以指定编码对字符串进行截取

时间:2022-06-14
本文章向大家介绍以指定编码对字符串进行截取,主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项,具有一定的参考价值,需要的朋友可以参考一下。

假设有字符串“朱元璋”,截取限定的长度为7字节

截取编码为utf-8    结果为“朱”

截取编码为gb2312时  结果为“朱”

字符串为“hello朱元璋”,截取限定的长度为13字节

截取编码为utf-8    结果为“hello朱元”

这里的问题就是gbk编码占位2个字节,而utf-8占位3个字节,完整的示例代码:

1:     2: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">   3: <html>   4:  <head>   5:   <title> new document </title>   6:   <meta name="generator" content="editplus" />   7:   <meta name="author" content="" />   8:   <meta name="keywords" content="" />   9:   <meta name="description" content="" />  10:   <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  11:  </head>  12:    13:  <body>  14:   <script type="text/javascript">  15: function getRealLen(str, isUTF8) {  16:     if (typeof str != 'string') {  17:         return 0;  18:     }  19:       20:     if (!isUTF8) {  21:         return str.replace(/[^x00-xFF]/g, 'xx').length;  22:     } else {  23:         var tempStr = str.replace(/[x00-xFF]/g, '');  24:         return (str.length - tempStr.length) + Math.floor(encodeURI(tempStr).length / 3);  25:     }  26: }  27:    28: function uniLeft(str, isUTF8, len, suffix) {  29:     var str = str.toString();  30:     var len = len * 1;  31:     var suffix = suffix || "";  32:    33:     if (isNaN(len)) {  34:         return str;  35:     }  36:    37:     var uniLen = getRealLen(str, isUTF8),tempStr = '';  38:       39:     if (uniLen <= len) {  40:         return str.substr(0);  41:     }  42:       43:     for (var i = Math.floor(len / 2); i< uniLen; i++) {  44:         tempStr = str.substr(0, i);  45:    46:         if (getRealLen(tempStr, isUTF8) >= len || getRealLen(str.substr(0, i+1), isUTF8) > len) {  47:             return tempStr;  48:         }  49:     }  50: }  51:    52: var str_1 = '朱元璋';  53: var str_2 = 'hello朱元璋';  54:    55: document.write( uniLeft(str_1, false, 3) + "<br/>");//gb2312  56: document.write( uniLeft(str_2, true, 13) );//utf-8  57: </script>  58:  </body>  59: </html>

这里从len/2开始试着截取字符串,截取后调用getRealLen方法获取真实长度,判断是否超出限定的长度