JavaScript前端开发之实现二进制读写操作

!function (entrance) {  "use strict";  if ("object" === typeof exports && "undefined" !== typeof module) {    module.exports = entrance();  } else if ("function" === typeof define && define.amd) {    define([], entrance());  } else {    var f;    if ("undefined" !== typeof window) {      f = window;    } else {      throw new Error('wrong execution environment');    }    f.TinyStream = entrance();  }}(function () {  var binaryPot = {    /**     * 初始化字节流,把-128至128的区间改为0-256的区间.便于计算     * @param {Array} array 字节流数组     * @return {Array} 转化好的字节流数组     */    init: function (array) {      for (var i = 0; i < array.length; i++) {        array[i] *= 1;        if (array[i] < 0) {          array[i] += 256        }        if(array[i]>255){          throw new Error('不合法字节流')        }      }      return array;    },    /**     * 把一段字符串按照utf8编码写到缓冲区中     * @param {String} str 将要写入缓冲区的字符串     * @param {Boolean} isGetBytes 是否只得到内容字节(不包括最开始的两位占位字节)     * @returns {Array} 字节流     */    writeUTF: function (str, isGetBytes) {      var back = [],        byteSize = 0;      for (var i = 0; i < str.length; i++) {        var code = str.charCodeAt(i);        if (code >= 0 && code <= 127) {          byteSize += 1;          back.push(code);        } else if (code >= 128 && code <= 2047) {          byteSize += 2;          back.push((192 | (31 & (code >> 6))));          back.push((128 | (63 & code)))        } else if (code >= 2048 && code <= 65535) {          byteSize += 3;          back.push((224 | (15 & (code >> 12))));          back.push((128 | (63 & (code >> 6))));          back.push((128 | (63 & code)))        }      }      for (i = 0; i < back.length; i++) {        if (back[i] > 255) {          back[i] &= 255        }      }      if (isGetBytes) {        return back      }      if (byteSize <= 255) {        return [0, byteSize].concat(back);      } else {        return [byteSize >> 8, byteSize & 255].concat(back);      }    },    /**     * 把一串字节流按照utf8编码读取出来     * @param arr 字节流     * @returns {String} 读取出来的字符串     */    readUTF: function (arr) {      if (Object.prototype.toString.call(arr) == "[object String]") {        return arr;      }      var UTF = "",        _arr = this.init(arr);      for (var i = 0; i < _arr.length; i++) {        var one = _arr[i].toString(2),          v = one.match(/^1+?(?=0)/);        if (v && one.length == 8) {          var bytesLength = v[0].length,            store = _arr[i].toString(2).slice(7 - bytesLength);          for (var st = 1; st < bytesLength; st++) {            store += _arr[st + i].toString(2).slice(2)          }          UTF += String.fromCharCode(parseInt(store, 2));          i += bytesLength - 1        } else {          UTF += String.fromCharCode(_arr[i])        }      }      return UTF    },    /**     * 转换成Stream对象     * @param x     * @returns {Stream}     */    convertStream: function (x) {      if (x instanceof Stream) {        return x      } else {        return new Stream(x)      }    },    /**     * 把一段字符串转为mqtt格式     * @param str     * @returns {*|Array}     */    toMQttString: function (str) {      return this.writeUTF(str)    }  };  /**   * 读取指定长度的字节流到指定数组中   * @param {Stream} m Stream实例   * @param {number} i 读取的长度   * @param {Array} a 存入的数组   * @returns {Array} 存入的数组   */  function baseRead(m, i, a) {    var t = a ? a : [];    for (var start = 0; start < i; start++) {      t[start] = m.pool[m.position++]    }    return t  }  /**   * 判断浏览器是否支持ArrayBuffer   */  var supportArrayBuffer = (function () {    return !!window.ArrayBuffer;  })();  /**   * 字节流处理实体类   * @param {String|Array} array 初始化字节流,如果是字符串则按照UTF8的格式写入缓冲区   * @constructor   */  function Stream(array) {    if (!