Membuat, menulis, dan membaca file

Artikel
08/25/2023

API penting

Membaca dan menulis file menggunakan objek StorageFile.

Catatan

Untuk sampel lengkap, lihat Sampel akses file.

Prasyarat

Memahami pemrograman asinkron untuk aplikasi Platform Windows Universal (UWP)

Anda dapat mempelajari cara menulis aplikasi asinkron di C# atau Visual Basic, lihat Memanggil API asinkron di C# atau Visual Basic. Untuk mempelajari cara menulis aplikasi asinkron di C++/WinRT, lihat Operasi konkurensi dan asinkron dengan C++/WinRT. Untuk mempelajari cara menulis aplikasi asinkron di C++/CX, lihat Pemrograman asinkron di C++/CX.
Ketahui cara mendapatkan file yang ingin Anda baca, tulis, atau keduanya

Anda dapat mempelajari cara mendapatkan file dengan menggunakan pemilih file di Buka file dan folder dengan pemilih.

Membuat file

Berikut cara membuat file di folder lokal aplikasi. Jika sudah ada, kami menggantinya.

// Create sample file; replace if exists.
Windows.Storage.StorageFolder storageFolder =
    Windows.Storage.ApplicationData.Current.LocalFolder;
Windows.Storage.StorageFile sampleFile =
    await storageFolder.CreateFileAsync("sample.txt",
        Windows.Storage.CreationCollisionOption.ReplaceExisting);

// MainPage.h
#include <winrt/Windows.Storage.h>
...
Windows::Foundation::IAsyncAction ExampleCoroutineAsync()
{
    // Create a sample file; replace if exists.
    Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
    co_await storageFolder.CreateFileAsync(L"sample.txt", Windows::Storage::CreationCollisionOption::ReplaceExisting);
}

// Create a sample file; replace if exists.
StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
concurrency::create_task(storageFolder->CreateFileAsync("sample.txt", CreationCollisionOption::ReplaceExisting));

' Create sample file; replace if exists.
Dim storageFolder As StorageFolder = Windows.Storage.ApplicationData.Current.LocalFolder
Dim sampleFile As StorageFile = Await storageFolder.CreateFileAsync("sample.txt", CreationCollisionOption.ReplaceExisting)

Menulis ke file

Berikut cara menulis ke file yang dapat ditulis pada disk menggunakan kelas StorageFile. Langkah pertama umum untuk setiap cara menulis ke file (kecuali Anda menulis ke file segera setelah membuatnya) adalah mendapatkan file dengan StorageFolder.GetFileAsync.

Windows.Storage.StorageFolder storageFolder =
    Windows.Storage.ApplicationData.Current.LocalFolder;
Windows.Storage.StorageFile sampleFile =
    await storageFolder.GetFileAsync("sample.txt");

// MainPage.h
#include <winrt/Windows.Storage.h>
...
Windows::Foundation::IAsyncAction ExampleCoroutineAsync()
{
    Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
    auto sampleFile{ co_await storageFolder.CreateFileAsync(L"sample.txt", Windows::Storage::CreationCollisionOption::ReplaceExisting) };
    // Process sampleFile
}

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile) 
{
    // Process file
});

Dim storageFolder As StorageFolder = Windows.Storage.ApplicationData.Current.LocalFolder
Dim sampleFile As StorageFile = Await storageFolder.GetFileAsync("sample.txt")

Menulis teks ke file

Tulis teks ke file Anda dengan memanggil metode FileIO.WriteTextAsync.

await Windows.Storage.FileIO.WriteTextAsync(sampleFile, "Swift as a shadow");

// MainPage.h
#include <winrt/Windows.Storage.h>
...
Windows::Foundation::IAsyncAction ExampleCoroutineAsync()
{
    Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
    auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
    // Write text to the file.
    co_await Windows::Storage::FileIO::WriteTextAsync(sampleFile, L"Swift as a shadow");
}

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile) 
{
    //Write text to a file
    create_task(FileIO::WriteTextAsync(sampleFile, "Swift as a shadow"));
});

