将源文件的字符串传化为二进制数据
- 字符串单位是
byte，二进制位单位bit - 1byte = 8bit
base64 是将二进制数据分割为 6bit 代表一个字符串的格式
-
asda二进制为11000011 11001111 00100110 0001。 8位代表一个字符串 -
base64将二进制数据分割为110000 111100 111100 100110 0001。
根据对应关系表转化
代码实现
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8"/>
<title>Document</title>
</head>
<body>
<script>
var base64Obj = {
0: 'A', 1: 'B', 2: 'C', 3: 'D', 4: 'E', 5: 'F',6: 'G',7: 'H', 8: 'I', 9: 'J',
10: 'K', 11: 'L', 12: 'M', 13: 'N', 14: 'O', 15: 'P', 16: 'Q', 17: 'R', 18: 'S', 19: 'T',
20: 'U', 21: 'V', 22: 'W', 23: 'X', 24: 'Y', 25: 'Z', 26: 'a', 27: 'b', 28: 'c', 29: 'd',
30: 'e', 31: 'f', 32: 'g',33: 'h', 34: 'i', 35: 'j', 36: 'k', 37: 'l', 38: 'm', 39: 'n',
40: 'o', 41: 'p', 42: 'q', 43: 'r', 44: 's', 45: 't', 46: 'u', 47: 'v', 48: 'w', 49: 'x',
50: 'y', 51: 'z', 52: '0', 53: '1', 54: '2',55: '3',56: '4', 57: '5',58: '6', 59: '7',
60: '8',61: '9', 62: '+', 63: '/'
}
// 转二进制
function strToBinary(str){
var result = [];
for (var i = 0; i < str.length; i++ ) {
var tem = str[i].charCodeAt().toString(2)
while (tem.length < 8) {
tem = '0' + tem
}
result.push(tem)
}
return result.join("");
}
console.log(strToBinary('ABC'))
// 二进制格式切割成6位一组的
function toSixbit (str) {
if (str.length < 6) {
return str
}
var resultArr = []
while (str.length >= 6) {
resultArr.push(str.slice(0, 6))
str = str.slice(6)
}
return resultArr
}
// 6位的转base64
function toBase64 (arr) {
for (var j = 0; j < arr.length; j++) {
var key = parseInt(arr[j], 2)
arr[j] = base64Obj[key]
}
return arr.join('')
}
console.log(toSixbit(strToBinary('ABC')))
console.log('ABC 转base64为' + toBase64(toSixbit(strToBinary('ABC'))))
</script>
</body>
</html>
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