UTF8Encoding( true );
while ( fs->Read( b, 0, b->Length ) > 0 )
{
Console::WriteLine( temp->GetString( b ) );
}
}
finally
{
if ( fs )
delete (IDisposable^)fs;
}
}
}
import System.*;
import System.IO.*;
import System.Text.*;
class Test
{
public static void main(String[] args)
{
String path = "c:\\temp\\MyTest.txt";
// Delete the file if it exists.
if (!(File.Exists(path))) {
// Create the file.
FileStream fs = File.Create(path);
try {
}
finally {
fs.Dispose();
}
}
// Open the stream for writing.
{
FileStream fs = File.OpenWrite(path);
try {
ubyte info[] = (new UTF8Encoding(true)).GetBytes("This is to "
+ " test the OpenWrite method.");
// Add some information to the file.
fs.Write(info, 0, info.length);
}
finally {
fs.Dispose();
}
}
// Open the stream and read it back.
{
FileStream fs = File.OpenRead(path);
try {
ubyte b[] = new ubyte[1024];
UTF8Encoding temp = new UTF8Encoding(true);
while ((fs.Read(b, 0, b.length) > 0)) {
Console.WriteLine(temp.GetString(b));
}
}
finally {
fs.Dispose();
}
}
} //main
} //Test
.NET Framework 安全性
- FileIOPermission 用于读取和写入文件。关联的枚举：FileIOPermissionAccess.Read、FileIOPermissionAccess.Write
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0
请参见
参考
FileInfo 类
FileInfo 成员
System.IO 命名空间