vue blob实现自定义多sheet数据导出到excel文件

背景：最近vue项目遇到一个需求，就是需要将多个表格分成不同sheet页并导出，之前的工具类只能导出一个sheet页，所以在原有的基础上，调整一下，让它支持多sheet导出。

1. vue blob文件流，这个肯定要的，这个百度一下都有，下面贴出来

(function (view) {
  view.URL = view.URL || view.webkitURL;

  if (view.Blob && view.URL) {
    try {
      new Blob;
      return;
    } catch (e) {}
  }

  // Internally we use a BlobBuilder implementation to base Blob off of
  // in order to support older browsers that only have BlobBuilder
  var BlobBuilder = view.BlobBuilder || view.WebKitBlobBuilder || view.MozBlobBuilder || (function(view) {
    var
      get_class = function(object) {
        return Object.prototype.toString.call(object).match(/^\[object\s(.*)\]$/)[1];
      }
      , FakeBlobBuilder = function BlobBuilder() {
        this.data = [];
      }
      , FakeBlob = function Blob(data, type, encoding) {
        this.data = data;
        this.size = data.length;
        this.type = type;
        this.encoding = encoding;
      }
      , FBB_proto = FakeBlobBuilder.prototype
      , FB_proto = FakeBlob.prototype
      , FileReaderSync = view.FileReaderSync
      , FileException = function(type) {
        this.code = this[this.name = type];
      }
      , file_ex_codes = (
        "NOT_FOUND_ERR SECURITY_ERR ABORT_ERR NOT_READABLE_ERR ENCODING_ERR "
        + "NO_MODIFICATION_ALLOWED_ERR INVALID_STATE_ERR SYNTAX_ERR"
      ).split(" ")
      , file_ex_code = file_ex_codes.length
      , real_URL = view.URL || view.webkitURL || view
      , real_create_object_URL = real_URL.createObjectURL
      , real_revoke_object_URL = real_URL.revokeObjectURL
      , URL = real_URL
      , btoa = view.btoa
      , atob = view.atob

      , ArrayBuffer = view.ArrayBuffer
      , Uint8Array = view.Uint8Array
    ;
    FakeBlob.fake = FB_proto.fake = true;
    while (file_ex_code--) {
      FileException.prototype[file_ex_codes[file_ex_code]] = file_ex_code + 1;
    }
    if (!real_URL.createObjectURL) {
      URL = view.URL = {};
    }
    URL.createObjectURL = function(blob) {
      var
        type = blob.type
        , data_URI_header
      ;
      if (type === null) {
        type = "application/octet-stream";
      }
      if (blob instanceof FakeBlob) {
        data_URI_header = "data:" + type;
        if (blob.encoding === "base64") {
          return data_URI_header + ";base64," + blob.data;
        } else if (blob.encoding === "URI") {
          return data_URI_header + "," + decodeURIComponent(blob.data);
        } if (btoa) {
          return data_URI_header + ";base64," + btoa(blob.data);
        } else {
          return data_URI_header + "," + encodeURIComponent(blob.data);
        }
      } else if (real_create_object_URL) {
        return real_create_object_URL.call(real_URL, blob);
      }
    };
    URL.revokeObjectURL = function(object_URL) {
      if (object_URL.substring(0, 5) !== "data:" && real_revoke_object_URL) {
        real_revoke_object_URL.call(real_URL, object_URL);
      }
    };
    FBB_proto.append = function(data/*, endings*/) {
      var bb = this.data;
      // decode data to a binary string
      if (Uint8Array && (data instanceof ArrayBuffer || data instanceof Uint8Array)) {
        var
          str = ""
          , buf = new Uint8Array(data)
          , i = 0
          , buf_len = buf.length
        ;
        for (; i < buf_len; i++) {
          str += String.fromCharCode(buf[i]);
        }
        bb.push(str);
      } else if (get_class(data) === "Blob" || get_class(data) === "File") {
        if (FileReaderSync) {
          var fr = new FileReaderSync;
          bb.push(fr.readAsBinaryString(data));
        } else {
          // async FileReader won't work as BlobBuilder is sync
          throw new FileException("NOT_READABLE_ERR");
        }
      } else if (data instanceof FakeBlob) {
        if (data.encoding === "base64" && atob) {
          bb.push(atob(data.data));
        } else if (data.encoding === "URI") {
          bb.push(decodeURIComponent(data.data));
        } else if (data.encoding === "raw") {
          bb.push(data.data);
        }
      } else {
        if (typeof data !== "string") {
          data += ""; // convert unsupported types to strings
        }
        // decode UTF-16 to binary string
        bb.push(unescape(encodeURIComponent(data)));
      }
    };
    FBB_proto.getBlob = function(type) {
      if (!arguments.length) {
        type = null;
      }
      return new FakeBlob(this.data.join(""), type, "raw");
    };
    FBB_proto.toString = function() {
      return "[object BlobBuilder]";
    };
    FB_proto.slice = function(start, end, type) {
      var args = arguments.length;
      if (args < 3) {
        type = null;
      }
      return new FakeBlob(
        this.data.slice(start, args > 1 ? end : this.data.length)
        , type
        , this.encoding
      );
    };
    FB_proto.toString = function() {
      return "[object Blob]";
    };
    FB_proto.close = function() {
      this.size = this.data.length = 0;
    };
    return FakeBlobBuilder;
  }(view));

  view.Blob = function Blob(blobParts, options) {
    var type = options ? (options.type || "") : "";
    var builder = new BlobBuilder();
    if (blobParts) {
      for (var i = 0, len = blobParts.length; i < len; i++) {
        builder.append(blobParts[i]);
      }
    }
    return builder.getBlob(type);
  };
}(typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content || this));
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2. Ex2ExcelUtils.js，导出工具类

require('script-loader!file-saver');
require('./Blob');
require('script-loader!xlsx/dist/xlsx.core.min');