Await Windows.Storage.FileIO.WriteTextAsync(sampleFile, "Swift as a shadow")

Menulis byte ke file dengan menggunakan buffer (2 langkah)

Pertama, panggil CryptographicBuffer.ConvertStringToBinary untuk mendapatkan buffer byte (berdasarkan string) yang ingin Anda tulis ke file Anda.

var buffer = Windows.Security.Cryptography.CryptographicBuffer.ConvertStringToBinary(
    "What fools these mortals be", Windows.Security.Cryptography.BinaryStringEncoding.Utf8);

// MainPage.h
#include <winrt/Windows.Security.Cryptography.h>
#include <winrt/Windows.Storage.h>
#include <winrt/Windows.Storage.Streams.h>
...
Windows::Foundation::IAsyncAction ExampleCoroutineAsync()
{
    Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
    auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
    // Create the buffer.
    Windows::Storage::Streams::IBuffer buffer{
        Windows::Security::Cryptography::CryptographicBuffer::ConvertStringToBinary(
            L"What fools these mortals be", Windows::Security::Cryptography::BinaryStringEncoding::Utf8)};
    // The code in step 2 goes here.
}

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    // Create the buffer
    IBuffer^ buffer = CryptographicBuffer::ConvertStringToBinary
    ("What fools these mortals be", BinaryStringEncoding::Utf8);
});

Dim buffer = Windows.Security.Cryptography.CryptographicBuffer.ConvertStringToBinary(
    "What fools these mortals be",
    Windows.Security.Cryptography.BinaryStringEncoding.Utf8)

Kemudian tulis byte dari buffer Anda ke file Anda dengan memanggil metode FileIO.WriteBufferAsync.

await Windows.Storage.FileIO.WriteBufferAsync(sampleFile, buffer);

co_await Windows::Storage::FileIO::WriteBufferAsync(sampleFile, buffer);

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    // Create the buffer
    IBuffer^ buffer = CryptographicBuffer::ConvertStringToBinary
    ("What fools these mortals be", BinaryStringEncoding::Utf8);      
    // Write bytes to a file using a buffer
    create_task(FileIO::WriteBufferAsync(sampleFile, buffer));
});

Await Windows.Storage.FileIO.WriteBufferAsync(sampleFile, buffer)

Menulis teks ke file dengan menggunakan aliran (4 langkah)

Pertama, buka file dengan memanggil metode StorageFile.OpenAsync. Ini mengembalikan aliran konten file saat operasi terbuka selesai.

var stream = await sampleFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

// MainPage.h
#include <winrt/Windows.Storage.h>
#include <winrt/Windows.Storage.Streams.h>
...
Windows::Foundation::IAsyncAction ExampleCoroutineAsync()
{
    Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
    auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
    Windows::Storage::Streams::IRandomAccessStream stream{ co_await sampleFile.OpenAsync(Windows::Storage::FileAccessMode::ReadWrite) };
    // The code in step 2 goes here.
}

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    create_task(sampleFile->OpenAsync(FileAccessMode::ReadWrite)).then([sampleFile](IRandomAccessStream^ stream)
    {
        // Process stream
    });
});

Dim stream = Await sampleFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite)

Selanjutnya, dapatkan aliran output dengan memanggil metode IRandomAccessStream.GetOutputStreamAt dari stream. Jika Anda menggunakan C#, maka sertakan ini dalam pernyataan penggunaan untuk mengelola masa pakai aliran output. Jika Anda menggunakan C++/WinRT, Maka Anda dapat mengontrol masa pakainya dengan mengapitnya dalam blok, atau mengaturnya nullptr ke ketika Anda selesai dengannya.

using (var outputStream = stream.GetOutputStreamAt(0))
{
    // We'll add more code here in the next step.
}
stream.Dispose(); // Or use the stream variable (see previous code snippet) with a using statement as well.

Windows::Storage::Streams::IOutputStream outputStream{ stream.GetOutputStreamAt(0) };
// The code in step 3 goes here.

