我想解码Base64编码的字符串,然后将它存储在我的数据库中。如果输入不是Base64编码的,我需要抛出一个错误。
我如何检查一个字符串是否被Base64编码?
我想解码Base64编码的字符串,然后将它存储在我的数据库中。如果输入不是Base64编码的,我需要抛出一个错误。
我如何检查一个字符串是否被Base64编码?
当前回答
import java.util.Base64;
public static String encodeBase64(String s) {
return Base64.getEncoder().encodeToString(s.getBytes());
}
public static String decodeBase64(String s) {
try {
if (isBase64(s)) {
return new String(Base64.getDecoder().decode(s));
} else {
return s;
}
} catch (Exception e) {
return s;
}
}
public static boolean isBase64(String s) {
String pattern = "^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$";
Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(s);
return m.find();
}
其他回答
Function Check_If_Base64(ByVal msgFile As String) As Boolean
Dim I As Long
Dim Buffer As String
Dim Car As String
Check_If_Base64 = True
Buffer = Leggi_File(msgFile)
Buffer = Replace(Buffer, vbCrLf, "")
For I = 1 To Len(Buffer)
Car = Mid(Buffer, I, 1)
If (Car < "A" Or Car > "Z") _
And (Car < "a" Or Car > "z") _
And (Car < "0" Or Car > "9") _
And (Car <> "+" And Car <> "/" And Car <> "=") Then
Check_If_Base64 = False
Exit For
End If
Next I
End Function
Function Leggi_File(PathAndFileName As String) As String
Dim FF As Integer
FF = FreeFile()
Open PathAndFileName For Binary As #FF
Leggi_File = Input(LOF(FF), #FF)
Close #FF
End Function
对于Java风格,我实际上使用以下正则表达式:
"([A-Za-z0-9+]{4})*([A-Za-z0-9+]{3}=|[A-Za-z0-9+]{2}(==){0,2})?"
在某些情况下,==也是可选的。
最好!
尝试使用前面提到的正则表达式:
String regex = "^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$";
if("TXkgdGVzdCBzdHJpbmc/".matches(regex)){
System.out.println("it's a Base64");
}
...我们还可以做一个简单的验证,比如,如果它有空格,它就不能是Base64:
String myString = "Hello World";
if(myString.contains(" ")){
System.out.println("Not B64");
}else{
System.out.println("Could be B64 encoded, since it has no spaces");
}
Base64有许多变体,所以考虑只确定您的字符串是否类似于您期望处理的变体。因此,您可能需要根据索引和填充字符(即+,/,=)调整下面的正则表达式。
class String
def resembles_base64?
self.length % 4 == 0 && self =~ /^[A-Za-z0-9+\/=]+\Z/
end
end
用法:
raise 'the string does not resemble Base64' unless my_string.resembles_base64?
这在Python中是有效的:
import base64
def IsBase64(str):
try:
base64.b64decode(str)
return True
except Exception as e:
return False
if IsBase64("ABC"):
print("ABC is Base64-encoded and its result after decoding is: " + str(base64.b64decode("ABC")).replace("b'", "").replace("'", ""))
else:
print("ABC is NOT Base64-encoded.")
if IsBase64("QUJD"):
print("QUJD is Base64-encoded and its result after decoding is: " + str(base64.b64decode("QUJD")).replace("b'", "").replace("'", ""))
else:
print("QUJD is NOT Base64-encoded.")
IsBase64("string here")如果这里的字符串是base64编码的则返回true,如果这里的字符串不是base64编码的则返回false。