Java 中的 UTF-16 编码与 C# 的比较
我正在尝试读取 UTF-16 编码方案中的字符串并对其执行 MD5 哈希。但奇怪的是，当我尝试这样做时，Java 和 C# 返回了不同的结果。
以下是 Java 中的代码片段：
public static void main(String[] args) {
String str = "preparar mantecado con coca cola";
try {
MessageDigest digest = MessageDigest.getInstance("MD5");
digest.update(str.getBytes("UTF-16"));
byte[] hash = digest.digest();
String output = "";
for(byte b: hash){
output += Integer.toString( ( b & 0xff ) + 0x100, 16).substring( 1 );
}
System.out.println(output);
} catch (Exception e) {
}
}
输出为： 249ece65145dca34ed310445758e5504
以下是 C# 中的代码片段：
public static string GetMD5Hash()
{
string input = "preparar mantecado con coca cola";
System.Security.Cryptography.MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
byte[] bs = System.Text.Encoding.Unicode.GetBytes(input);
bs = x.ComputeHash(bs);
System.Text.StringBuilder s = new System.Text.StringBuilder();
foreach (byte b in bs)
{
s.Append(b.ToString("x2").ToLower());
}
string output= s.ToString();
Console.WriteLine(output);
}
输出因为这是： c04d0f518ba2555977fa1ed7f93ae2b3
我不确定为什么输出不一样。我们如何更改上面的代码，以便它们都返回相同的输出？
I am trying to read a String in UTF-16 encoding scheme and perform MD5 hashing on it. But strangely, Java and C# are returning different results when I try to do it.
The following is the piece of code in Java:
public static void main(String[] args) {
String str = "preparar mantecado con coca cola";
try {
MessageDigest digest = MessageDigest.getInstance("MD5");
digest.update(str.getBytes("UTF-16"));
byte[] hash = digest.digest();
String output = "";
for(byte b: hash){
output += Integer.toString( ( b & 0xff ) + 0x100, 16).substring( 1 );
}
System.out.println(output);
} catch (Exception e) {
}
}
The output for this is: 249ece65145dca34ed310445758e5504
The following is the piece of code in C#:
public static string GetMD5Hash()
{
string input = "preparar mantecado con coca cola";
System.Security.Cryptography.MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
byte[] bs = System.Text.Encoding.Unicode.GetBytes(input);
bs = x.ComputeHash(bs);
System.Text.StringBuilder s = new System.Text.StringBuilder();
foreach (byte b in bs)
{
s.Append(b.ToString("x2").ToLower());
}
string output= s.ToString();
Console.WriteLine(output);
}
The output for this is: c04d0f518ba2555977fa1ed7f93ae2b3
I am not sure, why the outputs are not the same. How do we change the above piece of code, so that both of them return the same output?
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评论（3）
UTF-16 != UTF-16。
在 Java 中，
getBytes("UTF-16")返回带有可选字节排序标记的大端表示形式。 C# 的System.Text.Encoding.Unicode.GetBytes返回小端表示形式。我无法从这里检查您的代码，但我认为您需要准确指定转换。在 Java 版本中尝试
getBytes("UTF-16LE")。UTF-16 != UTF-16.
In Java,
getBytes("UTF-16")returns an a big-endian representation with optional byte-ordering mark. C#'sSystem.Text.Encoding.Unicode.GetBytesreturns a little-endian representation. I can't check your code from here, but I think you'll need to specify the conversion precisely.Try
getBytes("UTF-16LE")in the Java version.我能找到的第一件事（这可能不是唯一的问题）是 C# 的 Encoding.Unicode.GetBytes() 是小尾数，而 Java 的自然字节顺序是大尾数。
The first thing I can find, and this might not be the only problem, is that C#'s Encoding.Unicode.GetBytes() is littleendian, while Java's natural byte order is bigendian.
您可以使用 System.Text.Enconding.Unicode.GetString(byte[]) 来从字节转换回字符串。通过这种方式，您可以确保所有事情都以 Unicode 编码进行。
You could use the
System.Text.Enconding.Unicode.GetString(byte[])to convert back from byte to string. In this way you're sure that all happens in Unicode encoding.