nodejs、express、MongoDB，接口响应时间在1200毫秒左右

Question

使用nodejs、express和MongoDB做了一套服务，但是接口的响应时间很长，1200毫秒左右
测试去掉查询数据库，发现响应时间缩减为200毫秒左右
以下是我的代码，求教

var express = require("express");
var fs = require('fs');
var path = require('path');
var crypto = require('crypto'); //加载加密文件
var redis = require('redis');   // Redis缓存数据库
var router = express.Router();
var MongoClient = require('mongodb').MongoClient;
var ObjectID = require('mongodb').ObjectID;
var url = "mongodb://localhost:27017/books";
// 缓存区
var buf = new Buffer.alloc(2048);
var client = redis.createClient(6379, 'localhost', {});

// 密码加盐加密
function encrypt(pw){
    var key = Math.random().toString().substring(2);
    pw = pw + key;
    var md5 = crypto.createHash('md5');
    var r = md5.update(pw).digest('hex');
    return {key: key, pw: r}
}

client.on('ready', function(err){
    if(err) throw err
    console.log('redis ready')
});

// app端注册
router.post('/enroll', function(req, res){
    var data = {
        userName: req.body.userName,
        sex: req.body.sex,
        userPhone: req.body.userPhone,
        userEmail: req.body.userEmail,
        password: req.body.password,
        status: 1
    }
    for(var k in data){
        if(!data[k]){
            res.json({code:4, content:"参数异常"});
            return false
        }
    }
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err) throw err;
        var dbo = db.db("books");
        dbo.collection("user").find({userPhone: data.userPhone}).count(function(err, num){
            if(err) throw err;
            if(num == 0){
                // 密码加密
                var pwObj = encrypt(data.password);
                data.password = pwObj.pw;
                data.key = pwObj.key;
                dbo.collection("user").insertOne(data, function(err, result) {
                    if (err){
                        res.json({code:4, content: "服务器异常"});
                        throw err;
                    }
                    res.json({code:1, content: "添加成功"});
                })
            }else{
                res.json({code:2, content: "此手机号码已注册"})
            }
            db.close();
        });
    });
});

// APP端验证登录
router.post('/login', function(req, res){
    var userPhone = req.body.userPhone;
    var password = req.body.password;
    if(userPhone && password){
        MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
            if (err) throw err;
            var dbo = db.db("books");
            dbo.collection("user").find({userPhone: userPhone}).toArray(function(err, resArr) {
                if (err) throw err;
                if(resArr.length>0){
                    password = password + resArr[0].key;
                    var md5 = crypto.createHash('md5');
                    var r = md5.update(password).digest('hex');
                    if(r == resArr[0].password){
                        res.json({code: 1, content: resArr[0]._id});
                    }else{
                        res.json({code: 2, content: "密码错误"});
                    }
                }else{
                    res.json({code: 2, content: "该手机号暂未注册"});
                }
                db.close();
            });
        });
    }else{
        res.json({code: 4, content: "参数异常"});
    }
});

// 查询用户信息
router.post('/findUserById', function(req, res){
    var userInfoId = req.body.userInfoId;
    if(!userInfoId){
        res.json({code:4, content: "参数异常"});
        return false;
    }
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err) throw err;
        var dbo = db.db("books");
        dbo.collection("user").find({_id: ObjectID(userInfoId)}).toArray(function(err, result) {
            if (err) throw err;
            res.json({code:1, content:result[0]});
            db.close();
        });
    });
});

// 分页获取书籍列表
router.post('/findBooksOfPage', function(req, res){
    var dataNumber = req.body.dataNumber;
    var keyWord = req.body.keyWord;
    var data = {
        status: '1'
    }
    if(req.body.classes != '0'){
        data.classes = req.body.classes
    }
    if(keyWord){
        data.$or = [
            {bookName: new RegExp(keyWord)},
            {author: new RegExp(keyWord)}
        ]
    }
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err) throw err;
        var dbo = db.db("books");
        dbo.collection("book").find(data).skip(dataNumber).limit(10).toArray(function(err, result) {
            if (err) throw err;
            res.json({code:1, content:result});
            db.close();
        });
    });
});

// 书籍详情
router.post('/findBookById', function(req, res){
    var id = req.body.bookInfoId;
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err) throw err;
        var dbo = db.db("books");
        dbo.collection("book").find({_id: ObjectID(id)}).toArray(function(err, result) {
            if (err) throw err;
            res.json({code:1, content:result[0]});
            db.close();
        });
    });
});

// 查询书架列表
router.post('/findBookshelfOfPage', function(req, res){
    var userInfoId = req.body.userInfoId;
    var dataNumber = req.body.dataNumber;
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err) throw err;
        var dbo = db.db("books");
        dbo.collection("bookshelf").find({userInfoId: userInfoId}).skip(dataNumber).limit(10).toArray(function(err, result) {
            if (err) throw err;
            res.json({code:1, content:result});
            db.close();
        });
    });
});

