小程序：更换头像并转为base64，上传（mpvue）

async uploadPic() {
    mpvue.chooseImage({
        count: 1,
        sizeType: ['original', 'compressed'],
        sourceType: ['album', 'camera'],
        success: (res) => {
            //转换临时文件为base64
            wx.getFileSystemManager().readFile({
                filePath: res.tempFilePaths[0], //选择图片返回的相对路径
                encoding: 'base64', //编码格式
                success: res => { //成功的回调
                    this.icon = 'data:image/png;base64,' + res.data;
                    this.uploadimg(res.data);
                }
            })
        }
    });
},

///请求接口更新用户头像

uploadimg() {
    this.$http.post('/orgAnization/updateIcon', {
        uid: this.LOGIN_INFO.uid,
        icon: this.icon
    }).then((data) => {
        wx.showToast({title: data.message});
    });
},