// Add to "Process stream" in part 1
IOutputStream^ outputStream = stream->GetOutputStreamAt(0);

Using outputStream = stream.GetOutputStreamAt(0)
' We'll add more code here in the next step.
End Using

Sekarang tambahkan kode ini (jika Anda menggunakan C#, dalam pernyataan penggunaan yang ada) untuk menulis ke aliran output dengan membuat objek DataWriter baru dan memanggil metode DataWriter.WriteString.

using (var dataWriter = new Windows.Storage.Streams.DataWriter(outputStream))
{
    dataWriter.WriteString("DataWriter has methods to write to various types, such as DataTimeOffset.");
}

Windows::Storage::Streams::DataWriter dataWriter;
dataWriter.WriteString(L"DataWriter has methods to write to various types, such as DataTimeOffset.");
// The code in step 4 goes here.

// Added after code from part 2
DataWriter^ dataWriter = ref new DataWriter(outputStream);
dataWriter->WriteString("DataWriter has methods to write to various types, such as DataTimeOffset.");

Dim dataWriter As New DataWriter(outputStream)
dataWriter.WriteString("DataWriter has methods to write to various types, such as DataTimeOffset.")

Terakhir, tambahkan kode ini (jika Anda menggunakan C#, dalam pernyataan penggunaan dalam) untuk menyimpan teks ke file Anda dengan DataWriter.StoreAsync dan tutup aliran dengan IOutputStream.FlushAsync.

await dataWriter.StoreAsync();
await outputStream.FlushAsync();

dataWriter.StoreAsync();
outputStream.FlushAsync();

// Added after code from part 3
dataWriter->StoreAsync();
outputStream->FlushAsync();

Await dataWriter.StoreAsync()
Await outputStream.FlushAsync()

Praktik terbaik untuk menulis ke file

Untuk detail tambahan dan panduan praktik terbaik, lihat Praktik terbaik untuk menulis ke file.

Membaca dari file

Berikut cara membaca dari file di disk menggunakan kelas StorageFile. Langkah pertama umum untuk setiap cara membaca dari file adalah mendapatkan file dengan StorageFolder.GetFileAsync.

Windows.Storage.StorageFolder storageFolder =
    Windows.Storage.ApplicationData.Current.LocalFolder;
Windows.Storage.StorageFile sampleFile =
    await storageFolder.GetFileAsync("sample.txt");

Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
// Process file

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    // Process file
});

Dim storageFolder As StorageFolder = Windows.Storage.ApplicationData.Current.LocalFolder
Dim sampleFile As StorageFile = Await storageFolder.GetFileAsync("sample.txt")

Membaca teks dari file

Baca teks dari file Anda dengan memanggil metode FileIO.ReadTextAsync.

string text = await Windows.Storage.FileIO.ReadTextAsync(sampleFile);

Windows::Foundation::IAsyncOperation<winrt::hstring> ExampleCoroutineAsync()
{
    Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
    auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
    co_return co_await Windows::Storage::FileIO::ReadTextAsync(sampleFile);
}

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    return FileIO::ReadTextAsync(sampleFile);
});

Dim text As String = Await Windows.Storage.FileIO.ReadTextAsync(sampleFile)

Membaca teks dari file dengan menggunakan buffer (2 langkah)

Pertama, panggil metode FileIO.ReadBufferAsync.

var buffer = await Windows.Storage.FileIO.ReadBufferAsync(sampleFile);

Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
Windows::Storage::Streams::IBuffer buffer{ co_await Windows::Storage::FileIO::ReadBufferAsync(sampleFile) };
// The code in step 2 goes here.

