基于Vue实现文件上传的几种实现方式_Javascript

文件上传的几种实现方式

form-data、base64、缩略图、进度条、拖拽上传、切片上传

1. form-data方式上传

主要使用form表单方式实现文件上传

let formdata = new formdata();
console.log(this.file);
formdata.append('file', this.file);
formdata.append('filename', this.file.name);
instance.post('/upload_single', formdata).then(res => {
    if (+res.code === 0) {
        this.filetip = '图片上传成功!'
        return;
    }
    return promise.reject(res.codetext);
}).catch(err => {
    console.log(err);
})

2. base64方式上传

使用fildreader获取文件的base64，将其上传

let base64 = await changebase64(that.file);
try {
    const data = await instance
        .post('/upload_single_base64', {
            file: encodeuricomponent(base64), // 防止乱码
            filename: that.file.name
        },{
            headers: {
                'content-type': 'application/x-www-form-urlencoded',
            }
        })
    const { code } = data;
    if (code === 0) {
        this.filetip = '文件上传成功!';
    }
    throw data.codetext; // 抛出异常
} catch (error) {
	console.log(error);
}

3. 文件缩略图显示，文件hash获取

根据文件内容展示缩略图(主要用于图片)，根据内容获取hash值判断后端是否存在该文件，节省上传时间

// 获取文件hash值
const changebuffer = (file) => {
    return new promise((resolve) => {
        let filereader = new filereader();
        filereader.readasarraybuffer(file);
        filereader.onload = (e) => {
            let buffer = e.target.result;
            const spark = new sparkmd5.arraybuffer();
            spark.append(buffer);
            const hash = spark.end();
            const suffix = /\.([0-9a-za-z]+)$/.exec(file.name)[1];
            resolve({
                buffer,
                hash,
                suffix,
                filename: `${hash}.${suffix}`,
            });
        };
    });
};
// 展示缩略图
let base64 = await changebase64(file);
upload_abber_img.src = base64;

4. 文件上传进度条实现

展示文件上传进度

try {
    let formdata = new formdata();
    formdata.append('file', this.file);
    formdata.append('filename', this.file.name);
    const data = await instance.post('/upload_single', formdata, {
        onuploadprogress: (e) => {
            const { loaded, total } = e;
            upload_progress.style.display = 'block';
            upload_progrees_value.style.width = `${ (loaded / total) * 100 }%`;
        },
    });
    if (+data.code === 0) {
        upload_progrees_value.style.width = `100%`;
        this.filetip = '文件上传成功!'
        return;
    }
    throw data.codetext;
} catch (error) {
    console.log(e);
    this.filetip = '文件上传失败!'
} finally {
    upload_progress.style.display = 'none';
    upload_progrees_value.style.width = `0%`;
}

5. 文件拖拽上传

使用原生js事件 dragenter 、drop 、dragover 实现

dragenter(e) {
	e.preventdefault();
},
drop(e) {
	e.preventdefault();
    const {
        datatransfer: { files },
    } = e;
    const file = files[0];
    this.filetip = uploadfile(file);
},
dragover(e) {
    e.preventdefault();
},
uploadchange(e) {
    const file = e.target.files[0];
    this.filetip = uploadfile(file);
},
    
const uploadfile = (file) => {
  const that = this;
  if (!file) {
    alert('请选择您要上传的文件~');
    return;
  }
  let formdata = new formdata();
  formdata.append('file', file);
  formdata.append('filename', file.name);
  let flag = false;
  flag = instance
    .post('/upload_single', formdata)
    .then(res => {
      if (res.code === 0) {
        return true;
      }
      return promise.reject(res.codetext);
    })
    .catch(err => {
      console.log(err);
    })
  return flag ? '文件上传成功!': '文件上传失败!';
}

6. 大文件切片上传

首先确定上传规模数量，判断当前文件可以切出多少切片，
利用bole.prototype.slice() 方法对文件进行切片并且对每个文件片作唯一标识(hash)，
从服务器获取已经上传的切片，判断切片是否存在
将切片全部上传后，后端进行合并处理

let chunklist = [], 
    alreadychunklist = [], 
    maxsize = 1024 * 1024,
    maxcount = math.ceil(this.file.size / maxsize),
    index = 0;
const { hash, suffix } = await this.filehash(this.file);
if (maxcount > 10) {
    // 如果切片数量大于最大值
    maxsize =this.file.size / 10; // 则改变切片大小
    maxcount = 10;
}

while (index < maxcount) {
    chunklist.push({
        file: this.file.slice(index * maxsize, (index + 1) * maxsize),
        filename: `${hash}_${index + 1}.${suffix}`,
    });
    index++;
}

// 先获取已经上传的切片
const data = await instance.post(
    '/upload_already',
    {
        hash: hash,
    },
    {
        headers: {
            'content-type': 'application/x-www-form-urlencoded',
        },
    }
);
index = 0;

const clear = () => {
    upload_progress.style.display = 'none';
    upload_progrees_value.style.width = '0%'
}
const complate = async () => {
    index++;
    upload_progress.style.display = 'block';
    upload_progrees_value.style.width = `${ (index / maxcount) * 100 }%`;
    if (index < maxcount) {
        return;
    }
    upload_progrees_value.style.width = `100%`;
    try {
        let res = await instance
        .post('/upload_merge', 
              {
            hash,
            maxcount
        }, 
              {
            headers: {'content-type': 'application/x-www-form-urlencoded'}
        }
             );
        if (res.code === 0) {
            this.filetip = '大文件切片上传成功!';
            clear();
            return;
        }
        throw data.codetext;
    } catch (error) {
        clear();
    }
}

const { filelist } = data;
alreadychunklist = filelist;
chunklist.foreach(item => {
    if (alreadychunklist.length > 0 && alreadychunklist.includes(item.filename)) {
        debugger
        // 切片已经存在
        complate()
        return;
    }
    const fm = new formdata();
    fm.append('file', item.file);
    fm.append('filename', item.filename);
    instance
        .post('/upload_chunk', fm)
        .then(data => {
        if (+data.code === 0) {
            complate();
            return;
        }
        return promise.reject(data.codetext);
    })
        .catch(() => {
        this.filetip = '上传失败';
        clear();
    })
});

源码 https://github.com/archer0621/fileupload