//第一次请求登录接口时保存到sessionid中

success: function (res) {

          wx.hideLoading();

          wx.removeStorageSync('sessionid');//每次登录时清楚缓存

          if (res.data.code == "0000") {

            if (res.data.data.roleList[0].value =='student'){

              wx.showToast({

                title: '登录成功',

                icon: 'success',

                duration: 1000

              })

              wx.setStorageSync('sessionid', res.header['Set-Cookie']); //保存Cookie到Storage

            }

          } else {

            wx.showToast({

              title: '登录失败',

              icon: 'none',

              duration: 2000

            })

          }

        },

wx.request({

      url: 'https://xxxx/examResult/selectWxListStudentStudyStatistic',

      method: 'post',

      header: {

        'content-type': 'application/x-www-form-urlencoded',//解决请求不到数据

        'cookie': wx.getStorageSync("sessionid")//读取sessionid,当作cookie传入后台将PHPSESSID做session_id使用

      },

      success: function (res) {

          wx.hideLoading();//去掉loading

      },

      fail: function (e) {

        wx.showToast({

          title: '服务器出现错误',

          icon: 'none',

          duration: 2000

        })

      }

    })