vue+node实现图片上传及预览的示例方法

本文介绍了vue+node实现图片上传及预览的示例方法，分享给大家，具体如下：

先上效果图

上代码

html部分主要是借助了weui的样式

<template>
 <div>
  <myheader :title="'发布动态'">
   <i class="iconfont icon-fanhui1 left" slot="left" @click="goback"></i>
  </myheader>
  <div class="upload">
   <div v-if="userinfo._id">
    <!--图片上传-->
    <div class="weui-gallery" id="gallery">
     <span class="weui-gallery__img" id="galleryimg"></span>
     <div class="weui-gallery__opr">
      <a href="javascript:" rel="external nofollow" class="weui-gallery__del">
       <i class="weui-icon-delete weui-icon_gallery-delete"></i>
      </a>
     </div>
    </div>
    <div class="weui-cells weui-cells_form">
     <div class="weui-cell">
      <div class="weui-cell__bd">
       <textarea class="weui-textarea" v-model="content" placeholder="你想说啥" rows="3"></textarea>
      </div>
     </div>
     <div class="weui-cell">
      <div class="weui-cell__bd">
       <div class="weui-uploader">
        <div class="weui-uploader__bd">
         <ul class="weui-uploader__files" id="uploaderfiles">
          <li ref="files" class="weui-uploader__file" v-for="(image,index) in images" :key="index"
            :style="'backgroundimage:url(' + image +' )'"><span @click="deleteimg(index)" class="x">×</span></li>
         </ul>
         <div v-show="images.length < maxcount" class="weui-uploader__input-box">
          <input @change="change" id="uploaderinput" class="weui-uploader__input " type="file"
             multiple accept="image/*">
         </div>
        </div>
       </div>
      </div>
     </div>
    </div>
    <a class="weui-btn weui-btn_primary btn-put" style="margin: 20px " @click.prevent.once="put">发送</a>
   </div>
   <unlogin v-else> </unlogin>
  </div>
 </div>
</template>

重点部分在于

<ul class="weui-uploader__files" id="uploaderfiles">
 <li ref="files" class="weui-uploader__file" v-for="(image,index) in images" :key="index"
   :style="'backgroundimage:url(' + image +' )'"><span @click="deleteimg(index)" class="x">×</span></li>
</ul>
<div v-show="!this.$refs.files||this.$refs.files.length < maxcount" class="weui-uploader__input-box">
 <input @change="change" id="uploaderinput" class="weui-uploader__input" type="file"
     multiple accept="image/*">
</div>

通过@change="change"监听图片的上传，把图片转成base64后（后面会讲怎么转base64）将base64的地址加入到images数组，通过v-for="(image,index) in images"把要上传的图片在页面中显示出来，即达到了预览的效果

js部分

data部分

data() {
   return {
    content: '',//分享动态的文字内容
    maxsize: 10240000 / 2,//图片的最大大小
    maxcount: 8,//最大数量
    filesarr: [],//保存要上传图片的数组
    images: []//转成base64后的图片的数组
   }
  }

delete方法

deleteimg(index) {
    this.filesarr.splice(index, 1);
    this.images.splice(index, 1);
   }

change方法

change(e) {
    let files = e.target.files;
    // 如果没有选中文件，直接返回
    if (files.length === 0) {
     return;
    }
    if (this.images.length + files.length > this.maxcount) {
     toast('最多只能上传' + this.maxcount + '张图片！');
     return;
    }
    let reader;
    let file;
    let images = this.images;
    for (let i = 0; i < files.length; i++) {
     file = files[i];
     this.filesarr.push(file);
     reader = new filereader();
     if (file.size > self.maxsize) {
      toast('图片太大，不允许上传！');
      continue;
     }
     reader.onload = (e) => {
      let img = new image();
      img.onload = function () {
       let canvas = document.createelement('canvas');
       let ctx = canvas.getcontext('2d');
       let w = img.width;
       let h = img.height;
       // 设置 canvas 的宽度和高度
       canvas.width = w;
       canvas.height = h;
       ctx.drawimage(img, 0, 0, w, h);
       let base64 = canvas.todataurl('image/png');
       images.push(base64);
      };
      img.src = e.target.result;
     };
     reader.readasdataurl(file);
    }
   }

put方法把filesarr中保存的图片通过axios发送到后端,注意要设置headers信息

put() {
    indicator.open('发布中...');
    let self = this;
    let content = this.content;
    let param = new formdata();
    param.append('content', content);
    param.append('username', this.userinfo._id);
    this.filesarr.foreach((file) => {
     param.append('file2', file);
    });
    self.axios.post('/upload/uploadfile', param, {
     headers: {
      "content-type": "application/x-www-form-urlencoded"
     }
    }).then(function (result) {
     console.log(result.data);
     self.$router.push({path: '/home'});
     indicator.close();
     toast(result.data.msg)
    })
   }

后端通过multer模块保存传输的图片，再把保存下来的图片发送到阿里云oss（这个可以根据自己的使用情况变化）

let filepath;
let filename;

let storage = multer.diskstorage({
  destination: function (req, file, cb) {//计算图片存放地址
    cb(null, './public/img');
  },
  filename: function (req, file, cb) {//图片文件名
    filename = date.now() + '_' + parseint(math.random() * 1000000) + '.png';
    filepath = './public/img/' + filename;
    cb(null, filename)
  }
});
let upload = multer({storage: storage}).any();//file2表示图片上传文件的key

router.post('/uploadfile', function (req, res, next) {
  upload(req, res, function (err) {
    let content = req.body.content || '';
    let username = req.body.username;
    let imgs = [];//要保存到数据库的图片地址数组
    if (err) {
      return res.end(err);
    }
    if (req.files.length === 0) {
      new pyq({
        writer: username,
        content: content
      }).save().then((result) => {
        res.json({
          result: result,
          code: '0',
          msg: '上传成功'
        });
      })
    }
    /*client.delete('public/img/1.png', function (err) {
      console.log(err)
    });*/
    let i = 0;
    req.files.foreach((item, index) => {
      let filepath = `./public/img/${item.filename}`;
      put(item.filename,filepath,(result)=>{
        imgs.push(result.url);
        i++;
        if (i === req.files.length) {
        //foreach循环是同步的，但上传图片是异步的，所以用一个i去标记图片是否全部上传成功
        //这时才把数据保存到数据库
          new pyq({
            content: content,
            writer: username,
            pimg: imgs
          }).save().then(() => {
            res.json({
              code: '0',
              msg: '发布成功'
            });
          })
        }
      })
    })
  })
});

github地址

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。