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  • 背水一战 Windows 10 (89)

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    背水一战 Windows 10 (89) - 文件系统: 读写文本数据, 读写二进制数据, 读写流数据



    作者:webabcd


    介绍
    背水一战 Windows 10 之 文件系统

    • 读写文本数据
    • 读写二进制数据
    • 读写流数据



    示例
    1、演示如何读写文本数据
    FileSystem/ReadWriteText.xaml

    <Page
        x:Class="Windows10.FileSystem.ReadWriteText"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:Windows10.FileSystem"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
    
        <Grid Background="Transparent">
            <StackPanel Margin="10 0 10 10">
    
                <TextBlock Name="lblMsg" Margin="5" />
    
                <Button Name="btnWriteText" Content="Write Text" Click="btnWriteText_Click" Margin="5" />
    
                <Button Name="btnReadText" Content="Read Text" Click="btnReadText_Click" Margin="5" />
    
            </StackPanel>
        </Grid>
    </Page>

    FileSystem/ReadWriteText.xaml.cs

    /*
     * 演示如何读写文本数据
     *     
     * FileIO - 用于读写 IStorageFile 对象的帮助类
     *     WriteTextAsync() - 将指定的文本数据写入到指定的文件
     *     AppendTextAsync() - 将指定的文本数据追加到指定的文件
     *     WriteLinesAsync() - 将指定的多段文本数据写入到指定的文件
     *     AppendLinesAsync() - 将指定的多段文本数据追加到指定的文件
     *     ReadTextAsync() - 获取指定的文件中的文本数据
     *     ReadLinesAsync() - 获取指定的文件中的文本数据,返回的是一行一行的数据
     */
    
    using System;
    using Windows.Storage;
    using Windows.UI.Xaml;
    using Windows.UI.Xaml.Controls;
    
    namespace Windows10.FileSystem
    {
        public sealed partial class ReadWriteText : Page
        {
            public ReadWriteText()
            {
                this.InitializeComponent();
            }
    
            private async void btnWriteText_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下创建指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.CreateFileAsync("webabcdText.txt", CreationCollisionOption.ReplaceExisting);
    
                // 在指定的文件中写入指定的文本
                string textContent = "I am webabcd";
                await FileIO.WriteTextAsync(storageFile, textContent, Windows.Storage.Streams.UnicodeEncoding.Utf8); // 编码为 UnicodeEncoding.Utf8
    
                lblMsg.Text = "写入成功";
            }
    
            private async void btnReadText_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下获取指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.GetFileAsync("webabcdText.txt");
    
                if (storageFile != null)
                {
                    // 获取指定的文件中的文本内容
                    string textContent = await FileIO.ReadTextAsync(storageFile, Windows.Storage.Streams.UnicodeEncoding.Utf8); // 编码为 UnicodeEncoding.Utf8
                    lblMsg.Text = "读取结果:" + textContent;
                }
            }
        }
    }


    2、演示如何读写二进制数据
    FileSystem/ReadWriteBinary.xaml

    <Page
        x:Class="Windows10.FileSystem.ReadWriteBinary"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:Windows10.FileSystem"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
    
        <Grid Background="Transparent">
            <StackPanel Margin="10 0 10 10">
    
                <TextBlock Name="lblMsg" Margin="5" />
    
                <Button Name="btnWriteBinary" Content="Write Binary" Click="btnWriteBinary_Click" Margin="5" />
    
                <Button Name="btnReadBinary" Content="Read Binary" Click="btnReadBinary_Click" Margin="5" />
    
