//子组件download-file.vue
<template>
 <div></div>
</template>

<script>
export default {
 props: {
  urls: {
   default: ""//通过父组件传递远程图片路径数组
  }
 },
 watch: {
  urls() {
   if (this.urls.length > 0) {
    this.downLoadImage(this.urls);//监听变化
   }
  }
 },
 methods: {
  //拿到图片的临时路径
  getImageInfo(url) {
   var cache = {};
   return new Promise((resolve, reject) => {
    /* 获得要在画布上绘制的图片 */
    if (cache[url]) {
     resolve(cache[url]);
    } else {
     const objExp = new RegExp(
      /^http(s)"getImageInfo:ok") {
         cache[url] = res.path;
         resolve(res.path);
        } else {
         reject(new Error("getImageInfo fail"));
        }
       }
      });
     } else {
      this.cache[url] = url;
      resolve(url);
     }
    }
   });
  },
  downLoadImage(urls) {
   const vm = this;
   let temp = [];
   if (urls.length > 0) {
    urls.map((item, index) => {
     vm.getImageInfo(item).then(res => {
      temp.push(res);
      vm.saveImageToLocal(res);
     });
    });
   }
  },
  saveImageToLocal(path) {
   //保存临时图片到本地
   wx.saveImageToPhotosAlbum({
    filePath: path,
    success(res) {
     console.log("success");
    },
    fail: function(res) {
     console.log(res);
    }
   });
  }
 }
};
</script>

<style>
</style>

//news/detail.vue
//省略代码...
<button @click="download">下载</button>
//省略代码...
<download-file :urls="downLoadUrls" ref="myDownload"></download-file>
//省略代码...
async download() {
  let vm = this;
  const temp = [];
  let data = await vm.$net.get(vm.$apis.articleDetails, {
    id: vm.item.id
  });
  if (data.article.body.length > 0) {
   data.article.body.map((item, index) => {
    if (item.type == "img") {
     temp.push(item.data);
    }
  });
 }
 vm.downLoadUrls = temp;
},