微信小程序图书馆实战开发教程

图书馆小程序是一个图书漂流和借阅工具，旨在共享闲置图书，并链接趣味相投的小伙伴。需求上可以满足用户碎片时间的阅读，分享给小伙伴，发布图书以及收藏等。本篇教程给读者介绍这样一个图书馆小程序的实战开发。

技术栈

小程序MINA框架：一个响应的数据绑定框架。分为两块视图层(View)和逻辑层(App Service)

Flex：flex弹性布局

Express : http服务框架

websocket: 前后端消息的实时推送

mongoose: 操作mongodb数据库

pm2: 服务端使用pm2部署，常驻进程

效果图：

微信小程序图书馆实战开发教程

客户端

代码结构

微信小程序中每个页面会有四个文件 .js .json .wxml .wxss

js文件中是页面的逻辑，json文件是页面的一些配置，wxml是小程序的页面结构，wxss为页面的样式。

封装http请求

const request = (obj) => {
if(obj.header){
obj.header.sessionId = session.sessionId;
}else{
obj.header = { sessionId: session.sessionId};
}
wx.request(obj);
}

在请求头中手动加上sessionId,因为小程序没有cookie。

websocket
//连接websocket
wx.connectSocket({
url: \'wss://liudongtushuguan.cn/socket?sessionId=\' + session.sessionId,
});

wx.onSocketOpen(function(res){

});
wx.onSocketClose(function(res){
console.log(\'websocket closed\');
});

wx.onSocketMessage(function(res){ //收到消息的回调
let msg = JSON.parse(res.data);
let msgs = that.data.borrowMessage;
msgs.unshift(msg);
that.setData({ borrowMessage: msgs});
});

//发送socket消息
let data = JSON.stringify({
targetId: bookData.ownerId,
nickName: APP.globalData.userInfo.nickName,
bookName: bookData.title,
time: new Date().toLocaleString(),
bookId: bookId,
wxNum: wxNum,
phoneNum: phoneNum,
msg: msg,
});
wx.sendSocketMessage({
data: data,
});

服务端

代码目录
Express框架实现http服务
const https = require(\'https\');
const fs = require(\'fs\');
const express = require(\'express\')
const cookieParser = require(\'cookie-parser\');
const bodyParser = require(\'body-parser\');
const app = express();
const queryString = require(\'querystring\');
const URL = require(\'url\');
const socket = require(\'./service/socket\');

const router = require(\'./routes/router\').router;

//获取认证证书
var key = fs.readFileSync(\'./key/2_www.liudongtushuguan.cn.key\');
var cert = fs.readFileSync(\'./key/1_www.liudongtushuguan.cn_bundle.crt\');

var options = {
key : key,
cert : cert,
};

app.use(cookieParser());
app.use(bodyParser.json());

const httpsServer = https.createServer(options,app);
httpsServer.listen(443,() =>{
console.log(\'listening 443 port\');
});

socket(httpsServer); //websocket

app.use(router);

小程序规定必须要用https协议。

websocket模块
这里使用ws模块而没有选择使用http://socket.io，因为小程序客户端不支持http://socket.io

const WebSocket = require(\'ws\'); //使用ws模块
const queryString = require(\'querystring\');
const URL = require(\'url\');
const sessions = require(\'./session\');

module.exports = (httpServer) => {

const wss = new WebSocket.Server({server : httpServer});

wss.on(\'connection\',(ws, req) => {
let sessionId = queryString.parse(URL.parse(req.url).query).sessionId;
ws.id = sessionId;
ws.on(\'message\' , (msg) => {
let msgObj = JSON.parse(msg);
if(sessions[msgObj.targetId]){
wss.clients.forEach((client) => {
if(client.id === msgObj.targetId){
let data = {
time : msgObj.time,
borrower :msgObj.nickName,
book :msgObj.bookName,
borrowerId : sessions[sessionId],
bookId : msgObj.bookId,
wxNum : msgObj.wxNum,
phoneNum : msgObj.phoneNum,
msg : msgObj.msg
};
client.send(JSON.stringify(data));
}
});
}
});
});
};
mongoose操作数据库
db.js:

const mongoose = require(\'mongoose\');

mongoose.connect(\'mongodb://app:12345678@127.0.0.1/wxapp\');

const connection = mongoose.connection;
connection.once(\'open\', (err) => {
if(err){
console.log(\'Database connection failure\');
}else{
console.log(\'Database opened\');

}
});

connection.on(\'error\',(err) => {
console.log(\'Mongoose connected error \'+ err);
});

connection.on(\'disconnected\', () => {
console.log(\'Mongoose disconnected\');
});

module.exports = {
connection : connection,
mongoose : mongoose,
};
model.js:

const Schema = mongoose.Schema;

const UserSchema = new Schema({
onlyId : {type: String},
publishedBooks : {type: Array},
borrowedBooks : {type: Array},
borrowMessages : Array,
});

const BookSchma = new Schema({
isbn : String,
title : String,
press : String,
author : String,
rate : String,
tags : String,
image : String,
status : {type : Boolean,default : true},
ownerId : String,
owner : String,
ownerImage : String,
});

const userModel = mongoose.model(\'user\' , UserSchema);
const bookModel = mongoose.model(\'book\' , BookSchma);

module.exports = {
UserModel : userModel,
BookModel : bookModel,
}

获得微信用户的openId

小程序前端会请求微信服务器得到一个code, 将code发送给自己的服务器，然后自己的服务器给微信服务器发送请求，得到微信用户的唯一标识openId

const https = require(\'https\');
const queryString = require(\'querystring\');

const sessions = require(\'./session\');

module.exports = (req, res, next) => {
let code = req.query.code;
let otherRes = res;
DATA.js_code = code;
OPTION.path = PATH + queryString.stringify(DATA);
let wxReq = https.request(OPTION, (res) => {
if(res.statusCode == 200){
let json = \'\';
res.on(\'data\' , (data) => {
json+=data;
});
res.on(\'end\' , () => {
json =JSON.parse(json);
let openId = json.openid;
sessions[openId] = openId;
otherRes.type(\'application/json\');
otherRes.json({
data : {\'sessionId\' : openId},
});
otherRes.status(200);
});
}
});
wxReq.end();
};

总结

图书馆小程序可以由三个人的小团队设计和开发的。对于那些初次开发小程序的新手是很好的提高，从服务端到搭建应用的雏形，实现基本效果，再到最后拆分整合代码，会让开发者也收获了很多。从数据库的设计到后台数据库操作、会话管理、http服务接口一直到前后端数据交互、小程序前端，对程序开发的大致流程有了更进一步的了解，弥补的之前对服务端知识的缺失。

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