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這篇文章主要為大家展示了Node.js API中怎么使用string_decoder,內(nèi)容簡而易懂,希望大家可以學(xué)習(xí)一下,學(xué)習(xí)完之后肯定會有收獲的,下面讓小編帶大家一起來看看吧。
string_decoder 模塊提供了一個 API,用于把 Buffer 對象解碼成字符串。
對于參數(shù)末尾不完整的多字節(jié)字符,string_decoder會將其保存在內(nèi)部的buffer中,當(dāng)再次解碼時,補充到參數(shù)開頭。
通過 const { StringDecoder } = require(‘string_decoder'); 的方式引用string_decoder模塊。
目錄:
new StringDecoder([encoding])
說明:
創(chuàng)建一個新的StringDecoder實例,可傳遞encoding參數(shù)作為字符編碼格式,默認(rèn)為'utf8′
stringDecoder.write(buffer)
說明:
返回一個解碼后的字符串,并確保返回的字符串不包含殘缺的多字節(jié)字符,殘缺的多字節(jié)字符會被保存在一個內(nèi)部的 buffer 中,
用于下次調(diào)用 stringDecoder.write() 或 stringDecoder.end()。
buffer:待解碼的Buffer
demo:
const decoder = new StringDecoder('utf8'); //字符的16進制小于0x80屬于單字節(jié) let outString = decoder.write(Buffer.from([0x78, 0x69, 0x61, 0x6f, 0x71, 0x69, 0x61, 0x6e, 0x67])); console.log(outString); //xiaoqiang //字符的16進制大于0x80屬于雙字節(jié) outString = decoder.write(Buffer.from([0xC2, 0xA2])); console.log(outString); //¢ //單雙字節(jié)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); //¢ //單雙字節(jié)混合,置于中間 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); //? //單雙字節(jié)混合,置于開始 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); //? //單雙字節(jié)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])
說明:
以字符串的形式返回內(nèi)部 buffer 中剩余的字節(jié),殘缺的字節(jié)會被替換成符合字符編碼的字符
如果提供了 buffer 參數(shù),則在返回剩余字節(jié)之前會再執(zhí)行一次 stringDecoder.write()
demo:
const decoder = new StringDecoder('utf8'); //字符的16進制小于0x80屬于單字節(jié) 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); // //單雙字節(jié)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); //¢ //單雙字節(jié)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);
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