ch. 13 filters and wrappers
TRANSCRIPT
Chapter 13 Filters and Wrappers
Intercepting the requests & responses
Filters
Provide universal functions that can be "attached" to any type of servlet or JSP page. • Authentication • Logging and auditing • Image conversion • Data compression • Localization • XSL/T transformations of XML content
Filters API
Filter, FilterChain, and FilterConfig interfaces in the javax.servlet package. • Define a filter by implementing the Filter interface. • A filter chain, • passed to a filter by the container, • provides a mechanism for invoking a series of filters.
• FilterConfig contains initialization data.
Filters• Security checks • Reformat headers and bodies • Audit/log
• Compress • Append • Create new
Modular and Reconfigurable (in DD)
Filters are just like servlets
• The Container knows their API • The Container manages their lifecycle • They are declared in DD
Request tracking filter
Stack
Declare and order(in DD)
Compression Filter(version 1)
Compression Filter(conceptual view)
API
Compression Filter(version 2)
Compression Filter(version 3)
Final Code
Compression Wrapper – helper class