// 引入请求模块
      var request = require('request');
      // 此刻拿到了图片的src
      let imgSrc = '真实的图片地址';
      try {
        let opts = {
          url: imgSrc
        };
        var time = new Date().getTime(); 
        let path = "/tmp/"+ time+".png"; 
        await new Promise((resolve, reject) => {
          request.get(opts).on('response', response => {
            console.log("img type:", response.headers['content-type']);
          }).pipe(fs.createWriteStream(path)).on("error", e => {
            console.log("pipe error", e);
            resolve('');
          }).on("finish", () => {
            console.log("finish");
            resolve("ok");
          }).on("close", () => {
            console.log("close");
            resolve();
          });
        });
      } catch (e) {
        console.log(e);
      }