Functions of filters in JSP

What are the functions of filters I know?

1-character Transcoding

Request. setCharacterEncoding ("UTF-8 ");

2. Access Determination

Determine whether there are any illegal operations by using the value in the session

3-character filtering

Content = content. replace ("received characters", "changed ");

A filter is an object that can be preprocessed before the request arrives at Servlet/JSP, and then associated with the corresponding Servlet/JSP in the configuration file web. xml. You can use a filter to act on one or more servlets.

DoFilter (ServletRequest, ServletResponse, FilterChain): This method is used to perform and complete filtering.

Filter tag

<Filter>
<Filter-name> EncodingFilter </filter-name>
<Filter-class> sam. EncodingFilter </filter-class>
</Filter>

<Filter-mapping>
<Filter-name> EncodingFilter </filter-name>
<Url-pattern>/* </url-pattern>
</Filter-mapping>