            </StackPanel>
        </Grid>
    </Page>

    FileSystem/ReadWriteBinary.xaml.cs

    /*
     * 演示如何读写二进制数据
     * 
     * FileIO - 用于读写 IStorageFile 对象的帮助类
     *     WriteBufferAsync() - 将指定的二进制数据写入指定的文件
     *     ReadBufferAsync() - 获取指定的文件中的二进制数据
     *     
     * IBuffer - 字节数组
     */
    
    using System;
    using Windows.Storage;
    using Windows.Storage.Streams;
    using Windows.UI.Xaml;
    using Windows.UI.Xaml.Controls;
    
    namespace Windows10.FileSystem
    {
        public sealed partial class ReadWriteBinary : Page
        {
            public ReadWriteBinary()
            {
                this.InitializeComponent();
            }
    
            private async void btnWriteBinary_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下创建指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.CreateFileAsync("webabcdBinary.txt", CreationCollisionOption.ReplaceExisting);
    
                // 将字符串转换成二进制数据,并保存到指定文件
                string textContent = "I am webabcd";
                IBuffer buffer = ConverterHelper.String2Buffer(textContent);
                await FileIO.WriteBufferAsync(storageFile, buffer);
    
                lblMsg.Text = "写入成功";
            }
    
            private async void btnReadBinary_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下获取指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.GetFileAsync("webabcdBinary.txt");
    
                if (storageFile != null)
                {
                    // 获取指定文件中的二进制数据,将其转换成字符串并显示
                    IBuffer buffer = await FileIO.ReadBufferAsync(storageFile);
                    string textContent = ConverterHelper.Buffer2String(buffer);
    
                    lblMsg.Text = "读取结果:" + textContent;
                }
            }
        }
    }


    3、演示如何读写流数据
    FileSystem/ReadWriteStream.xaml

    <Page
        x:Class="Windows10.FileSystem.ReadWriteStream"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:Windows10.FileSystem"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
    
        <Grid Background="Transparent">
            <StackPanel Margin="10 0 10 10">
    
                <TextBlock Name="lblMsg" Margin="5" />
    
                <Button Name="btnWriteStream1" Content="Write Stream(通过 IRandomAccessStream 写)" Click="btnWriteStream1_Click" Margin="5" />
    
                <Button Name="btnWriteStream2" Content="Write Stream(通过 StorageStreamTransaction 写)" Click="btnWriteStream2_Click" Margin="5" />
    
                <Button Name="btnReadStream" Content="Read Stream" Click="btnReadStream_Click" Margin="5" />
    
            </StackPanel>
        </Grid>
    </Page>

    FileSystem/ReadWriteStream.xaml.cs

    /*
     * 演示如何读写流数据
     * 
     * IBuffer - 字节数组
     * 
     * IInputStream - 支持读取的流
     * IOutputStream - 支持写入的流
     * IRandomAccessStream - 支持读取和写入的流,其继承自 IInputStream 和 IOutputStream
     * 
     * DataReader - 数据读取器,用于从数据流中读取数据
     *     LoadAsync() - 从数据流中加载指定长度的数据到缓冲区
     *     ReadInt32(), ReadByte(), ReadString() 等 - 从缓冲区中读取数据
     * DataWriter - 数据写入器,用于将数据写入数据流
     *     WriteInt32(), WriteByte(), WriteString() 等 - 将数据写入缓冲区
     *     StoreAsync() - 将缓冲区中的数据保存到数据流
     * 
     * StorageStreamTransaction - 用于写数据流到文件的类(它写文件的方式是:先写临时文件,然后临时文件重命名)
     *     Stream - 数据流(只读)
     *     CommitAsync - 重命名临时文件   
     *     
     * StorageFile - 文件操作类
     *     public IAsyncOperation<IRandomAccessStream> OpenAsync(FileAccessMode accessMode) - 打开文件,返回 IRandomAccessStream 对象
     *     public IAsyncOperation<IRandomAccessStream> OpenAsync(FileAccessMode accessMode, StorageOpenOptions options) - 打开文件,返回 IRandomAccessStream 对象
     *         FileAccessMode.Read - 返回的流可读,不可写
     *         FileAccessMode.ReadWrite - 返回的流可读,可写
     *         StorageOpenOptions.AllowOnlyReaders - 其他调用者可读不可写
     *         StorageOpenOptions.AllowReadersAndWriters - 其他调用者可读可写
     *     public IAsyncOperation<StorageStreamTransaction> OpenTransactedWriteAsync() - 打开文件,返回 StorageStreamTransaction 对象
     *     public IAsyncOperation<StorageStreamTransaction> OpenTransactedWriteAsync(StorageOpenOptions options) - 打开文件,返回 StorageStreamTransaction 对象 
     */
    
