coap模塊中json的示例代碼缺少了.setHeader("Accept","application/json")，添加后即可正常運(yùn)行

結(jié)合注釋理解代碼

const coap = require('coap') // or coap
    , bl   = require('bl')

//創(chuàng)建服務(wù)器
coap.createServer(function(req, res) {
  if (req.headers['Accept'] != 'application/json') {
    res.code = '4.06'
    return res.end()
  }
  //得到請(qǐng)求數(shù)據(jù)并解析
  var data = req.url.split('/')
  console.log(data[1] + ':' + data[2] + '\n')
  //設(shè)置響應(yīng)的格式為json
  res.setOption('Content-Format', 'application/json')
  //發(fā)送響應(yīng)
  res.end(JSON.stringify({ cmd: "shutdown" }))

}).listen(function() {

//啟動(dòng)監(jiān)聽(tīng)服務(wù)后創(chuàng)建請(qǐng)求
  coap
    .request({
      pathname: '/temperature/32',//請(qǐng)求內(nèi)容
      options: {
      }
    })
    .setHeader("Accept","application/json")//設(shè)置請(qǐng)求頭為json
    .on('response', function(res) {

      //打印響應(yīng)代號(hào)
      console.log('response code', res.code)
      if (res.code !== '2.05')
        return process.exit(1)

      res.pipe(bl(function(err, data) {
        //json解碼，輸出響應(yīng)cmd字段對(duì)應(yīng)的值
        var json = JSON.parse(data)
        console.log(json.cmd)
        process.exit(0)
      }))
    })
    .end()
})

測(cè)試

$ node son
->temperature:32

    response code 2.05
    shutdown