How do you get a string from a MemoryStream?
如果给我一个我知道已经被一个
此示例演示如何将字符串读写到MemoryStream。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | Imports System.IO Module Module1 Sub Main() ' We don't need to dispose any of the MemoryStream ' because it is a managed object. However, just for ' good practice, we'll close the MemoryStream. Using ms As New MemoryStream Dim sw As New StreamWriter(ms) sw.WriteLine("Hello World") ' The string is currently stored in the ' StreamWriters buffer. Flushing the stream will ' force the string into the MemoryStream. sw.Flush() ' If we dispose the StreamWriter now, it will close ' the BaseStream (which is our MemoryStream) which ' will prevent us from reading from our MemoryStream 'sw.Dispose() ' The StreamReader will read from the current ' position of the MemoryStream which is currently ' set at the end of the string we just wrote to it. ' We need to set the position to 0 in order to read ' from the beginning. ms.Position = 0 Dim sr As New StreamReader(ms) Dim myStr = sr.ReadToEnd() Console.WriteLine(myStr) ' We can dispose our StreamWriter and StreamReader ' now, though this isn't necessary (they don't hold ' any resources open on their own). sw.Dispose() sr.Dispose() End Using Console.WriteLine("Press any key to continue.") Console.ReadKey() End Sub End Module |
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您也可以使用
1 | Encoding.ASCII.GetString(ms.ToArray()); |
我不认为这会降低效率,但我不能发誓。它还允许您选择不同的编码,而使用streamreader则必须将其指定为参数。
使用streamreader将memoryStream转换为字符串。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | <Extension()> _ Public Function ReadAll(ByVal memStream As MemoryStream) As String ' Reset the stream otherwise you will just get an empty string. ' Remember the position so we can restore it later. Dim pos = memStream.Position memStream.Position = 0 Dim reader As New StreamReader(memStream) Dim str = reader.ReadToEnd() ' Reset the position so that subsequent writes are correct. memStream.Position = pos Return str End Function |
使用streamreader,然后可以使用返回字符串的readtoend方法。
以前的解决方案在涉及编码的情况下不起作用。这里有一个"现实生活"的例子,如何正确地做到这一点…
1 2 3 4 5 6 7 8 | using(var stream = new System.IO.MemoryStream()) { var serializer = new DataContractJsonSerializer(typeof(IEnumerable<ExportData>), new[]{typeof(ExportData)}, Int32.MaxValue, true, null, false); serializer.WriteObject(stream, model); var jsonString = Encoding.Default.GetString((stream.ToArray())); } |
1 2 3 4 5 6 | byte[] array = Encoding.ASCII.GetBytes("MyTest1 - MyTest2"); MemoryStream streamItem = new MemoryStream(array); // convert to string StreamReader reader = new StreamReader(streamItem); string text = reader.ReadToEnd(); |
在这种情况下,如果您真的想用一种简单的方法在
1 2 3 4 5 6 7 8 9 | public static class SetExtensions { public static string ReadToEnd(this MemoryStream BASE) { BASE.Position = 0; StreamReader R = new StreamReader(BASE); return R.ReadToEnd(); } } |
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你可以这样使用这个方法:
1 2 3 4 5 6 7 8 9 10 | using (MemoryStream m = new MemoryStream()) { //for example i want to serialize an object into MemoryStream //I want to use XmlSeralizer XmlSerializer xs = new XmlSerializer(_yourVariable.GetType()); xs.Serialize(m, _yourVariable); //the easy way to use ReadToEnd method in MemoryStream MessageBox.Show(m.ReadToEnd()); } |
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此示例演示如何从memoryStream读取字符串,其中我使用了序列化(使用DataContractJSonSerializer),将字符串从某个服务器传递到客户端,然后,如何从作为参数传递的字符串恢复memoryStream,然后反序列化memoryStream。
我使用了不同职位的一部分来执行这个示例。
希望这有帮助。