前端开发微信小程序用户登录

1. 从缓存中读取token，如果有则说明用户已经登陆过小程序了

2. 如果没有token，则说明用户第一次登录

3. 拿到用户的code，在服务端获取openid，同时生成token，返回前端，保存到本地

App({

    onLaunch: function() {

        //调用api从本地缓存中获取token

        var token = wx.getStorageSync(‘token’) || ”

        console.info(‘从本地缓存中获取token数据’)

        if (token == null || token == ”) {

            var that = this

            console.info(‘token is null’)

            that.login()

        } else {

            console.info(‘token is not null’)

        }

    },

    //登录接口，登陆成功后设置全局用户信息

    login: function() {

        //获取授权码code

        wx.login({

            success: function(res) {

                console.info(‘授权码code’)

                var code = res.code

                console.info(code)

                if (code) {

                    //获取用户信息接口

                    wx.getUserInfo({

                        success: function(res) {

                            var userInfo = res.userInfo

                            var nickName = userInfo.nickName

                            var avatarUrl = userInfo.avatarUrl

                            //调用后端登录接口

                            wx.request({

                                url: ‘http://127.0.0.1:3000/login’,

                                data: {

                                    nickName: nickName,

                                    avatarUrl: avatarUrl,

                                    code: code,

                                },

                                success: function(res) {

                                    console.info(res.data)

                                    wx.setStorageSync(

                                        ‘token’,

                                        res.data.usertoken,

                                    )

                                },

                                fail: function(res) {

                                    console.info(‘获取token失败’)

                                    console.info(res)

                                },

                            })

                        },

                    })

                } else {

                    console.info(‘获取用户登录凭证失败’)

                }

            },

        })

    },

})