javax.portlet
Interface PortletContext
public interface PortletContext
The
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.
java.lang.Object | getAttribute(java.lang.String name) - Returns the portlet container attribute with the given name,
or null if there is no attribute by that name.
|
java.util.Enumeration | getAttributeNames() - Returns an
Enumeration containing the attribute names
available within this portlet context, or an emtpy
Enumeration if no attributes are available.
|
java.lang.String | getInitParameter(java.lang.String name) - Returns a String containing the value of the named context-wide
initialization parameter, or
null if the parameter does not exist.
|
java.util.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.
|
java.net.URL | getResource(String path) - Returns a URL to the resource that is mapped to a specified
path.
|
java.io.InputStream | getResourceAsStream(String path) - Returns the resource located at the given path as an InputStream object.
|
java.util.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(java.lang.String msg) - Writes the specified message to a portlet log file, usually an event log.
|
void | log(java.lang.String message, java.lang.Throwable throwable) - Writes an explanatory message and a stack trace for a given
Throwable exception to the portlet log file.
|
void | removeAttribute(java.lang.String name) - Removes the attribute with the given name from the portlet context.
|
void | setAttribute(java.lang.String name, java.lang.Object object) - Binds an object to a given attribute name in this portlet context.
|
getAttribute
public java.lang.Object getAttribute(java.lang.String name)
Returns the portlet container attribute with the given name,
or null if there is no attribute by that name.
An attribute allows a portlet container to give the
portlet additional information not
already provided by this interface.
A list of supported attributes can be retrieved using
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.*
.
name
- a String
specifying the name
of the attribute
- an
Object
containing the value
of the attribute, or null
if no attribute exists matching the given
name
getAttributeNames
public java.util.Enumeration getAttributeNames()
Returns an
Enumeration
containing the attribute names
available within this portlet context, or an emtpy
Enumeration
if no attributes are available. Use the
getAttribute(String)
method with an attribute name
to get the value of an attribute.
- an
Enumeration
of attribute names
getInitParameter
public java.lang.String getInitParameter(java.lang.String name)
Returns a String containing the value of the named context-wide
initialization parameter, or null
if the parameter does not exist.
This method provides configuration information which may be useful for
an entire "portlet application".
name
- a String
containing the name of the
requested parameter
- a
String
containing the value
of the initialization parameter, or
null
if the parameter does not exist.
getInitParameterNames
public java.util.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.
- an
Enumeration
of String
objects containing the names of the context
initialization parameters
getMajorVersion
public int getMajorVersion()
Returns the major version of the Portlet API that this portlet
container supports.
getMimeType
public String getMimeType(String file)
Returns the MIME type of the specified file, or 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
.
file
- a String
specifying the name
of a file
- a
String
specifying the MIME type of the file
getMinorVersion
public int getMinorVersion()
Returns the minor version of the Portlet API that this portlet
container supports.
getNamedDispatcher
public PortletRequestDispatcher getNamedDispatcher(String name)
Returns a
PortletRequestDispatcher
object that acts
as a wrapper for the named servlet.
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.
name
- a String
specifying the name
of a servlet to be wrapped
- a
PortletRequestDispatcher
object
that acts as a wrapper for the named servlet
getPortletContextName
public 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.
- The name of the web application or null if no name has been declared in the deployment descriptor.
getRealPath
public String getRealPath(String path)
Returns a
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).
path
- a String
specifying a virtual path
- a
String
specifying the real path,
or null if the transformation cannot be performed.
getRequestDispatcher
public PortletRequestDispatcher getRequestDispatcher(String path)
Returns a
PortletRequestDispatcher
object that acts
as a wrapper for the resource located at the given path.
A
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.
path
- a String
specifying the pathname
to the resource
- a
PortletRequestDispatcher
object
that acts as a wrapper for the resource
at the specified path.
getResource
public java.net.URL getResource(String path)
throws java.net.MalformedURLException
Returns a URL to the resource that is mapped to a specified
path. The path must begin with a slash (
/
) 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.
path
- a String
specifying
the path to the resource
- the resource located at the named path,
or
null
if there is no resource
at that path
getResourceAsStream
public java.io.InputStream getResourceAsStream(String path)
Returns the resource located at the given path as an InputStream object.
The data in the InputStream can be of any type or length. The method returns
null if no resource exists at the given path.
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
).
path
- the path to the resource
getResourcePaths
public java.util.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. Paths indicating subdirectory paths
end with a slash (/
). 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/"}
.
path
- the partial path used to match the resources, which must start with a slash
- 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.
getServerInfo
public String getServerInfo()
Returns the name and version of the portlet container in which the
portlet is running.
The form of the returned string is
containername/versionnumber
.
- the string containing at least name and version number
log
public void log(java.lang.String msg)
Writes the specified message to a portlet log file, usually an event log.
The name and type of the portlet log file is specific to the portlet container.
This method mapps to the
ServletContext.log
method.
The portlet container may in addition log this message in a
portlet container specific log file.
msg
- a String
specifying the
message to be written to the log file
log
public void log(java.lang.String message,
java.lang.Throwable throwable)
Writes an explanatory message and a stack trace for a given
Throwable exception to the portlet log file.
The name and type of the portlet log file is specific to the
portlet container, usually an event log.
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.
message
- a String
that
describes the error or exceptionthrowable
- the Throwable
error
or exception
removeAttribute
public void removeAttribute(java.lang.String name)
Removes the attribute with the given name from the portlet context.
After removal, subsequent calls to
getAttribute(String)
to retrieve the attribute's value
will return
null
.
name
- a String
specifying the name
of the attribute to be removed
setAttribute
public void setAttribute(java.lang.String name,
java.lang.Object object)
Binds an object to a given attribute name in this portlet context.
If the name specified is already used for an attribute, this method
removes the old attribute and binds the name to the new attribute.
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.*
.
name
- a String
specifying the name
of the attributeobject
- an Object
representing the
attribute to be bound