Assuming you're searching against a database and that the form on the JSP page invokes a servlet, you'll need to do something like the following:
In the servlet doGet/doPost method(s):
// get search term from HTML form
String searchTerm = request.getParameter("searchTerm"

;
if (searchTerm == null) {
searchTerm = "";
}
// Build SQL SELECT query (exact match)
String sqlQuery = "SELECT * FROM SomeDatabaseTable WHERE LOWER(SomeColumn) = '" + searchTerm.toLowerCase() + "' "
or if you need to get similar matches then try something like
// Build SQL SELECT query (similar match)
String sqlQuery = "SELECT * FROM SomeDatabaseTable WHERE LOWER(SomeColumn) LIKE '" + searchTerm.toLowerCase() + "%' "
Note: '%' may not be the correct wildcard character for the database you're using. Also, your database may or may not support the LIKE operator. And LOWER may or may not be the correct name of your database's string function to convert to lowercase.