Js binary data operations method, js binary operations

Js binary data operations method, js binary operations

Recently, I have made several projects to use js to operate binary data and transmit it through socket and the background. Use a blog here to make a record

First, create a new socket:

var socket=new WebSocket("ws://192.168.0.147");

Then define the function to be executed after the socket is opened and connected:

Websocket has a binaryType attribute, which can be set to "blob" or "arraybuffer". The default format is "blob". When creating a project, you forget to set it to "arraybuffer, when receiving the data below, you need to use the Blob Object to pick it up.

Socket. onopen = function () {// send the logon frame. The 4-20 bits indicate the mobile phone number var loginArr = [0X02,0X02,0X00, 0X1E, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0X20, 0 X, 0 X x, 0 X, 0 X, 0X00, 0X0D, 0X0A]}

The following code is forwarded to bype:

Var loginBuffer = new ArrayBuffer (30); var loginDataview = new DataView (loginBuffer); // localstorageuserinfo indicates the user's mobile phone number cached locally. var telArr = localstorageuserinfo. telPhone; var loginTime = tempTrans (); for (var I = 0; I <loginArr. length;) {loginDataview. setInt8 (I, loginArr [I]); if (I> 3 & I <(telArr. length + 4) {loginDataview. setInt8 (I, telArr. charCodeAt (I-4);} if (I> 19 & I <loginArr. length-2) {loginDataview. setInt8 (I, loginTime [I- 20]);} I ++;} // login package socket. send (loginDataview. buffer); // The formatting time is sorted by two-digit year, month, day, minute, second, and one-digit by the end. function tempTrans (time) {if (! Time) {time = new Date ();} var u32Dataview = new DataView (new Uint16Array ([time. getFullYear ()]). buffer); var uint8 = []; uint8.push (new DataView (new Uint8Array ([0X00]). buffer ). getUint8 (0) for (var I = u32Dataview. byteLength-1; I> = 0; I --) {uint8.push (u32Dataview. getUint8 (I)} uint8.push (new DataView (new Uint8Array ([time. getMonth () + 1]). buffer ). getUint8 (0); uint8.push (new DataView (new Uint8Array ([time. getDate ()]). buffer ). getUint8 (0); uint8.push (new DataView (new Uint8Array ([time. getHours ()]). buffer ). getUint8 (0); uint8.push (new DataView (new Uint8Array ([time. getMinutes ()]). buffer ). getUint8 (0); uint8.push (new DataView (new Uint8Array ([time. getSeconds ()]). buffer ). getUint8 (0); return uint8 ;}

The process of sending is probably like this, first new ArrayBuffer object, the object needs to fill in the buffer length parameters, specific view api => https://msdn.microsoft.com/zh-cn/library/br212474 (v = vs.94). aspx,

Create a new DataView object and upload ArrayBuffer. Then use the setUint and getUint methods of DataView to read the settings by bit. For details, refer to api => https://msdn.microsoft.com/zh-cn/library/br212463 (v = vs.94). aspx

The following describes how to receive data processing:

// Receives the message onmessagesocket. onmessage = function (data) {var blob _ = new Blob ([data. data]); parseBlob (blob _);} // use fileReader to operate blob Object var reader = {readAs: function (type, blob, cb) {var r = new FileReader (); r. onloadend = function () {if (typeof (cb) = 'function') {cb. call (r, r. result) ;}} try {r ['readas' + type] (blob) ;}catch (e) {}} function parseBlob (blob) {reader. readAs ('arraybuffer', blob. slice (0, blob. size), function (arr) {var dataview _ = new DataView (arr); // the second digit in the Protocol is the var socketConType = dataview _. getUint8 (1); // convert it to a string to read data var modulelength = (dataview _. buffer. byteLength-46)/33; var modulestate ={}; reader. readAs ('text', blob. slice (I * 33 + 37, I * 33 + 37 + 32), function (result) {modulestate [dataview _. getUint8 (I * 33 + 36)] = result ;});})}

You can do whatever you want after converting it into a string.

The above is the method used to operate binary data when I am working on the project. The bitwise read headers will be blown up... after google's open-source protobuf is able to set the data format, all read operations do not need to be spliced by themselves, which is very comfortable. However, I don't know the background technology. I can only eat the scum TnT behind the background bosses.

This js method for operating binary data is all the content that I have shared with you. I hope to give you a reference and support for the help house.