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我试图制作一个Android应用程序，它显示我的AWS ec2实例上的顶级命令数据。以下是我写的node.js文件。它使用topparser npm模块发送最高命令结果。并且使用checkCpuUsage函数，如果cpu使用率超过1％，它将发送通知。检索node.js中的JSON数据时出错
var express = require('express');
var app = express();
var fs = require('fs');
var spawn = require('child_process').spawn;
var topparser=require("topparser");
var FCM = require('fcm-node');
var server = app.listen(8080);
var regTokens = [];
var bodyParser = require('body-parser');
app.use(bodyParser.json());
let data_builder = "";
const DEFAUT_TOP_DURATION = 2000;
function getTopData(callback, duration) {
duration = duration || DEFAUT_TOP_DURATION;
var top = spawn('top');
top.stdout.on('data', function(data) {
data_builder+=data.toString();
});
setTimeout(function() {
top.kill();
callback(topparser.parse(data_builder,10))
},duration);
}
function sendServerData(req, res) {
getTopData((data)=>{
res.status("200").send(data);
})
}
function checkCpuUsage() {
getTopData((data)=>{
var idl = data.cpu.idle;
if(idl<99) {
sendNotification(idl);
}
}, 2000)
}
function saveRegToken(req, res) {
console.log("saveRegToken req body", req.body)
regTokens.push(req.body.token);
res.send(200);
}
let server_key =JSON.parse(fs.readFileSync(('./config.json'))); ;
function sendNotification(idle){
var idl = idle;
var fcm = new FCM(server_key);
for(i=0; i<regTokens.length; i++) {
var message = {
to: 'regTokens[i]',
notification: {
title: 'CPU Usage!',
body: 'CPU Usage: ' + idl,
},
};
fcm.send(message, function(err, response){
if (err) {
console.log("Something has gone wrong!");
} else {
console.log("Successfully sent with response: ", response);
}
});
}
}
setInterval(()=>checkCpuUsage(),10000);
app.get('/sys', sendServerData);
app.post('/save_token', saveRegToken)
console.log("server listening on 8080");
，我发现了以下错误在checkCpuUsage（）函数：
var idl = data.cpu.idle;
^
TypeError: Cannot read property 'cpu' of undefined
at getTopData (/home/ubuntu/server_monitor/server1.1.1.js:38:17)
at Timeout._onTimeout (/home/ubuntu/server_monitor/server1.1.1.js:26:3)
at ontimeout (timers.js:469:11)
at tryOnTimeout (timers.js:304:5)
at Timer.listOnTimeout (timers.js:264:5)
以下是从topparser模块的示例JSON结果：
{
process:[
{
pid:'1990',
user:'alex',
pr:'20',
ni:'0',
virt:'1560516',
res:'90656',
shr:'21864',
s:'S',
cpu:'6.1',
mem:'12.5',
time:'13:46.58',
command:'cinnamon'
},
{
pid:'5381',
user:'alex',
pr:'20',
ni:'0',
virt:'929508',
res:'119792',
shr:'8132',
s:'S',
cpu:'6.1',
mem:'16.5',
time:'11:14.11',
command:'firefox'
},
{
pid:'0245',
user:'alex',
pr:'20',
ni:'0',
virt:'24948',
res:'1508',
shr:'1056',
s:'R',
cpu:'6.1',
mem:'0.2',
time:'0:00.02',
command:'top'
},
{
pid:'1',
user:'root',
pr:'20',
ni:'0',
virt:'37352',
res:'5688',
shr:'488',
s:'S',
cpu:'0.0',
mem:'0.8',
time:'0:04.93',
command:'init'
},
{
pid:'2',
user:'root',
pr:'20',
ni:'0',
virt:'0',
res:'0',
shr:'0',
s:'S',
cpu:'0.0',
mem:'0.0',
time:'0:00.07',
command:'kthreadd'
},
{
pid:'3',
user:'root',
pr:'20',
ni:'0',
virt:'0',
res:'0',
shr:'0',
s:'S',
cpu:'0.0',
mem:'0.0',
time:'0:54.23',
command:'ksoftirqd/0'
},
{
pid:'4',
user:'root',
pr:'20',
ni:'0',
virt:'0',
res:'0',
shr:'0',
s:'S',
cpu:'0.0',
mem:'0.0',
time:'0:00.00',
command:'kworker/0:0'
}
],
task:{
total:194,
running:1,
sleeping:193,
stopped:0,
zombie:0
},
cpu:{
user:0.9,
system:3.1,
ni:0.1,
'idle':95,
wa:0.3,
hi:0.6,
si:0,
st:0
},
ram:{
total:727308,
used:664028,
free:63280,
buffers:7600
},
swap:{
total:753660,
used:309516,
free:444144,
cachedMem:187424
}
}