get path of selected directory in textbox .

 Hi,
In my web application  , user requires  one option he shuld  select only directory  ,

for this   requirment is

one  Textbox  and beside this i  taken one button control
when he  click button  how to open a browse window  and after  he selects any directory , how to retreive  seleted  directory path  in  Textbox

 
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