基于vue+axios+lrz.js微信端图片压缩上传方法

<input ref="file" type="file" accept="image/jpeg,image/png" @change="selectImgs" />

<input ref="file" type="file" accept="image/*" @change="selectImgs" />

<input ref="file" type="file" accept="image/*" capture="camera" @change="selectImgs" />

selectImgs () {
 let file = this.$refs.file.files[0]
 lrz(file, { width: 450, fieldName: 'file' }).then((rst) => {
  var xhr = new XMLHttpRequest()
  xhr.open('POST', 'http://xxx.com/upload')

  xhr.onload = () => {
   if (xhr.status === 200 || xhr.status === 304) {
    // 无论后端抛出何种错误，都会走这里
    try {
     // 如果后端跑异常,则能解析成功, 否则解析不成功
     let resp = JSON.parse(xhr.responseText)
     console.log('response: ', resp)
    } catch (e) {
     this.imageUrl = xhr.responseText
    }
   }
  }

  // 添加参数
  rst.formData.append('folder', 'wxAvatar') // 保存的文件夹
  rst.formData.append('base64', rst.base64)
  // 触发上传
  xhr.send(rst.formData)

  return rst
 })
}

<template>
 <div class="imgUploader">
  <section v-if="imageUrl"
       class="file-item ">
   <img :src="imageUrl"
      alt="">
   <span class="file-remove"
      @click="remove()">+</span>
  </section>
  <section v-else
       class="file-item">
   <div class="add">
    <svg-icon v-if="!text"
         class="icon"
         icon-class="plus" />
    <span v-if="text"
       class="text">{{text}}</span>
    <input type="file"
        accept="image/*"
        @change="selectImgs"
        ref="file">
   </div>
  </section>
 </div>
</template>

<script>
import lrz from 'lrz'
export default {
 props: {
  text: String,
  // 压缩尺寸,默认宽度为450px
  size: {
   type: Number,
   default: 450
  }
 },
 data () {
  return {
   img: {
    name: '',
    src: ''
   },
   uploadUrl: 'http://ff-ff.xxx.cn/UploaderV2/Base64FileUpload',
   imageUrl: ''
  }
 },
 watch: {
  imageUrl (val, oldVal) {
   this.$emit('input', val)
  },
  value (val) {
   this.imageUrl = val
  }
 },
 mounted () {
  this.imageUrl = this.value
 },
 methods: {
  // 选择图片
  selectImgs () {
   let file = this.$refs.file.files[0]
   lrz(file, { width: this.size, fieldName: 'file' }).then((rst) => {
    var xhr = new XMLHttpRequest()
    xhr.open('POST', this.uploadUrl)

    xhr.onload = () => {
     if (xhr.status === 200 || xhr.status === 304) {
      // 无论后端抛出何种错误，都会走这里
      try {
       // 如果后端跑异常,则能解析成功, 否则解析不成功
       let resp = JSON.parse(xhr.responseText)
       console.log('response: ', resp)
      } catch (e) {
       this.imageUrl = xhr.responseText
      }
     }
    }

    // 添加参数
    rst.formData.append('folder', this.folder) // 保存的文件夹
    rst.formData.append('base64', rst.base64)
    // 触发上传
    xhr.send(rst.formData)

    return rst
   })
  },
  // 移除图片
  remove () {
   this.imageUrl = ''
  }
 }
}
</script>

<style lang="less" scoped>
.imgUploader {
 margin-top: 0.5rem;
 .file-item {
  float: left;
  position: relative;
  width: 100px;
  text-align: center;
  left: 2rem;
  img {
   width: 100px;
   height: 100px;
   border: 1px solid #ececec;
  }
  .file-remove {
   position: absolute;
   right: 0px;
   top: 4px;
   width: 14px;
   height: 14px;
   color: white;
   cursor: pointer;
   line-height: 12px;
   border-radius: 100%;
   transform: rotate(45deg);
   background: rgba(0, 0, 0, 0.5);
  }

  &:hover .file-remove {
   display: inline;
  }
  .file-name {
   margin: 0;
   height: 40px;
   word-break: break-all;
   font-size: 14px;
   overflow: hidden;
   text-overflow: ellipsis;
   display: -webkit-box;
   -webkit-line-clamp: 2;
   -webkit-box-orient: vertical;
  }
 }
 .add {
  width: 100px;
  height: 100px;
  float: left;
  text-align: center;
  line-height: 100px;
  font-size: 30px;
  cursor: pointer;
  border: 1px dashed #40c2da;
  color: #40c2da;
  position: relative;
  background: #ffffff;
  .icon {
   font-size: 1.4rem;
   color: #7dd2d9;
   vertical-align: -0.25rem;
  }
  .text {
   font-size: 1.2rem;
   color: #7dd2d9;
   vertical-align: 0.25rem;
  }
 }
}
input[type="file"] {
 position: absolute;
 left: 0;
 top: 0;
 width: 100%;
 height: 100%;
 border: 1px solid #000;
 opacity: 0;
}
</style>

/// <summary>
/// 图片文件base64上传
/// </summary>
/// <param name="folder">对应文件夹位置</param>
/// <param name="base64">图片文件base64字符串</param>
/// <returns></returns>
public ActionResult Base64FileUpload(string folder, string base64)
{
  var context = System.Web.HttpContext.Current;
  context.Response.ClearContent();
  // 因为前端调用时，需要做跨域处理
  context.Response.AddHeader("Access-Control-Allow-Origin", "*");
  context.Response.AddHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS");
  context.Response.AddHeader("Access-Control-Allow-Headers", "content-type");
  context.Response.AddHeader("Access-Control-Max-Age", "30");
  if (context.Request.HttpMethod.Equals("OPTIONS"))
  {
    return Content("");
  }

  var resultStr = base64.Substring(base64.IndexOf(",") + 1);//需要去掉头部信息，这很重要
  byte[] bytes = Convert.FromBase64String(resultStr);
  var fileName = Guid.NewGuid().ToString() + ".png";
  if (folder.IsEmpty()) folder = "folder";
  //本地上传
  string root = string.Format("/Resource/{0}/", folder);
  string virtualPath = root + fileName;
  string path = Server.MapPath("~" + virtualPath);
  //创建文件夹
  if (!Directory.Exists(Path.GetDirectoryName(path)))
  {
    Directory.CreateDirectory(Path.GetDirectoryName(path));
  }
  System.IO.MemoryStream ms = new System.IO.MemoryStream(bytes);//转换成无法调整大小的MemoryStream对象
  System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(ms);
  bitmap.Save(path, System.Drawing.Imaging.ImageFormat.Png);//保存到服务器路径
  ms.Close();//关闭当前流，并释放所有与之关联的资源
  return Content(Net.Url + virtualPath); //返回文件路径
}