1 /// <summary>自定义包含指定字符的base64工具</summary>
2 internal static class Base64Helper
3 {
4 static readonly string base64Table =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-";
5 static readonly int[] base64Index =
new int[]
6 {
7 -
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,
8 -
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,-
1,
9 -
1,
63,-
1,-
1,
52,
53,
54,
55,
56,
57,
58,
59,
60,
61,-
1,-
1,-
1,-
1,-
1,-
1,-
1,
0,
1,
10 2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12,
13,
14,
15,
16,
17,
18,
19,
20,
21,
22,
23,
24,
25,-
1,
11 -
1,-
1,-
1,
62,-
1,
26,
27,
28,
29,
30,
31,
32,
33,
34,
35,
36,
37,
38,
39,
40,
41,
42,
12 43,
44,
45,
46,
47,
48,
49,
50,
51,-
1,-
1,-
1,-
1,-
1,-
1
13 };
14 public static byte[] FromBase64String(
string inData)
15 {
16 int inDataLength =
inData.Length;
17 int lengthmod4 = inDataLength %
4;
18 int calcLength = (inDataLength -
lengthmod4);
19 byte[] outData =
new byte[inDataLength /
4 *
3 +
3];
20 int j =
0;
21 int i;
22 int num1, num2, num3, num4;
23
24 for (i =
0; i < calcLength; i +=
4, j +=
3)
25 {
26 num1 =
base64Index[inData[i]];
27 num2 = base64Index[inData[i +
1]];
28 num3 = base64Index[inData[i +
2]];
29 num4 = base64Index[inData[i +
3]];
30
31 outData[j] = (
byte)((num1 <<
2) | (num2 >>
4));
32 outData[j +
1] = (
byte)(((num2 <<
4) &
0xf0) | (num3 >>
2));
33 outData[j +
2] = (
byte)(((num3 <<
6) &
0xc0) | (num4 &
0x3f));
34 }
35 i =
calcLength;
36 switch (lengthmod4)
37 {
38 case 3:
39 num1 =
base64Index[inData[i]];
40 num2 = base64Index[inData[i +
1]];
41 num3 = base64Index[inData[i +
2]];
42
43 outData[j] = (
byte)((num1 <<
2) | (num2 >>
4));
44 outData[j +
1] = (
byte)(((num2 <<
4) &
0xf0) | (num3 >>
2));
45 j +=
2;
46 break;
47 case 2:
48 num1 =
base64Index[inData[i]];
49 num2 = base64Index[inData[i +
1]];
50
51 outData[j] = (
byte)((num1 <<
2) | (num2 >>
4));
52 j +=
1;
53 break;
54 }
55 Array.Resize(
ref outData, j);
56 return outData;
57 }
58 public static string ToBase64String(
byte[] inData)
59 {
60 int inDataLength =
inData.Length;
61 int outDataLength = (
int)(inDataLength /
3 *
4) +
4;
62 char[] outData =
new char[outDataLength];
63
64 int lengthmod3 = inDataLength %
3;
65 int calcLength = (inDataLength -
lengthmod3);
66 int j =
0;
67 int i;
68
69 for (i =
0; i < calcLength; i +=
3, j +=
4)
70 {
71 outData[j] = base64Table[inData[i] >>
2];
72 outData[j +
1] = base64Table[((inData[i] &
0x03) <<
4) | (inData[i +
1] >>
4)];
73 outData[j +
2] = base64Table[((inData[i +
1] &
0x0f) <<
2) | (inData[i +
2] >>
6)];
74 outData[j +
3] = base64Table[(inData[i +
2] &
0x3f)];
75 }
76
77 i =
calcLength;
78 switch (lengthmod3)
79 {
80 case 2:
81 outData[j] = base64Table[inData[i] >>
2];
82 outData[j +
1] = base64Table[((inData[i] &
0x03) <<
4) | (inData[i +
1] >>
4)];
83 outData[j +
2] = base64Table[(inData[i +
1] &
0x0f) <<
2];
84 j +=
3;
85 break;
86 case 1:
87 outData[j] = base64Table[inData[i] >>
2];
88 outData[j +
1] = base64Table[(inData[i] &
0x03) <<
4];
89 j +=
2;
90 break;
91 }
92 return new string(outData,
0, j);
93 }
94 public static string Base64Encode(
string source)
95 {
96 byte[] barray =
Encoding.Default.GetBytes(source);
97 return Base64Helper.ToBase64String(barray);
98 }
99 public static string Base64Decode(
string source)
100 {
101 byte[] barray =
Base64Helper.FromBase64String(source);
102 return Encoding.Default.GetString(barray);
103 }
104 }
转载于:https://www.cnblogs.com/softcreator/articles/softcreator_8627573.html
