打卡小程序怎么做_Node.js API详解之 string

阅读  ·  发布日期 2021-01-05 14:38  ·  admin
Node.js API详解之 string_decoder用法实例分析       这篇文章主要介绍了Node.js API详解之 string_decoder用法,结合实例形式分析了Node.js API中string_decoder的功能、用法及操作注意事项,需要的朋友可以参考下

本文实例讲述了Node.js API详解之 string_decoder用法。分享给大家供大家参考,具体如下:

string_decoder 模块提供了一个 API,用于把 Buffer 对象解码成字符串。

对于参数末尾不完整的多字节字符,string_decoder会将其保存在内部的buffer中,当再次解码时,补充到参数开头。

通过 const { StringDecoder } = require(‘string_decoder'); 的方式引用string_decoder模块。

目录:

new StringDecoder([encoding]) stringDecoder.write(buffer) stringDecoder.end([buffer])

创建一个新的StringDecoder实例,可传递encoding参数作为字符编码格式,默认为'utf8′

stringDecoder.write(buffer)

说明:

返回一个解码后的字符串,并确保返回的字符串不包含残缺的多字节字符,残缺的多字节字符会被保存在一个内部的 buffer 中,
用于下次调用 stringDecoder.write() 或 stringDecoder.end()。
buffer:待解码的Buffer

demo:

const decoder = new StringDecoder('utf8');
//字符的16进制小于0x80属于单字节
let outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67]));
console.log(outString);
//xiaoqiang
//字符的16进制大于0x80属于双字节
outString = decoder.write(Buffer.from([0xC2, 0xA2]));
console.log(outString);
//单双字节混合,置于末尾
outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67, 0xC2]));
console.log(outString);
//xiaoqiang
outString = decoder.write(Buffer.from([0xA2]));
console.log(outString);
//单双字节混合,置于中间
outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0xC2, 0x69, 0x61, 0x6e, 0x67]));
console.log(outString);
//xiaoq iang
outString = decoder.write(Buffer.from([0xA2]));
console.log(outString);
//单双字节混合,置于开始
outString = decoder.write(Buffer.from([0xC2, 0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67]));
console.log(outString);
// xiaoqiang
outString = decoder.write(Buffer.from([0xA2]));
console.log(outString);
//单双字节混合,置于末尾
outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67, 0xC2]));
console.log(outString);
//xiaoqiang
outString = decoder.write(Buffer.from([0x78,0xA2]));
console.log(outString);
// x 

stringDecoder.end([buffer])

说明:

以字符串的形式返回内部 buffer 中剩余的字节,残缺的字节会被替换成符合字符编码的字符
如果提供了 buffer 参数,则在返回剩余字节之前会再执行一次 stringDecoder.write()

demo:

const decoder = new StringDecoder('utf8');
//字符的16进制小于0x80属于单字节
let outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67]));
console.log(outString);
//xiaoqiang
outString = decoder.end();
console.log(outString);
//单双字节混合,置于末尾
outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67, 0xC2]));
console.log(outString);
//xiaoqiang
outString = decoder.end(Buffer.from([0xA2]));
console.log(outString);
//单双字节混合,置于末尾
outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67, 0xC2]));
console.log(outString);
//xiaoqiang
outString = decoder.end();
console.log(outString);

希望本文所述对大家node.js程序设计有所帮助。