(this instanceof Stream)) {      return new Stream(array);    }    /**     * 字节流缓冲区     * @type {Array}     */    this.pool = [];    if (Object.prototype.toString.call(array) === '[object Array]') {      this.pool = binaryPot.init(array);    } else if (Object.prototype.toString.call(array) == "[object ArrayBuffer]") {      var arr = new Int8Array(array);      this.pool = binaryPot.init([].slice.call(arr));    } else if (typeof array === 'string') {      this.pool = binaryPot.writeUTF(array);    }    var self = this;    //当前流执行的起始位置    this.position = 0;    //当前流写入的多少字节    this.writen = 0;    //返回当前流执行的起始位置是否已经大于整个流的长度    this.check = function () {      return self.position >= self.pool.length    };  }  /**   * 强制转换为Stream对象   * @param x   * @returns {*|Stream}   */  Stream.parse = function (x) {    return binaryPot.convertStream(x);  };  Stream.prototype = {    /**     * 从缓冲区读取4个字节的长度并转换为int值,position往后移4位     * @returns {Number} 读取到的数字     * @description 如果position大于等于缓冲区的长度则返回-1     */    readInt: function () {      if (this.check()) {        return -1      }      var end = "";      for (var i = 0; i < 4; i++) {        end += this.pool[this.position++].toString(16)      }      return parseInt(end, 16);    },    /**     * 从缓冲区读取1个字节,position往后移1位     * @returns {Number}     * @description 如果position大于等于缓冲区的长度则返回-1     */    readByte: function () {      if (this.check()) {        return -1      }      var val = this.pool[this.position++];      if (val > 255) {        val &= 255;      }      return val;    },    /**     * 从缓冲区读取1个字节,或读取指定长度的字节到传入的数组中,position往后移1或bytesArray.length位     * @param {Array|undefined} bytesArray     * @returns {Array|Number}     */    read: function (bytesArray) {      if (this.check()) {        return -1      }      if (bytesArray) {        return baseRead(this, bytesArray.length | 0, bytesArray)      } else {        return this.readByte();      }    },    /**     * 从缓冲区的position位置按UTF8的格式读取字符串,position往后移指定的长度     * @returns {String} 读取的字符串     */    readUTF: function () {      var big = (this.readByte() << 8) | this.readByte();      return binaryPot.readUTF(this.pool.slice(this.position, this.position += big));    },    /**     * 把字节流写入缓冲区,writen往后移指定的位     * @param {Number|Array} _byte 写入缓冲区的字节(流)     * @returns {Array} 写入的字节流     */    write: function (_byte) {      var b = _byte;      if (Object.prototype.toString.call(b).toLowerCase() == "[object array]") {        [].push.apply(this.pool, b);        this.writen += b.length;      } else {        if (+b == b) {          if (b > 255) {            b &= 255;          }          this.pool.push(b);          this.writen++        }      }      return b    },    /**     * 把参数当成char类型写入缓冲区,writen往后移2位     * @param {Number} v 写入缓冲区的字节     */    writeChar: function (v) {      if (+v != v) {        throw new Error("writeChar:arguments type is error")      }      this.write((v >> 8) & 255);      this.write(v & 255);      this.writen += 2    },    /**     * 把字符串按照UTF8的格式写入缓冲区,writen往后移指定的位     * @param {String} str 字符串     * @return {Array} 缓冲区     */    writeUTF: function (str) {      var val = binaryPot.writeUTF(str);      [].push.apply(this.pool, val);      this.writen += val.length;    },    /**     * 把缓冲区字节流的格式从0至256的区间改为-128至128的区间     * @returns {Array} 转换后的字节流     */    toComplements: function () {      var _tPool = this.pool;      for (var i = 0; i < _tPool.length; i++) {        if (_tPool[i] > 128) {          _tPool[i] -= 256        }      }      return _tPool    },    /**     * 获取整个缓冲区的字节     * @param {Boolean} isCom 是否转换字节流区间     * @returns {Array} 转换后的缓冲区     */    getBytesArray: function (isCom) {      if (isCom) {        return this.toComplements()      }      return this.pool    },    /**     * 把缓冲区的字节流转换为ArrayBuffer     * @returns {ArrayBuffer}     * @throw {Error} 不支持ArrayBuffer     */    toArrayBuffer: function () {      if (supportArrayBuffer) {        return new ArrayBuffer(this.getBytesArray());      } else {        throw new Error('not support arraybuffer');      }    },    clear: function () {      this.pool = [];      this.writen = this.position = 0;    }  };  return Stream;});

<script src="binary.js"></script><script>   var ts = TinyStream('我叫张亚涛');   ts.writeUTF('你好');   console.log('获取缓冲区字节流:',ts.getBytesArray());   console.log('当前的缓冲区position为:',ts.position,'writen为:',ts.writen);   console.log('读取第一个utf8字节流:',ts.readUTF());   console.log('当前的缓冲区position为:',ts.position,'writen为:',ts.writen);   console.log('读取第二个utf8字节流:',ts.readUTF());   console.log('当前的缓冲区position为:',ts.position,'writen为:',ts.writen);</script>