public String getStringValue ( DataBinder binder ) { // binder can't get a non existent param if ( this . name == null || this . name . equals ( "" ) ) { return null ; } String value = ( String ) binder . getLocal ( this . name ) ; if ( value == null && this . required ) { throw new IllegalArgumentException ( "Parameter " + name + " is required" ) ; } return value ; }
Get the string value from binder .