/**
 * 支持多sheet
 * @param sheetNames
 * @param ths 表头
 * @param jsonDatas 数据
 * @param defaultTitle
 */
export function export_data_to_excel(sheetNames, ths, jsonDatas, defaultTitle) {
  var wb = new Workbook()
  for(let index in sheetNames){
    let th = ths[index]
    var data = deepCopy(jsonDatas[index]);
    data.unshift(th);
    var ws_name = sheetNames[index];

    var ws = sheet_from_array_of_arrays(data);
    //================表格宽度自适应====================
    /*设置worksheet每列的最大宽度*/
      const colWidth = data.map(row =>
          row.map(val => {
            /*先判断是否为null/undefined*/
            if (val == null || val == undefined || val == "") {
              return {
                wch: 10
              };
            } else if (val.toString().charCodeAt(0) > 255) {
              /*再判断是否为中文*/
              return {
                wch: val.toString().length * 2
              };
            } else {
              return {
                wch: val.toString().length * 1.4
              };
            }
          })
      );
      /*以主表第二行为初始值，因为我的第一行是表格标题，会比较长，所以以主表第二行为初始值*/
      let result = colWidth[1];
      for (let i = 1; i < colWidth.length; i++) {
        for (let j = 0; j < colWidth[i].length; j++) {
          if (result[j]["wch"] < colWidth[i][j]["wch"]) {
            result[j]["wch"] = colWidth[i][j]["wch"];
          }
        }
      }
      ws["!cols"] = result;
    //====================表格宽度自适应-结束=================

    wb.SheetNames.push(ws_name);
    wb.Sheets[ws_name] = ws;
  }

  var wbout = XLSX.write(wb, {bookType: 'xlsx', bookSST: false, type: 'binary'});
  saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}), defaultTitle + ".xlsx")
}

function datenum(v, date1904) {
  if (date1904) v += 1462;
  var epoch = Date.parse(v);
  return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
}

function sheet_from_array_of_arrays(data, opts) {
  var ws = {};
  var range = {s: {c: 10000000, r: 10000000}, e: {c: 0, r: 0}};
  for (var R = 0; R != data.length; ++R) {
    for (var C = 0; C != data[R].length; ++C) {
      if (range.s.r > R) range.s.r = R;
      if (range.s.c > C) range.s.c = C;
      if (range.e.r < R) range.e.r = R;
      if (range.e.c < C) range.e.c = C;
      var cell = {v: data[R][C]};
      if (cell.v == null) continue;
      var cell_ref = XLSX.utils.encode_cell({c: C, r: R});
      if (typeof cell.v === 'number') cell.t = 'n';
      else if (typeof cell.v === 'boolean') cell.t = 'b';
      else if (cell.v instanceof Date) {
        cell.t = 'n';
        cell.z = XLSX.SSF._table[14];
        cell.v = datenum(cell.v);
      }
      else cell.t = 's';

      ws[cell_ref] = cell;
    }
  }
  if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range);
  return ws;
}

function Workbook() {
  if (!(this instanceof Workbook)) return new Workbook();
  this.SheetNames = [];
  this.Sheets = {};
}

function s2ab(s) {
  var buf = new ArrayBuffer(s.length);
  var view = new Uint8Array(buf);
  for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
  return buf;
}

3. 上述两个文件，放在同一个目录下，以下是调用示例

// 文件名
const excelName = '多sheet页数据导出'
// 声名每个sheet页的名称
let sheetNames = ['sheet1', 'sheet2', 'sheet3']
// 每个sheet页的表头
let ths = [[], [], []]
// 每个sheet页的数据内容
let jsonDatas = [[], [], []]

// sheet1
ths[0] = ['表头A1', '表头A2', '表头A3', '表头A4']
jsonDatas[0] = [['值A1', '值A2', '值A3', '值A4'],['值B1', '值B2', '值B3', '值B4']]
// sheet2
ths[1] = ['表头A11', '表头A21', '表头A31', '表头A41']
jsonDatas[1] = [['值A11', '值A21', '值A31', '值A41'],['值B11', '值B21', '值B31', '值B41']]
// sheet3
ths[2] = ['表头A12', '表头A22', '表头A32', '表头A42']
jsonDatas[2] = [['值A12', '值A22', '值A32', '值A42'],['值B12', '值B22', '值B32', '值B42']]

const { export_data_to_excel} = require('./Ex2ExcelUtils')
export_data_to_excel(sheetNames, ths, jsonDatas, excelName)

最后：前端或后端导出文件，可以看自己需求。数据量比较少的时候，或页面展示的是所有数据的时候，使用前端js直接导出文件，比较方便，因为不用重查接口，减少了交互。若数据量比较大，或页面展示的是分页时，推荐走后端接口导出文件，因为没法拿到完整的数据，而且大数据量从接口返回到前端，对前端负担也不友好。