C# Base64 编码字节数组的有效方法？
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An efficient way to Base64 encode a byte array?
提问by sternr
I have a byte[]and I'm looking for the most efficient way to base64 encode it.
我有一个byte[]，我正在寻找对它进行 base64 编码的最有效方法。
The problem is that the built in .Net method Convert.FromBase64CharArrayrequires a char[]as an input, and converting my byte[]to a char[]just to convert it again to a base64 encoded array seems pretty stupid.
问题是内置的 .Net 方法Convert.FromBase64CharArray需要 achar[]作为输入，而将 my 转换byte[]为 achar[]只是为了将其再次转换为 base64 编码数组似乎很愚蠢。
Is there any more direct way to do it?
有没有更直接的方法来做到这一点？
[[EDIT:]] I'll expaling what I want to acheive better - I have a byte[]and I need to return a new base64 encoded byte[]
[[编辑：]]我会解释我想要更好的实现 - 我有一个byte[]，我需要返回一个新的base64编码byte[]
采纳答案by Amit Bens
Here is the code to base64 encode directly to byte array (tested to be performing +-10% of .Net Implementation, but allocates half the memory):
下面是将 base64 直接编码为字节数组的代码（测试为执行 +-10% 的 .Net 实现，但分配了一半的内存）：
static public void testBase64EncodeToBuffer()
{
for (int i = 1; i < 200; ++i)
{
// prep test data
byte[] testData = new byte[i];
for (int j = 0; j < i; ++j)
testData[j] = (byte)(j ^ i);
// test
testBase64(testData);
}
}
static void testBase64(byte[] data)
{
if (!appendBase64(data, 0, data.Length, false).SequenceEqual(System.Text.Encoding.ASCII.GetBytes(Convert.ToBase64String(data)))) throw new Exception("Base 64 encoding failed);
}
static public byte[] appendBase64(byte[] data
, int offset
, int size
, bool addLineBreaks = false)
{
byte[] buffer;
int bufferPos = 0;
int requiredSize = (4 * ((size + 2) / 3));
// size/76*2 for 2 line break characters
if (addLineBreaks) requiredSize += requiredSize + (requiredSize / 38);
buffer = new byte[requiredSize];
UInt32 octet_a;
UInt32 octet_b;
UInt32 octet_c;
UInt32 triple;
int lineCount = 0;
int sizeMod = size - (size % 3);
// adding all data triplets
for (; offset < sizeMod;)
{
octet_a = data[offset++];
octet_b = data[offset++];
octet_c = data[offset++];
triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c;
buffer[bufferPos++] = base64EncodingTable[(triple >> 3 * 6) & 0x3F];
buffer[bufferPos++] = base64EncodingTable[(triple >> 2 * 6) & 0x3F];
buffer[bufferPos++] = base64EncodingTable[(triple >> 1 * 6) & 0x3F];
buffer[bufferPos++] = base64EncodingTable[(triple >> 0 * 6) & 0x3F];
if (addLineBreaks)
{
if (++lineCount == 19)
{
buffer[bufferPos++] = 13;
buffer[bufferPos++] = 10;
lineCount = 0;
}
}
}
// last bytes
if (sizeMod < size)
{
octet_a = offset < size ? data[offset++] : (UInt32)0;
octet_b = offset < size ? data[offset++] : (UInt32)0;
octet_c = (UInt32)0; // last character is definitely padded
triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c;
buffer[bufferPos++] = base64EncodingTable[(triple >> 3 * 6) & 0x3F];
buffer[bufferPos++] = base64EncodingTable[(triple >> 2 * 6) & 0x3F];
buffer[bufferPos++] = base64EncodingTable[(triple >> 1 * 6) & 0x3F];
buffer[bufferPos++] = base64EncodingTable[(triple >> 0 * 6) & 0x3F];
// add padding '='
sizeMod = size % 3;
// last character is definitely padded
buffer[bufferPos - 1] = (byte)'=';
if (sizeMod == 1) buffer[bufferPos - 2] = (byte)'=';
}
return buffer;
}
回答by Stephan Schinkel
Byte[] -> String:use system.convert.tobase64string
字节[] -> 字符串：使用 system.convert.tobase64string
Convert.ToBase64String(byte[] data)
String -> Byte[]:use system.convert.frombase64string
字符串 -> 字节 []：使用 system.convert.frombase64string
Convert.FromBase64String(string data)
回答by Eren Ers?nmez
Base64 is a way to represent bytes in a textual form (as a string). So there is no such thing as a Base64 encoded byte[]. You'd have a base64 encoded string, which you could decodeback to a byte[].
Base64 是一种以文本形式（作为字符串）表示字节的方法。所以没有 Base64 编码的 byte[] 这样的东西。您将有一个base64 编码的 string，您可以将其解码回byte[].
However, if you wantto end up with a byte array, you could take the base64 encoded string and convert it to a byte array, like:
但是，如果你想得到一个字节数组，你可以使用 base64 编码的字符串并将其转换为一个字节数组，例如：
string base64String = Convert.ToBase64String(bytes);
byte[] stringBytes = Encoding.ASCII.GetBytes(base64String);
This, however, makes no sense because the best way to represent a byte[] as a byte[], is the byte[] itself :)
然而，这是没有意义的，因为将 byte[] 表示为 byte[] 的最佳方式是 byte[] 本身:)
回答by Midrel
You could use the String Convert.ToBase64String(byte[]) to encode the byte array into a base64 string, then Byte[] Convert.FromBase64String(string) to convert the resulting string back into a byte array.
您可以使用 String Convert.ToBase64String(byte[]) 将字节数组编码为 base64 字符串，然后使用 Byte[] Convert.FromBase64String(string) 将结果字符串转换回字节数组。
回答by Simon Whitehead
Based on your edit and comments.. would this be what you're after?
根据您的编辑和评论……这就是您所追求的吗？
byte[] newByteArray = UTF8Encoding.UTF8.GetBytes(Convert.ToBase64String(currentByteArray));
回答by BlueM
byte[] base64EncodedStringBytes = Encoding.ASCII.GetBytes(Convert.ToBase64String(binaryData))
回答by Debashis Nandi
public void ProcessRequest(HttpContext context)
{
string constring = ConfigurationManager.ConnectionStrings["SQL_Connection_String"].ConnectionString;
SqlConnection conn = new SqlConnection(constring);
conn.Open();
SqlCommand cmd = new SqlCommand("select image1 from TestGo where TestId=1", conn);
SqlDataReader dr = cmd.ExecuteReader();
dr.Read();
MemoryStream str = new MemoryStream();
context.Response.Clear();
Byte[] bytes = (Byte[])dr[0];
string d = System.Text.Encoding.Default.GetString(bytes);
byte[] bytes2 = Convert.FromBase64String(d);
//context.Response.Write(d);
Image img = Image.FromStream(new MemoryStream(bytes2));
img.Save(context.Response.OutputStream, ImageFormat.Png);
context.Response.Flush();
str.WriteTo(context.Response.OutputStream);
str.Dispose();
str.Close();
conn.Close();
context.Response.End();
}