    using System;
    using Windows.Storage;
    using Windows.Storage.Streams;
    using Windows.UI.Xaml;
    using Windows.UI.Xaml.Controls;
    
    namespace Windows10.FileSystem
    {
        public sealed partial class ReadWriteStream : Page
        {
            public ReadWriteStream()
            {
                this.InitializeComponent();
            }
    
            // Write Stream(通过 IRandomAccessStream 写)
            private async void btnWriteStream1_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下创建指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.CreateFileAsync("webabcdStream.txt", CreationCollisionOption.ReplaceExisting);
    
                string textContent = "I am webabcd(IRandomAccessStream)";
                if (storageFile != null)
                {
                    using (IRandomAccessStream randomStream = await storageFile.OpenAsync(FileAccessMode.ReadWrite))
                    {
                        using (DataWriter dataWriter = new DataWriter(randomStream))
                        {
                            // 将字符串写入数据流
                            dataWriter.WriteString(textContent);
    
                            // 将数据流写入文件
                            await dataWriter.StoreAsync();
    
                            lblMsg.Text = "写入成功";
                        }
                    }
                }
            }
    
            // Write Stream(通过 StorageStreamTransaction 写)
            private async void btnWriteStream2_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下创建指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.CreateFileAsync("webabcdStream.txt", CreationCollisionOption.ReplaceExisting);
    
                string textContent = "I am webabcd(StorageStreamTransaction)";
    
                using (StorageStreamTransaction transaction = await storageFile.OpenTransactedWriteAsync())
                {
                    using (DataWriter dataWriter = new DataWriter(transaction.Stream))
                    {
                        // 将字符串写入数据流
                        dataWriter.WriteString(textContent);
    
                        // 使用 StorageStreamTransaction 方式的话,调用 DataWriter 的 StoreAsync() 方法的作用是把数据写入临时文件
                        // 以本例为例,这个临时文件就是同目录下名为 webabcdStream.txt.~tmp 的文件。只要不调用 CommitAsync() 方法的话就会看到
                        // 返回值为写入数据的大小,需要通过此值更新 StorageStreamTransaction 中的 Stream 的大小
                        transaction.Stream.Size = await dataWriter.StoreAsync();
    
                        // 重命名临时文件
                        await transaction.CommitAsync();
    
                        lblMsg.Text = "写入成功";
                    }
                }
            }
    
            private async void btnReadStream_Click(object sender, RoutedEventArgs e)
            {
                // 在指定的目录下获取指定的文件
                StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null, KnownFolderId.DocumentsLibrary);
                StorageFile storageFile = await storageFolder.GetFileAsync("webabcdStream.txt");
    
                if (storageFile != null)
                {
                    using (IRandomAccessStream randomStream = await storageFile.OpenAsync(FileAccessMode.Read))
                    {
                        using (DataReader dataReader = new DataReader(randomStream))
                        {
                            ulong size = randomStream.Size;
                            if (size <= uint.MaxValue)
                            {
                                // 从数据流中读取数据
                                uint numBytesLoaded = await dataReader.LoadAsync((uint)size);
    
                                // 将读取到的数据转换为字符串
                                string fileContent = dataReader.ReadString(numBytesLoaded);
    
                                lblMsg.Text = "读取结果:" + fileContent;
                            }
                        }
                    }
                }
            }
        }
    }



    OK
    [源码下载]

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  • 原文地址:https://www.cnblogs.com/webabcd/p/9181360.html
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