3-3、node的一些实例

1、新建一个get

var express=require('express');
var app =express();

//设置跨域访问
app.all('*', function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "X-Requested-With");
  res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
  res.header("X-Powered-By",' 3.2.1');
  res.header("Content-Type", "application/json;charset=utf-8");
  next();
});

var questions=[
  {
    data:213,
    num:444,
    age:12
  },
  {
    data:456,
    num:678,
    age:13
  }];

//写个接口123
app.get('/api/getGps',function(req,res){
  res.status(200),
    res.json(questions)
});

//配置服务端口 
var server = app.listen(3000, function () {
  var host = server.address().address;
  var port = server.address().port;
  console.log('Example app listening at http://%s:%s', host, port);
})
// 前端
$.getJSON('http://127.0.0.1:3000/api/getGps', function(data) {}

2、循环读取文件夹的图片发送给前端

var fs = require('fs')
var app = require('express')();
var webSocket = require('ws')
var wss = new webSocket.Server({port:8080})

var urls = '/Users/yangyangran/Downloads/图片收藏'

var images = fs.readdirSync(urls)

images.forEach(function (item, index) {
    console.log(item)
})

var index = 0;
var len = images.length;
wss.on('connection', function connection(ws) {

    setInterval(()=>{
        fs.readFile(`${urls}/${images[index]}`, 'binary',function (err, data) {
            if (err) {
                return console.error(err);
            }
            console.log("异步读取: " );
            ws.send(data)
            index = (index + 1)%len;
            // const buf = Buffer.from(data, 'binary');
            // console.log(buf.toString('base64'));
            // ws.send(buf.toString('base64'));
        });
    }, 500)
})
app.listen(3000);
// 前端
    var ws = new WebSocket('ws://localhost:8080');
    ws.onopen = function () {
        console.log('ws onopen');
    };
    ws.onmessage = function (e) {
        var url = "data:image/png;base64," + window.btoa(e.data);
        $('#show').html(`<img src=${url} alt="img">`)
    };

3、按行读取并存入

var fs = require('fs')
var readline = require('readline')

function readFileToArr(fReadName,callback){
  var fRead = fs.createReadStream(fReadName);
  var objReadline = readline.createInterface({
    input:fRead
  });
  var arr = new Array();
  objReadline.on('line',function (line) {
    arr.push(line);
    //console.log('line:'+ line);
  });
  objReadline.on('close',function () {
    // console.log(arr);
    callback(arr);
  });
}

var gpsData = []

readFileToArr('/Users/yangyangran/Desktop/cve/1575026840.8389428-c1_gps.txt', data=>{
  data.forEach(x=>{
    if(x.indexOf('$GNRMC') > -1 || x.indexOf('$GPRMC') > -1){
      let fields = x.split(',')
      let lat = fields[3].slice(0,2)-0 + fields[3].slice(2)/60
      let lon = fields[5].slice(0,3)-0 + fields[5].slice(3)/60
      if(fields[3] && fields[5]){
        gpsData.push([lon, lat])
      }
    }
  })
})