javax.portlet
public interface PortletContext
PortletContext
interface defines a portlet view
of the portlet container.
The PortletContext
also makes resources available
to the portlet. Using the context, a portlet can access
the portlet log, and obtain URL references to resources.
There is one context per "portlet application" per Java Virtual Machine. (A
"portlet application" is a collection of portlets, servlets, and content installed
under a specific subset of the server URL namespace, such as /catalog
.
They are possibly installed via a .war
file.)
As a web application, a portlet application also has a servlet context.
The portlet context leverages most of its functionality from the
servlet context of the portlet application.
Attibutes stored in the context are global for all users and all components in the portlet application.
In the case of a web application marked "distributed" in its deployment descriptor, there will be one context instance for each virtual machine. In this situation, the context cannot be used as a location to share global information (because the information is not truly global). Use an external resource, such as a database to achieve sharing on a global scope.
Method Summary | |
---|---|
Object | getAttribute(String name)
Returns the portlet container attribute with the given name,
or null if there is no attribute by that name.
|
Enumeration | getAttributeNames()
Returns an Enumeration containing the attribute names
available within this portlet context, or an emtpy
Enumeration if no attributes are available. |
String | getInitParameter(String name)
Returns a String containing the value of the named context-wide
initialization parameter, or null if the parameter does not exist.
|
Enumeration | getInitParameterNames()
Returns the names of the context initialization parameters as an
Enumeration of String objects, or an empty Enumeration if the context
has no initialization parameters.
|
int | getMajorVersion()
Returns the major version of the Portlet API that this portlet
container supports.
|
String | getMimeType(String file)
Returns the MIME type of the specified file, or null if
the MIME type is not known. |
int | getMinorVersion()
Returns the minor version of the Portlet API that this portlet
container supports.
|
PortletRequestDispatcher | getNamedDispatcher(String name)
Returns a PortletRequestDispatcher object that acts
as a wrapper for the named servlet.
|
String | getPortletContextName()
Returns the name of this portlet application correponding to this PortletContext as specified
in the web.xml deployment descriptor for this web application by the
display-name element.
|
String | getRealPath(String path)
Returns a String containing the real path
for a given virtual path. |
PortletRequestDispatcher | getRequestDispatcher(String path)
Returns a PortletRequestDispatcher object that acts
as a wrapper for the resource located at the given path.
|
URL | getResource(String path)
Returns a URL to the resource that is mapped to a specified
path. |
InputStream | getResourceAsStream(String path)
Returns the resource located at the given path as an InputStream object.
|
Set | getResourcePaths(String path)
Returns a directory-like listing of all the paths to resources within
the web application longest sub-path of which
matches the supplied path argument. |
String | getServerInfo()
Returns the name and version of the portlet container in which the
portlet is running.
|
void | log(String msg)
Writes the specified message to a portlet log file, usually an event log.
|
void | log(String message, Throwable throwable)
Writes an explanatory message and a stack trace for a given
Throwable exception to the portlet log file.
|
void | removeAttribute(String name)
Removes the attribute with the given name from the portlet context.
|
void | setAttribute(String name, Object object)
Binds an object to a given attribute name in this portlet context.
|
getAttributeNames
.
The attribute is returned as a java.lang.Object
or some subclass.
Attribute names should follow the same convention as package
names. The Java Portlet API specification reserves names
matching java.*
, javax.*
,
and sun.*
.
Parameters: name a String
specifying the name
of the attribute
Returns: an Object
containing the value
of the attribute, or null
if no attribute exists matching the given
name
Throws: java.lang.IllegalArgumentException
if name is null
.
See Also: PortletContext
Enumeration
containing the attribute names
available within this portlet context, or an emtpy
Enumeration
if no attributes are available. Use the
PortletContext method with an attribute name
to get the value of an attribute.
Returns: an Enumeration
of attribute names
See Also: PortletContext
null
if the parameter does not exist.
This method provides configuration information which may be useful for
an entire "portlet application".
Parameters: name a String
containing the name of the
requested parameter
Returns: a String
containing the value
of the initialization parameter, or
null
if the parameter does not exist.
Throws: java.lang.IllegalArgumentException
if name is null
.
See Also: PortletContext
Enumeration
of String objects, or an empty Enumeration if the context
has no initialization parameters.
Returns: an Enumeration
of String
objects containing the names of the context
initialization parameters
See Also: PortletContext
Returns: the major version
See Also: getMinorVersion
null
if
the MIME type is not known. The MIME type is determined
by the configuration of the portlet container and may be specified
in a web application deployment descriptor. Common MIME
types are text/html
and image/gif
.
