1 var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
2 var base64DecodeChars = new Array(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 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, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);
3 /**
4 * base64编码
5 * @param {Object} str
6 */
7 function base64encode(str){
8 var out, i, len;
9 var c1, c2, c3;
10 len = str.length;
11 i = 0;
12 out = "";
13 while (i < len) {
14 c1 = str.charCodeAt(i++) & 0xff;
15 if (i == len) {
16 out += base64EncodeChars.charAt(c1 >> 2);
17 out += base64EncodeChars.charAt((c1 & 0x3) << 4);
18 out += "==";
19 break;
20 }
21 c2 = str.charCodeAt(i++);
22 if (i == len) {
23 out += base64EncodeChars.charAt(c1 >> 2);
24 out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
25 out += base64EncodeChars.charAt((c2 & 0xF) << 2);
26 out += "=";
27 break;
28 }
29 c3 = str.charCodeAt(i++);
30 out += base64EncodeChars.charAt(c1 >> 2);
31 out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
32 out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
33 out += base64EncodeChars.charAt(c3 & 0x3F);
34 }
35 return out;
36 }
37 /**
38 * base64解码
39 * @param {Object} str
40 */
41 function base64decode(str){
42 var c1, c2, c3, c4;
43 var i, len, out;
44 len = str.length;
45 i = 0;
46 out = "";
47 while (i < len) {
48 /* c1 */
49 do {
50 c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
51 }
52 while (i < len && c1 == -1);
53 if (c1 == -1)
54 break;
55 /* c2 */
56 do {
57 c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
58 }
59 while (i < len && c2 == -1);
60 if (c2 == -1)
61 break;
62 out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
63 /* c3 */
64 do {
65 c3 = str.charCodeAt(i++) & 0xff;
66 if (c3 == 61)
67 return out;
68 c3 = base64DecodeChars[c3];
69 }
70 while (i < len && c3 == -1);
71 if (c3 == -1)
72 break;
73 out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
74 /* c4 */
75 do {
76 c4 = str.charCodeAt(i++) & 0xff;
77 if (c4 == 61)
78 return out;
79 c4 = base64DecodeChars[c4];
80 }
81 while (i < len && c4 == -1);
82 if (c4 == -1)
83 break;
84 out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
85 }
86 return out;
87 }
88 /**
89 * utf16转utf8
90 * @param {Object} str
91 */
92 function utf16to8(str){
93 var out, i, len, c;
94 out = "";
95 len = str.length;
96 for (i = 0; i < len; i++) {
97 c = str.charCodeAt(i);
98 if ((c >= 0x0001) && (c <= 0x007F)) {
99 out += str.charAt(i);
100 }
101 else
102 if (c > 0x07FF) {
103 out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
104 out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
105 out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
106 }
107 else {
108 out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
109 out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
110 }
111 }
112 return out;
113 }
114 /**
115 * utf8转utf16
116 * @param {Object} str
117 */
118 function utf8to16(str){
119 var out, i, len, c;
120 var char2, char3;
121 out = "";
122 len = str.length;
123 i = 0;
124 while (i < len) {
125 c = str.charCodeAt(i++);
126 switch (c >> 4) {
127 case 0:
128 case 1:
129 case 2:
130 case 3:
131 case 4:
132 case 5:
133 case 6:
134 case 7:
135 // 0xxxxxxx
136 out += str.charAt(i - 1);
137 break;
138 case 12:
139 case 13:
140 // 110x xxxx 10xx xxxx
141 char2 = str.charCodeAt(i++);
142 out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
143 break;
144 case 14:
145 // 1110 xxxx10xx xxxx10xx xxxx
146 char2 = str.charCodeAt(i++);
147 char3 = str.charCodeAt(i++);
148 out += String.fromCharCode(((c & 0x0F) << 12) | ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));
149 break;
150 }
151 }
152 return out;
153 }
154 //demo
155 //function doit(){
156 // var f = document.f;
157 // f.output.value = base64encode(utf16to8(f.source.value));
158 // f.decode.value = utf8to16(base64decode(f.output.value));
159 //}
