前言
首先，我们看一下微信开放文档中的一张图：
上面的一幅图中清楚地介绍了微信登录整个过程，下面对图上所示进行总结：
一、二维码的获得
用户打开登录网页后，登录网页后台根据微信OAuth2.0协议向微信开发平台请求授权登录，并传递事先在微信开发平台中审核通过的AppID和AppSecrect等参数;
微信开发平台对AppID等参数进行验证，并向登录网页后台返回二维码;
登录网页后台将二维码传送至前台进行显示;
二、微信客户端授权登录
用户使用微信客户端扫描二维码并授权登录;
微信客户端将二维码特定的uid与微信账号绑定，传送至微信开发平台;
微信开发平台验证绑定数据，调用登录网页后台的回调接口，发送授权临时票据code;
三、网页后台请求数据
登录网页后台接收到code，表明微信开发平台同意数据请求;
登录网页后台根据code参数，再加上AppID和AppSecret请求微信开发平台换取access_token;
微信开发平台验证参数，并返回access_token;
登录网页后台收到access_token后即可进行参数分析获得用户账号数据。
https://www.houdianzi.com/ logo设计公司
实现
了解了大致原理之后，我们就开始简单实现这个逻辑。因为没有直接调用微信开发平台，所以这里只是演示效果。你也可以通过访问：
https://www.maomin.club/qrcodelogin/
这个我的线上网址体验一下。以下代码是主要逻辑，结合线上网址体验更容易理解。
let http = require("http");
let express = require("express");
let qrcode = require("qr-image");
let app = express();
let path = require("path");
let server = http.createServer(app);
let url = require("url");
let fs = require("fs");
let UUID = require("uuid-js");
let generatehtml = null;
app.use(express.static("./public"));
/*
* Description: 读取网页文件，用于替换关键字，相当于简易模板
* Params:
* sessionID - 生成的uid
* req - 网页请求
* res - 网页应答
* fileName - 网页文件所在路径
*/
generatehtml = function (sessionID, req, res, fileName) {
fs.readFile(fileName, "UTF-8", function (err, data) {
if (!err) {
data = data.replace(/SESSION_UID/g, sessionID);
res.writeHead(200, {
"Content-Type": "text/html; charset=UTF-8",
});
res.end(data);
} else {
console.log(err);
res.writeHead(404, {
"Content-Type": "text/html; charset=UTF-8",
});
res.end();
}
});
};
/*
* Description: 写入jsON文件
* Params:
* fileName - JSON文件所在路径
* uid - 生成的uid
* writeData - 需要写入的JSON格式数据
*
*/
let setJSONValue = function (fileName, uid, writeData) {
let data = fs.readFileSync(fileName);
let users = JSON.parse(data.toString());
let addFlag = true;
let delFlag = writeData === null;
for (let i = 0; i < users.data.length; i++) {
if (users.data[i].uid === uid) {
addFlag = false;
if (delFlag) {
users.data.splice(i, 1);
} else {
users.data[i].status = writeData.status;
console.log(
"writeJSON: " + JSON.stringify(users.data[i]) + " modified."
);
}
}
}
if (addFlag) {
users.data.push(writeData);
console.log("writeJSON: " + JSON.stringify(writeData) + " inserted.");
}
// 同步写入文件
let writeJSON = JSON.stringify(users);
fs.writeFileSync(fileName, writeJSON);
};
/*
* Description: 读取JSON文件（要返回数据，选择同步读取）
* Params:
* fileName - JSON文件所在路径
* uid - 生成的uid
*
*/
getJSONValue = function (fileName, uid) {
let readData = null;
// 同步读取文件
let data = fs.readFileSync(fileName);
let users = JSON.parse(data.toString());
for (let i = 0; i < users.data.length; i++) {
if (users.data[i].uid === uid) {
readData = JSON.stringify(users.data[i]);
break;
}
}
return readData;
};
// 显示网站首页
app.get("/", function (req, res) {
// 生成唯一的ID
let uid = UUID.create();
console.log("uid: '" + uid + "' generated.");
// 替换网页模板内的UID关键字
generateHTML(uid, req, res, path.join(__dirname, "/views/main.html"));
});
// 生成二维码图片并显示
app.get("/qrcode", function (req, res, next) {
let uid = url.parse(req.url, true).query.uid;
try {
if (typeof uid !== "undefined") {
// 写入二维码内的网址，微信扫描后自动跳转。下面的网址是我的网址，https://www.maomin.club/qrcodelogin ，你可以换成自己的线上网址或者本地服务器。加上后面的"/scanned?uid="
let jumpURL = "https://www.maomin.club/qrcodelogin/scanned?uid=" + uid;
// 生成二维码(size：图片大小， margin: 边框留白)
let img = qrcode.image(jumpURL, { size: 6, margin: 2 });
res.writeHead(200, { "Content-Type": "image/png" });
img.pipe(res);
} else {
res.writeHead(414, { "Content-Type": "text/html" });
res.end("<h1>414 Request-URI Too Large</h1>");
}
} catch (e) {
res.writeHead(414, { "Content-Type": "text/html" });
res.end("<h1>414 Request-URI Too Large</h1>");
}
});
// 显示手机扫描后的确认界面
app.get("/scanned", function (req, res) {
let uid = url.parse(req.url, true).query.uid;
if (typeof uid !== "undefined") {
generateHTML(uid, req, res, path.join(__dirname, "/views/confirm.html"));
console.log("uid: '" + uid + "' scanned.");
// 获取JSON文件内对应uid的数据，更改其数据状态
let jsonData = getJSONValue(path.join(__dirname, "/bin/data.json"), uid);
if (jsonData === null) {
jsonData = {
uid: uid,
status: "scanned",
name: "USER",
};
} else {
jsonData = JSON.parse(jsonData);
jsonData.status = "scanned";
}
// 写入JSON文件
setJSONValue(path.join(__dirname, "/bin/data.json"), uid, jsonData);
} else {
res.writeHead(414, { "Content-Type": "text/html" });
res.end("<h1>414 Request-URI Too Large</h1>");
}
});
// 在确认界面操作的响应
app.get("/confirmed", function (req, res) {
let uid = url.parse(req.url, true).query.uid;
let operate = url.parse(req.url, true).query.operate;
if (typeof uid !== "undefined") {
console.log("uid: '" + uid + "' " + operate);
let jsonData = getJSONValue(path.join(__dirname, "/bin/data.json"), uid);
let status = operate === "confirm" ? "verified" : "canceled";
if (jsonData === null) {
jsonData = {
uid: uid,
status: status,
name: "USER",
};
} else {
jsonData = JSON.parse(jsonData);
jsonData.status = status;
}
setJSONValue(path.join(__dirname, "/bin/data.json"), uid, jsonData);
if (status === "verified") {
res.writeHead(200, { "Content-Type": "text/html" });
res.end("<h1>登录成功!</h1>");
} else {
res.writeHead(200, { "Content-Type": "text/html" });
res.end("<h1>Canceled!</h1>");
}
} else {
res.writeHead(414, { "Content-Type": "text/html" });
res.end("<h1>414 Request-URI Too Large</h1>");
}
});
// 响应主页不断的AJAX请求
app.get("/verified", function (req, res) {
let uid = url.parse(req.url, true).query.uid;
// normal - 没有任何触发
// scanned - 已扫描
// canceled - 已取消
// verified - 已验证
let dataStatus = {
cmd: "normal",
user: "",
};
console.log("uid: '" + uid + "' query ...");
if (typeof uid !== "undefined") {