// 加入书架
router.post('/addToBookshelf', function(req, res){
    var data = {
        userInfoId: req.body.userInfoId,
        bookInfoId: req.body.bookInfoId,
        bookName: req.body.bookName,
        author: req.body.author,
        bookImg: req.body.bookImg,
        bookSize: req.body.bookSize,
        location: "0"
    }
    for(var k in data){
        if(k != 'location' && !data[k]){
            res.json({code:4, content: "参数异常"});
            return false;
        }
    }
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err) throw err;
        var dbo = db.db("books");
        dbo.collection("bookshelf").find({userInfoId: data.userInfoId, bookInfoId: data.bookInfoId}).toArray(function(err, result) {
            if (err) throw err;
            if(result.length>0){
                res.json({code:2, content: "书籍已存在于书架"});
            }else{
                dbo.collection("bookshelf").insertOne(data, function(err, result){
                    if (err) throw err;
                    res.json({code:1, content:"已添加至书架"});
                })
            }
            db.close();
        });
    });
});

// 下载图片接口
router.get('/downloadImg', function(req, res){
    var img = req.query.fileName;
    if(!img){return}
    var url = path.resolve(__dirname, '../public/scratch_file/', img);
    try{
        fs.accessSync(url);
        res.sendFile(url);
    }catch(e){
        url = path.resolve(__dirname, '../public/books_img/', img);
        res.sendFile(url);
    }
});

// 删除书架书籍
router.post('/delBookshelf', function(req, res){
    var bookInfoId = req.body.bookInfoId;
    var userInfoId = req.body.userInfoId;
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err){
            res.json({code:4, content: "服务器异常"});
            throw err;
        }
        var dbo = db.db("books");
        dbo.collection("bookshelf").deleteOne({userInfoId:userInfoId,bookInfoId: bookInfoId}, function(err, result) {
            if (err){
                res.json({code:4, content: "服务器异常"});
                throw err;
            }
            res.json({code:1, content: "删除成功"});
            db.close();
        });
    });
});

// 查询书架书籍
router.post('/findBookshelfById', function(req, res){
    var bookInfoId = req.body.bookInfoId;
    var userInfoId = req.body.userInfoId;
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        if (err){
            res.json({code:4, content: "服务器异常"});
            throw err;
        }
        var dbo = db.db("books");
        dbo.collection("bookshelf").find({userInfoId:userInfoId,bookInfoId: bookInfoId}).toArray(function(err, result) {
            if (err){
                res.json({code:4, content: "服务器异常"});
                throw err;
            }
            res.json({code:1, content: result});
            db.close();
        });
    });
});

// 分页读取书籍
router.post('/findBookOfPage', function(req, res){
    var userInfoId = req.body.userInfoId;
    var bookInfoId = req.body.bookInfoId;
    var location = req.body.location;
    if(!bookInfoId && !location){
        res.json({code:4, content: "服务器异常"});
        return false
    }
    MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
        var dbo = db.db("books");
        dbo.collection("book").find({_id: ObjectID(bookInfoId)}).toArray(function(err, result) {
            if (err) throw err;
            if(result[0].bookUrl){
                var bookUrl = './public/books_txt/'+result[0].bookUrl;
                fs.open(bookUrl, 'r', function (err, fd) {
                    if (err) throw err;
                    // 读取文件
                    fs.read(fd, buf, 0, buf.length, location, function (err, bytes) {
                        if (err) throw err;
                
                        // 仅输出读取的字节
                        if (bytes > 0) {
                            res.json({code:1, content: buf.slice(0, bytes).toString()});
                        }else{
                            res.json({code:2, content: "终章"});
                        }
                
                        // 关闭文件
                        fs.close(fd, function (err) {
                            if (err) throw err;
                        })
                    })
                })
            }else{
                res.json({code:4, content: "服务器异常"});
            }
            
        });
        var whereStr = {userInfoId: userInfoId,bookInfoId: bookInfoId};  // 查询条件
        var updateStr = {$set: { location: location }};
        dbo.collection("bookshelf").updateOne(whereStr, updateStr, function(err, result) {
            if (err) throw err;
        });
        db.close();
    });
});

// MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
//     var dbo = db.db("books");
//     // 删除
//     // dbo.collection("bookshelf").deleteOne({"_id": ObjectID('5c384e1460e7462390755a67')}, function(err, result) {
//     //     if (err) throw err;
//     // });
//     // 查询
//     dbo.collection("bookshelf").find().toArray(function(err, result) {
//         if (err) throw err;
//         console.log(result);
//     });

//     db.close();
// });

module.exports = router;

Answer 1

MongoClient应该在整个应用生命周期内保持单例，不要在每次请求时再初始化，创建MongoClient的成本很高。