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java.lang.Object | +--javax.servlet.GenericServlet | +--javax.servlet.http.HttpServlet | +--com.mortbay.Servlets.LookAndFeelServlet
LookAndFeel Servlet
The LookAndFeel Servlet serves resources as the body of html pages which it wraps in a certain LookAndFeel. The LookAnd Feel it uses is given in the "PageType" init parameter, but each individual request must supply a "Heading" query parameter at the minimum. All other query parameters given in the request are passed to the Page as Page parameters.
The LookAndFeel Servlet is thus good for using for formatting help pages in their proper LookAndFeel, since a particular instance of the LookAndFeel Servlet can be configured with the correct LookAndFeel for the referring pages and then the individual requests override parameters with the settings from the referring page.
The resource is described in the request pathInfo, prefixed with a path given in the "ResourceBase" init parameter. The page heading is in the "Heading" query parameter.
Constructor Summary | |
LookAndFeelServlet()
|
Method Summary | |
void |
doGet(javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response)
Receives an HTTP GET request from the protected service method and handles the request. |
void |
init(javax.servlet.ServletConfig config)
Initializes this servlet. |
Methods inherited from class javax.servlet.http.HttpServlet |
doDelete,
doOptions,
doPost,
doPut,
doTrace,
getLastModified,
service,
service |
Methods inherited from class javax.servlet.GenericServlet |
destroy,
getInitParameter,
getInitParameterNames,
getServletConfig,
getServletContext,
getServletInfo,
init,
log,
log |
Methods inherited from class java.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait |
Constructor Detail |
public LookAndFeelServlet()
Method Detail |
public void init(javax.servlet.ServletConfig config) throws javax.servlet.ServletException
The servlet engine calls this method once,
automatically, each time it loads the servlet. This
method is guaranteed to finish before the servlet accepts any
requests to its service
method. If a fatal
error occurs while the servlet is being initialized,
the servlet engine should throw
an UnavailableException
, rather than
calling the System.exit
method.
The init
method stores the
ServletConfig
object it receives from the servlet engine. If you override init
,
you should either call super.init
or store the ServletConfig
object in the new
init
method. If you decide to store the
ServletConfig
object in a different location,
you should also override the GenericServlet.getServletConfig()
method.
config
- the ServletConfig
object
that contains initialization parameters
for this servletUnavailableException
public void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, java.io.IOException
service
method and handles the request.
The GET method allows a client to read information
from the Web server, passing a query string appended
to an URL to tell the server what information
to return.
Overriding this method to support a GET request also automatically supports an HTTP HEAD request. A HEAD request is a GET request that returns no body in the response, only the request header fields.
If you override this method, you should read data from
the request, set entity headers in the response,
access the writer or output stream object, and finally,
write the response data. When you set headers, be
sure to include content type and encoding. If you use
a PrintWriter
object to return the response,
you must set the content type before you access the
PrintWriter
object.
The servlet engine must write the headers before the response data, because the headers can be flushed at any time after the data is written.
If you can set the Content-Length header (with the
javax.servlet.ServletResponse.#contentType
method),
the servlet
can use a persistent connection to return its response
to the client, improving performance dramatically.
If you cannot set Content-Length, you can sometimes avoid
the performance penalty if the response fits in an internal
buffer.
The GET method should be safe, that is, without any side effects for which users are held responsible. For example, most form queries have no side effects. If a client request is intended to change stored data, the request should use some other HTTP method.
The GET method should also be idempotent, meaning that it can be safely repeated. Sometimes making a method safe also makes it idempotent. For example, repeating queries is both safe and idempotent, but buying a product online or modifying data is neither safe nor idempotent.
If the request is incorrectly formatted, doGet
returns an HTTP BAD_REQUEST message.
req
- an HttpServletRequest
object that
contains the request the client has made
of the servletresp
- an HttpServletResponse
object that
contains the response the servlet sends
to the objectServletResponse.setContentType(java.lang.String)
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