filterRegistration.addInitParameter

() is a method used to add initialization parameters to a filter registration. These parameters are used to configure the filter when it is initialized by the servlet container.

Here is an example of using the addInitParameter() method to add an initialization parameter to a filter registration:

FilterRegistration.Dynamic registration = servletContext.addFilter("MyFilter", MyFilter.class);
registration.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class), true, "/*");
registration.setInitParameter("myParameter", "myValue");

In this example, a new filter registration is created for a filter named "MyFilter" and mapped to all URL patterns. The setInitParameter() method is used to add a parameter named "myParameter" with a value of "myValue" to the filter registration.

When the filter is initialized by the servlet container, it can access this parameter using the getInitParameter() method.

public class MyFilter implements Filter {
    private String myParameter;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        myParameter = filterConfig.getInitParameter("myParameter");
    }

    // ...
}

In this example, the init() method of the MyFilter class retrieves the value of the "myParameter" parameter from the filter configuration using the getInitParameter() method. The filter can then use this parameter to customize its behavior.