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 | using System; using System.Collections.Generic; using System.IO; using System.Runtime.Serialization; using System.Runtime.Serialization.Json; using System.Threading; namespace JsonSample { class Program { static void Main(string[] args) { var phones = new List<Phone> { new Phone { Type = PhoneTypes.Home, Number ="28736127" }, new Phone { Type = PhoneTypes.Movil, Number ="842736487" } }; var p = new Person { Id = 1, Name ="Person 1", BirthDate = DateTime.Now, Phones = phones }; Console.WriteLine("New object 'Person' in the server side:"); Console.WriteLine(string.Format("Id: {0}, Name: {1}, Birthday: {2}.", p.Id, p.Name, p.BirthDate.ToShortDateString())); Console.WriteLine(string.Format("Phone: {0} {1}", p.Phones[0].Type.ToString(), p.Phones[0].Number)); Console.WriteLine(string.Format("Phone: {0} {1}", p.Phones[1].Type.ToString(), p.Phones[1].Number)); Console.Write(Environment.NewLine); Thread.Sleep(2000); var stream1 = new MemoryStream(); var ser = new DataContractJsonSerializer(typeof(Person)); ser.WriteObject(stream1, p); stream1.Position = 0; StreamReader sr = new StreamReader(stream1); Console.Write("JSON form of Person object:"); Console.WriteLine(sr.ReadToEnd()); Console.Write(Environment.NewLine); Thread.Sleep(2000); var f = GetStringFromMemoryStream(stream1); Console.Write(Environment.NewLine); Thread.Sleep(2000); Console.WriteLine("Passing string parameter from server to client..."); Console.Write(Environment.NewLine); Thread.Sleep(2000); var g = GetMemoryStreamFromString(f); g.Position = 0; var ser2 = new DataContractJsonSerializer(typeof(Person)); var p2 = (Person)ser2.ReadObject(g); Console.Write(Environment.NewLine); Thread.Sleep(2000); Console.WriteLine("New object 'Person' arrived to the client:"); Console.WriteLine(string.Format("Id: {0}, Name: {1}, Birthday: {2}.", p2.Id, p2.Name, p2.BirthDate.ToShortDateString())); Console.WriteLine(string.Format("Phone: {0} {1}", p2.Phones[0].Type.ToString(), p2.Phones[0].Number)); Console.WriteLine(string.Format("Phone: {0} {1}", p2.Phones[1].Type.ToString(), p2.Phones[1].Number)); Console.Read(); } private static MemoryStream GetMemoryStreamFromString(string s) { var stream = new MemoryStream(); var sw = new StreamWriter(stream); sw.Write(s); sw.Flush(); stream.Position = 0; return stream; } private static string GetStringFromMemoryStream(MemoryStream ms) { ms.Position = 0; using (StreamReader sr = new StreamReader(ms)) { return sr.ReadToEnd(); } } } [DataContract] internal class Person { [DataMember] public int Id { get; set; } [DataMember] public string Name { get; set; } [DataMember] public DateTime BirthDate { get; set; } [DataMember] public List<Phone> Phones { get; set; } } [DataContract] internal class Phone { [DataMember] public PhoneTypes Type { get; set; } [DataMember] public string Number { get; set; } } internal enum PhoneTypes { Home = 1, Movil = 2 } } |
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为什么不在memoryStream类型上创建一个好的扩展方法呢?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | public static class MemoryStreamExtensions { static object streamLock = new object(); public static void WriteLine(this MemoryStream stream, string text, bool flush) { byte[] bytes = Encoding.UTF8.GetBytes(text + Environment.NewLine); lock (streamLock) { stream.Write(bytes, 0, bytes.Length); if (flush) { stream.Flush(); } } } public static void WriteLine(this MemoryStream stream, string formatString, bool flush, params string[] strings) { byte[] bytes = Encoding.UTF8.GetBytes(String.Format(formatString, strings) + Environment.NewLine); lock (streamLock) { stream.Write(bytes, 0, bytes.Length); if (flush) { stream.Flush(); } } } public static void WriteToConsole(this MemoryStream stream) { lock (streamLock) { long temporary = stream.Position; stream.Position = 0; using (StreamReader reader = new StreamReader(stream, Encoding.UTF8, false, 0x1000, true)) { string text = reader.ReadToEnd(); if (!String.IsNullOrEmpty(text)) { Console.WriteLine(text); } } stream.Position = temporary; } } } |
当然,在将这些方法与标准方法结合使用时要小心。:)。
Brian答案的一个稍微修改过的版本允许可选的读启动管理,这似乎是最简单的方法。可能不是最有效的,但易于理解和使用。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | Public Function ReadAll(ByVal memStream As MemoryStream, Optional ByVal startPos As Integer = 0) As String ' reset the stream or we'll get an empty string returned ' remember the position so we can restore it later Dim Pos = memStream.Position memStream.Position = startPos Dim reader As New StreamReader(memStream) Dim str = reader.ReadToEnd() ' reset the position so that subsequent writes are correct memStream.Position = Pos Return str End Function |
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