log4js简单使用
npm install log4js
var log4js = require("log4js");
var logger = log4js.getLogger();
logger.level = "debug"; // default level is OFF - which means no logs at all.
logger.debug("Some debug messages");
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附加器
Appender 将日志事件序列化为某种形式的输出。他们可以写入文件、发送电子邮件、通过网络发送数据。所有的 appender 都有一个type决定使用哪个 appender。例如：
const log4js = require('log4js')
log4js.configure({
appenders: {
out: { type: 'stdout' },
app: { type: 'file', filename: 'application.log' },
},
categories: {
default: { appenders: ['out', 'app'], level: 'debug' },
},
})
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这定义了两个名为“out”和“app”的附加程序。‘out’ 使用写入标准输出的标准输出附加程序。‘app’ 使用文件appender，配置为写入 ‘application.log’。
我的配置
const log4js = require('log4js')
log4js.configure({
appenders: {
tiktok: {
type: 'log',
},
},
categories: { default: { appenders: ['tiktok'], level: 'all' } },
pm2: true,
pm2InstanceVar: 'NODE_APP_INSTANCE',
})
const log = log4js.getLogger('日志')
log.debug('系统', os.platform())
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log.js
const express = require('express')
const app = express()
const expressWs = require('express-ws')(app)
let LogWS = null
const rooms = []
app.ws('/log/', (ws, req) => {
LogWS = ws
const { id } = req.query
let curr = rooms.find(room => room.id == id)
if (!curr) {
curr = { id, ws }
rooms.push(curr)
}
else {
curr.ws = ws
}
console.log(rooms)
})
app.listen('9001', async() => {
console.log('日志服务已启动9001端口')
})
function stdoutAppender(layout, timezoneOffset) {
const appender = (loggingEvent) => {
if (loggingEvent.level.levelStr == 'DEBUG') {
const currWs = rooms.find(room => room.id == loggingEvent.data[0])
if (currWs && LogWS)
LogWS.send(`${layout(loggingEvent, timezoneOffset)}\n`)
}
// process.stdout.write(`${layout(loggingEvent, timezoneOffset)}\n`);
process.stdout.write(`${JSON.stringify(loggingEvent)}\n`)
}
// add a shutdown function.
appender.shutdown = (done) => {
process.stdout.write('', done)
}
return appender
}
// stdout configure doesn't need to use findAppender, or levels
function configure(config, layouts) {
// the default layout for the appender
let layout = layouts.colouredLayout
// check if there is another layout specified
if (config.layout) {
// load the layout
layout = layouts.layout(config.layout.type, config.layout)
}
// create a new appender instance
return stdoutAppender(layout, config.timezoneOffset)
}
// export the only function needed
exports.configure = configure
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疑问
appender似乎只支持路径和模块名，不支持直接写入函数。 如果可以支持写入函数就更好了，有更大的灵活性。或许有更好的方式。