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var extend = require("extend");
var fs = require("fs");
var excelExport = require('excel-export');
var guid=require('guid');
var path=require('path');
var excel=function(){
this.req=null;
this.resp=null;
};
/**
* 生成excel文件
* @param params
*/
excel.prototype.createExcel=function(params){
var setting={savePath:"uploadFile/excel/"};
setting=extend({},setting,params);
var uuid=guid.create();
var data=params.data||"";
var result = excelExport.execute(data);
var name='excel'+uuid+'.xlsx';
var filePath= path.resolve(setting.savePath, name);
fs.writeFile(filePath, result, 'binary',function(err){
setting.cb(filePath);
});
}
/**
* 计算上次的断点信息
* @param range
* @returns {number}
* @private
*/
excel.prototype._calStartPosition = function(range) {
var startPos = 0;
if( typeof range != 'undefined') {
var startPosMatch = /^bytes=([0-9]+)-$/.exec(range);
startPos = Number(startPosMatch[1]);
}
return startPos;
}
excel.prototype._configHeader = function(config) {
var startPos = config.startPos,
fileSize = config.fileSize,
resp = this.resp;
// 如果startPos为0，表示文件从0开始下载的，否则则表示是断点下载的。
if(startPos == 0) {
resp.setHeader('Accept-Range', 'bytes');
} else {
resp.setHeader('Content-Range', 'bytes ' + startPos + '-' + (fileSize - 1) + '/' + fileSize);
}
resp.writeHead(206, 'Partial Content', {
'Content-Type' : 'application/octet-stream'
});
}
excel.prototype._init = function(filePath, down) {
var config = {};
var self = this;
fs.stat(filePath, function(error, state) {
if(error)
throw error;
config.fileSize = state.size;
var range = self.req.headers.range;
config.startPos = self._calStartPosition(range);
self.config = config;
self._configHeader(config);
down();
});
}
/**
* 下载文件
* @param filePath 文件路径
* @param req
* @param res
* @param isDeleted 下载完成后是否删除文件，true删除
*/
excel.prototype.download = function(filePath,req,res,isDeleted) {
var self = this;
self.req=req;
self.resp = res;
path.exists(filePath, function(exist) {
if(exist) {
self._init(filePath, function() {
var config = self.config
resp = self.resp;
fReadStream = fs.createReadStream(filePath, {
encoding : 'binary',
bufferSize : 1024 * 1024,
start : config.startPos,
end : config.fileSize
});
fReadStream.on('data', function(chunk) {
resp.write(chunk, 'binary');
});
fReadStream.on('end', function() {
//是否删除文件
if(isDeleted) {
fs.unlink(filePath, function (err, res) {
});
}
resp.end();
});
});
}
else {
console.log('文件不存在！');
return;
}
});
}
module.exports=new excel();
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