字符串、utf-8字节数组、base64编码的互相转化

最新推荐文章于 2025-09-10 23:44:22 发布

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本文通过一个实例，演示了如何将字符串转换为UTF-8字节，再进一步转化为Base64编码，以及如何逆向操作，从Base64还原到原始字符串。代码中详细展示了strToUtf8、utf8ToBase64、base64ToUtf8和utf8ToStr四个关键函数的实现过程。

话不多说，直接上代码。。。

<!doctype html>
<html lang="en">
 <head>
  <meta charset="UTF-8">
  <meta name="Generator" content="EditPlus®">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <title>编码转化</title>
 </head>
 <body>
  
 </body>
 <script>
 	window.onload = function () {
		var text = '这是一段文本, http://www.www.com?a=b&c=文本, <div></div>'
		console.log('用来测试转化的原始文本', text)
		var utf8Bytes = strToUtf8(text)
		console.log('String转UTF-8', utf8Bytes)
		
		var base64Str = utf8ToBase64(utf8Bytes)
		console.log('UTF-8转base64', base64Str)
		
		var base64ToUtf8Bytes = base64ToUtf8(base64Str)
		console.log('base64转UTF-8字节数组', base64ToUtf8Bytes)

		var utf8ToString = utf8ToStr(base64ToUtf8Bytes)
		console.log('UTF-8字节数组转为String', utf8ToString)

		console.log('转换前后是否相等', text === utf8ToString)
	}
	
	// String转为utf-8字节数组
	function strToUtf8 (str) {
		// URL转码
		const code = encodeURIComponent(str)
		const bytes = []
		for (var i = 0; i < code.length; i++) {
			const c = code.charAt(i)
			if (c === '%') {
				const hex = code.charAt(i + 1) + code.charAt(i + 2)
				const hexVal = parseInt(hex, 16)
				bytes.push(hexVal)
				i += 2
			} else bytes.push(c.charCodeAt(0))
		}
		return bytes
	}

	// utf-8转为base64编码
	function utf8ToBase64 (utf8Bytes) {
		// 对字符串进行编码
		var encode = encodeURI(utf8Bytes)
		// 对编码的字符串转化base64
		var base64 = btoa(encode)
		return base64
	}

	// base64编码转为utf-8
	function base64ToUtf8 (base64) {
		// 对base64转编码
		var decode = atob(base64)
		// 编码转字符串
		var str = decodeURI(decode)
		// 字符串转为utf-8字节数组
		var utf8Arr = str.split(',')
		for (var i = 0; i < utf8Arr.length; i++) {
			utf8Arr[i] = utf8Arr[i] - 0
		}
		return utf8Arr
	}

	// utf-8字节数组转为String
	function utf8ToStr (utf8) {
		var encoded = ""
		var strtr = ""
		for (var i = 0; i < utf8.length; i++) {
			encoded += '%' + utf8[i].toString(16)
		}
		str = decodeURIComponent(encoded)
		return str
	}
 </script>
</html>