response.set( 'content-type', mimeType );//設(shè)置返回類型
var stream = fs.createReadStream( imageFilePath );
var responseData = [];//存儲(chǔ)文件流
if (stream) {//判斷狀態(tài)
    stream.on( 'data', function( chunk ) {
      responseData.push( chunk );
    });
    stream.on( 'end', function() {
       var finalData = Buffer.concat( responseData );
       response.write( finalData );
       response.end();
    });
}