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    return FileIO::ReadBufferAsync(sampleFile);

}).then([](Streams::IBuffer^ buffer)
{
    // Process buffer
});

Dim buffer = Await Windows.Storage.FileIO.ReadBufferAsync(sampleFile)

Kemudian gunakan objek DataReader untuk membaca terlebih dahulu panjang buffer lalu kontennya.

using (var dataReader = Windows.Storage.Streams.DataReader.FromBuffer(buffer))
{
    string text = dataReader.ReadString(buffer.Length);
}

auto dataReader{ Windows::Storage::Streams::DataReader::FromBuffer(buffer) };
winrt::hstring bufferText{ dataReader.ReadString(buffer.Length()) };

// Add to "Process buffer" section from part 1
auto dataReader = DataReader::FromBuffer(buffer);
String^ bufferText = dataReader->ReadString(buffer->Length);

Dim dataReader As DataReader = Windows.Storage.Streams.DataReader.FromBuffer(buffer)
Dim text As String = dataReader.ReadString(buffer.Length)

Membaca teks dari file dengan menggunakan aliran (4 langkah)

Buka aliran untuk file Anda dengan memanggil metode StorageFile.OpenAsync. Ini mengembalikan aliran konten file saat operasi selesai.

var stream = await sampleFile.OpenAsync(Windows.Storage.FileAccessMode.Read);

Windows::Storage::StorageFolder storageFolder{ Windows::Storage::ApplicationData::Current().LocalFolder() };
auto sampleFile{ co_await storageFolder.GetFileAsync(L"sample.txt") };
Windows::Storage::Streams::IRandomAccessStream stream{ co_await sampleFile.OpenAsync(Windows::Storage::FileAccessMode::Read) };
// The code in step 2 goes here.

StorageFolder^ storageFolder = ApplicationData::Current->LocalFolder;
create_task(storageFolder->GetFileAsync("sample.txt")).then([](StorageFile^ sampleFile)
{
    create_task(sampleFile->OpenAsync(FileAccessMode::Read)).then([sampleFile](IRandomAccessStream^ stream)
    {
        // Process stream
    });
});

Dim stream = Await sampleFile.OpenAsync(Windows.Storage.FileAccessMode.Read)

Dapatkan ukuran aliran yang akan digunakan nanti.

ulong size = stream.Size;

uint64_t size{ stream.Size() };
// The code in step 3 goes here.

// Add to "Process stream" from part 1
UINT64 size = stream->Size;

Dim size = stream.Size

Dapatkan aliran input dengan memanggil metode IRandomAccessStream.GetInputStreamAt. Masukkan ini ke dalam pernyataan penggunaan untuk mengelola masa pakai aliran. Tentukan 0 saat Anda memanggil GetInputStreamAt untuk mengatur posisi ke awal aliran.

using (var inputStream = stream.GetInputStreamAt(0))
{
    // We'll add more code here in the next step.
}

Windows::Storage::Streams::IInputStream inputStream{ stream.GetInputStreamAt(0) };
Windows::Storage::Streams::DataReader dataReader{ inputStream };
// The code in step 4 goes here.

// Add after code from part 2
IInputStream^ inputStream = stream->GetInputStreamAt(0);
auto dataReader = ref new DataReader(inputStream);

Using inputStream = stream.GetInputStreamAt(0)
' We'll add more code here in the next step.
End Using

Terakhir, tambahkan kode ini dalam pernyataan penggunaan yang ada untuk mendapatkan objek DataReader pada aliran lalu baca teks dengan memanggil DataReader.LoadAsync dan DataReader.ReadString.

using (var dataReader = new Windows.Storage.Streams.DataReader(inputStream))
{
    uint numBytesLoaded = await dataReader.LoadAsync((uint)size);
    string text = dataReader.ReadString(numBytesLoaded);
}

unsigned int cBytesLoaded{ co_await dataReader.LoadAsync(size) };
winrt::hstring streamText{ dataReader.ReadString(cBytesLoaded) };

// Add after code from part 3
create_task(dataReader->LoadAsync(size)).then([sampleFile, dataReader](unsigned int numBytesLoaded)
{
    String^ streamText = dataReader->ReadString(numBytesLoaded);
});

Dim dataReader As New DataReader(inputStream)
Dim numBytesLoaded As UInteger = Await dataReader.LoadAsync(CUInt(size))
Dim text As String = dataReader.ReadString(numBytesLoaded)

Membuat, menulis, dan membaca file

Prasyarat

Membuat file

Menulis ke file

Membaca dari file

Baca juga

Saran dan Komentar

Saran dan Komentar

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