~~~ const mongoose = require('mongoose'); const db ="mongodb://localhost/douban" mongoose.Promise = global.Promise; exports.connect =()=>{ let maxConnectTimes = 0; return new Promise((resolve,reject)=>{ if(process.env.NODE_ENV!=='production'){ mongoose.set('debug',true) } mongoose.connect(db,{useNewUrlParser: true}); mongoose.connection.on('disconnected',()=>{ maxConnectTimes++; if(maxConnectTimes<5){ mongoose.connect(db); }else{ throw new Error('数据库挂了吧') } }) mongoose.connection.on('error',err=>{ reject(err); }) mongoose.connection.on('open',()=>{ const Dog = mongoose.model('Dog',{name:String}) const doga= new Dog({name:"dogo"}) doga.save().then(()=>{ console.log('wang') }) console.log('MongdoDB Connect successfully') }) }) } ~~~