too long

I have a program that provide step registration1,step registration2. My structure like this:

localhost/bandung/registration.php

then when submit button, the page will send parameter

localhost/bandung/registration.php?user=xxxxxx

Can I change the extention of php to html but still have the parameter like:

localhost/bandung/registration.html?user=xxxxxx

Create in your bandung folder a new htaccess file. Then add the following lines in it:

# Set Rewrite Engine on
RewriteEngine on

# Create rewrite rule for your registration.php
RewriteRule ^registration.html?user=(.*)$ registration.php?user=$1 [R=301,L]

RewriteRule ^(.*)\.php $1.html [R=301,L]
RewriteRule ^(.*)\.html $1.php

edit after pulling white rabbit out of the hat

RewriteEngine on  
RewriteBase /

RewriteCond %{THE_REQUEST} (.*)\.php  
RewriteRule ^(.*)\.php $1.html [R=301,L]  

RewriteCond %{THE_REQUEST} (.*)\.html  
RewriteRule ^(.*)\.html $1.php [L]