Parameters: file a String
specifying the name
of a file
Returns: a String
specifying the MIME type of the file
Returns: the minor version
See Also: getMajorVersion
Servlets (and also JSP pages) may be given names via server administration or via a web application deployment descriptor.
This method returns null
if the
PortletContext
cannot return a
PortletRequestDispatcher
for any reason.
Parameters: name a String
specifying the name
of a servlet to be wrapped
Returns: a PortletRequestDispatcher
object
that acts as a wrapper for the named servlet
web.xml
deployment descriptor for this web application by the
display-name
element.
Returns: The name of the web application or null if no name has been declared in the deployment descriptor.
String
containing the real path
for a given virtual path. For example, the path /index.html
returns the absolute file path of the portlet container file system.
The real path returned will be in a form
appropriate to the computer and operating system on
which the portlet container is running, including the
proper path separators. This method returns null
if the portlet container cannot translate the virtual path
to a real path for any reason (such as when the content is
being made available from a .war
archive).
Parameters: path a String
specifying a virtual path
Returns: a String
specifying the real path,
or null if the transformation cannot be performed.
PortletRequestDispatcher
object can be used include the
resource in a response. The resource can be dynamic or static.
The pathname must begin with a slash ( /
) and is interpreted as relative
to the current context root.
This method returns null
if the PortletContext
cannot return a PortletRequestDispatcher
for any reason.
Parameters: path a String
specifying the pathname
to the resource
Returns: a PortletRequestDispatcher
object
that acts as a wrapper for the resource
at the specified path.
See Also: PortletRequestDispatcher
/
) and is interpreted
as relative to the current context root.
This method allows the portlet container to make a resource
available to portlets from any source. Resources
can be located on a local or remote
file system, in a database, or in a .war
file.
The portlet container must implement the URL handlers
and URLConnection
objects that are necessary
to access the resource.
This method returns null
if no resource is mapped to the pathname.
Some containers may allow writing to the URL returned by this method using the methods of the URL class.
The resource content is returned directly, so be aware that
requesting a .jsp
page returns the JSP source code.
Use a RequestDispatcher
instead to include results of
an execution.
This method has a different purpose than
java.lang.Class.getResource
,
which looks up resources based on a class loader. This
method does not use class loaders.
Parameters: path a String
specifying
the path to the resource
Returns: the resource located at the named path,
or null
if there is no resource
at that path
Throws: MalformedURLException if the pathname is not given in the correct form
In order to access protected resources the path has to be prefixed with
/WEB-INF/
(for example /WEB-INF/myportlet/myportlet.jsp
).
Otherwise, the direct path is used
(for example /myportlet/myportlet.jsp
).
Parameters: path the path to the resource
Returns: the input stream
/
). The returned paths are all
relative to the root of the web application and have a leading slash.
For example, for a web application
containing
/welcome.html
/catalog/index.html
/catalog/products.html
/catalog/offers/books.html
/catalog/offers/music.html
/customer/login.jsp
/WEB-INF/web.xml
/WEB-INF/classes/com.acme.OrderPortlet.class,
getResourcePaths("/")
returns
{"/welcome.html", "/catalog/", "/customer/", "/WEB-INF/"}
getResourcePaths("/catalog/")
returns
{"/catalog/index.html", "/catalog/products.html", "/catalog/offers/"}
.Parameters: path the partial path used to match the resources, which must start with a slash
Returns: a Set containing the directory listing, or null
if there
are no resources in the web application of which the path
begins with the supplied path.
The form of the returned string is containername/versionnumber
.
Returns: the string containing at least name and version number
This method mapps to the ServletContext.log
method.
The portlet container may in addition log this message in a
portlet container specific log file.
Parameters: msg a String
specifying the
message to be written to the log file
This method is mapped to the ServletContext.log
method.
The portlet container may in addition log this message in a
portlet container specific log file.
Parameters: message a String
that
describes the error or exception throwable the Throwable
error
or exception
null
.
Parameters: name a String
specifying the name
of the attribute to be removed
Throws: java.lang.IllegalArgumentException
if name is null
.
If a null value is passed, the effect is the same as calling
removeAttribute()
.
Attribute names should follow the same convention as package
names. The Java Portlet API specification reserves names
matching java.*
, javax.*
, and
sun.*
.
Parameters: name a String
specifying the name
of the attribute object an Object
representing the
attribute to be bound
Throws: java.lang.IllegalArgumentException
if name is null
.