5.6. Declaring Filters

Servlet version 2.3 introduced the concept of filters. Although filters are supported by all servers that support version 2.3 of the servlet API, you must use the version 2.3 DTD in web.xml in order to use the filter-related elements. For details on the DTD, see Section 5.1 (Defining the Header and Root Elements).

Core Note

Filters and the filter-related elements in web.xml are available only in servers that support the Java servlet API version 2.3. Even with compliant servers, you must use the version 2.3 DTD.

Filters are discussed in detail in Chapter 9, but the basic idea is that filters can intercept and modify the request ...

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