爲什麼ASCII.GetBytes返回錯誤的字節

Question

我創建一個類並將其轉換爲xml。

的問題是，當我的類XML字符串轉換爲字節
的ASCII.GetBytes中的ascArray

開始返回與
一個多餘的字符一個字節數組，它總是一個？字符，所以XML開始像這樣

?<?xml version="1.0" encoding="utf-8"?> 

爲什麼會發生這種情況？

這是代碼：

WorkItem p = new WorkItem(); 

    // Fill the class with whatever need to be sent to client 
    OneItem posts1 = new OneItem(); 
    posts1.id = "id 1"; 
    posts1.username = "hasse"; 
    posts1.message = "hej again"; 
    posts1.time = "time1"; 
    p.setPost(posts1); 

    OneItem posts2 = new OneItem(); 
    posts2.id = "id 2"; 
    posts2.username = "bella"; 
    posts2.message = "hej again again"; 
    posts2.time = "time2"; 
    p.setPost(posts2); 

    // convert the class WorkItem to xml 
    MemoryStream memoryStream = new MemoryStream(); 
    XmlSerializer xs = new XmlSerializer(typeof(WorkItem)); 
    XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8); 
    xs.Serialize(xmlTextWriter, p); 

    // send the xml version of WorkItem to client 
    byte[] data = memoryStream.ToArray(); 
    clientStream.Write(data, 0, data.Length); 
    Console.WriteLine(" send.." + data); 
    clientStream.Close(); 

Answer 1

我強烈懷疑該數據與byte order mark，無法通過ASCII表示開始。

不清楚爲什麼你要做的是你在做什麼，尤其是在MemoryStream。你爲什麼要創建一個UTF-8編碼的字節數組，然後將其解碼爲一個字符串（並且我們不知道UTF8ByteArrayToString的作用），然後將其轉換回爲字節數組？爲什麼不直接將字節數組直接寫入客戶端？如果你需要數據作爲字符串，我會使用StringWriter的子類，它宣稱它使用UTF-8作爲編碼。如果你不需要需要它作爲一個字符串，只要堅持字節數組。

請注意，即使除了第一個字符外，您已經獲得以UTF-8編碼的XML文檔這一事實意味着字符串中可能還有其他非ASCII字符。你爲什麼在這裏使用ASCII？

編輯：只是要清楚，你從根本上應用有損轉換，和做不必要的。即使你想要的數據的本地副本，你應該有這樣的事情：

// Removed bad try/catch block - don't just catch Exception, and don't 
// just swallow exceptions 
MemoryStream memoryStream = new MemoryStream(); 
XmlSerializer xs = new XmlSerializer(typeof(WorkItem)); 
XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8); 
xs.Serialize(xmlTextWriter, p); 

// Removed pointless conversion to/from string 
// Removed pointless BinaryWriter (just use the stream) 

// An alternative would be memoryStream.WriteTo(clientStream); 
byte[] data = memoryStream.ToArray(); 
clientStream.Write(data, 0, data.Length); 
Console.WriteLine(" send.." + data); 

// Removed Close calls - you should use "using" statements to dispose of 
// streams automatically.