setBase64Save(base64File) {
    const fsm = wx.getFileSystemManager();
    let extName = base64File.match(/data\:\S+\/(\S+);/)
    if (extName) {
     extName = extName[1]
    }
    let fileName = Date.now() + '.' + extName
    return new Promise((resolve, reject) => {
     let filePath = wx.env.USER_DATA_PATH + '/' + fileName
     fsm.writeFile({
      filePath,
      data: base64File.replace(/^data:\S+\/\S+;base64,/, ''), 
      encoding: 'base64',
      success:(res)=>{
       console.log('filePath',filePath); 
       resolve(filePath);
      },
      fail() {
       reject('写入失败');
      },
     });
    });
    },