var readStream = fs.createReadStream(decodeURIComponent(root + filepath.pathname)); // 必须解码url
 readStream.pipe(res); // 管道传输
 res.writeHead(200,{
   'Content-Type' : contType
 });

 // 出错处理
 readStream.on('error', function() {
   res.writeHead(404,'can not find this page',{
     'Content-Type' : 'text/html'
   });
   readStream.pause();
   res.end('404 can not find this page');
   console.log('error in writing or reading ');
 });

var readStream = fs.createReadStream(decodeURIComponent(root + filepath.pathname));
 res.writeHead(200,{
   'Content-Type' : contType
 });

 // 当有数据可读时，触发该函数，chunk为所读取到的块
 readStream.on('data',function(chunk) {
   res.write(chunk);
 });

 // 出错时的处理
 readStream.on('error', function() {
   res.writeHead(404,'can not find this page',{
     'Content-Type' : 'text/html'
   });
   readStream.pause();
   res.end('404 can not find this page');
   console.log('error in writing or reading ');
 });

 // 数据读取完毕
 readStream.on('end',function() {
   res.end();
 });

fs.readFile(decodeURIComponent(root + filepath.pathname), function(err, data) {
   if(err) {
     res.writeHead(404,'can not find this page',{
       'Content-Type' : 'text/html'
     });
     res.write('404 can not find this page');

   }else {
     res.writeHead(200,{
       'Content-Type' : contType
     });
     res.write(data);
   }
   res.end();
 });