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
Modifier and TypeMethodDescriptiongetAttribute
(String name) Returns the portlet container attribute with the given name, or null if there is no attribute by that name.Returns anEnumeration
containing the attribute names available within this portlet context, or an emtpyEnumeration
if no attributes are available.getInitParameter
(String name) Returns a String containing the value of the named context-wide initialization parameter, ornull
if the parameter does not exist.Returns the names of the context initialization parameters as anEnumeration
of String objects, or an empty Enumeration if the context has no initialization parameters.int
Returns the major version of the Portlet API that this portlet container supports.getMimeType
(String file) Returns the MIME type of the specified file, ornull
if the MIME type is not known.int
Returns the minor version of the Portlet API that this portlet container supports.getNamedDispatcher
(String name) Returns aPortletRequestDispatcher
object that acts as a wrapper for the named servlet.Returns the name of this portlet application correponding to this PortletContext as specified in theweb.xml
deployment descriptor for this web application by thedisplay-name
element.getRealPath
(String path) Returns aString
containing the real path for a given virtual path.getRequestDispatcher
(String path) Returns aPortletRequestDispatcher
object that acts as a wrapper for the resource located at the given path.getResource
(String path) Returns a URL to the resource that is mapped to a specified path.getResourceAsStream
(String path) Returns the resource located at the given path as an InputStream object.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.Returns the name and version of the portlet container in which the portlet is running.void
Writes the specified message to a portlet log file, usually an event log.void
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.
-
Method Details
-
getServerInfo
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
.- Returns:
- the string containing at least name and version number
-
getRequestDispatcher
Returns aPortletRequestDispatcher
object that acts as a wrapper for the resource located at the given path. APortletRequestDispatcher
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 thePortletContext
cannot return aPortletRequestDispatcher
for any reason.- Parameters:
path
- aString
specifying the pathname to the resource- Returns:
- a
PortletRequestDispatcher
object that acts as a wrapper for the resource at the specified path. - See Also:
-
getNamedDispatcher
Returns aPortletRequestDispatcher
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 thePortletContext
cannot return aPortletRequestDispatcher
for any reason.- Parameters:
name
- aString
specifying the name of a servlet to be wrapped- Returns:
- a
PortletRequestDispatcher
object that acts as a wrapper for the named servlet - See Also:
-
getResourceAsStream
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
).- Parameters:
path
- the path to the resource- Returns:
- the input stream
-
getMajorVersion
int getMajorVersion()Returns the major version of the Portlet API that this portlet container supports.- Returns:
- the major version
- See Also:
-
getMinorVersion
int getMinorVersion()Returns the minor version of the Portlet API that this portlet container supports.- Returns:
- the minor version
- See Also:
-
getMimeType
Returns the MIME type of the specified file, ornull
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 aretext/html
andimage/gif
.- Parameters:
file
- aString
specifying the name of a file- Returns:
- a
String
specifying the MIME type of the file
-
getRealPath
Returns aString
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
- aString
specifying a virtual path- Returns:
- a
String
specifying the real path, or null if the transformation cannot be performed.
-
getResourcePaths
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/"}
.- 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.
-
getResource
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 aRequestDispatcher
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
- aString
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 formMalformedURLException
-
getAttribute
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 usinggetAttributeNames
.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 matchingjava.*
,javax.*
, andsun.*
.- Parameters:
name
- aString
specifying the name of the attribute- Returns:
- an
Object
containing the value of the attribute, ornull
if no attribute exists matching the given name - Throws:
IllegalArgumentException
- if name isnull
.- See Also:
-
getAttributeNames
Enumeration getAttributeNames()Returns anEnumeration
containing the attribute names available within this portlet context, or an emtpyEnumeration
if no attributes are available. Use thegetAttribute(java.lang.String)
method with an attribute name to get the value of an attribute.- Returns:
- an
Enumeration
of attribute names - See Also:
-
getInitParameter
Returns a String containing the value of the named context-wide initialization parameter, ornull
if the parameter does not exist. This method provides configuration information which may be useful for an entire "portlet application".- Parameters:
name
- aString
containing the name of the requested parameter- Returns:
- a
String
containing the value of the initialization parameter, ornull
if the parameter does not exist. - Throws:
IllegalArgumentException
- if name isnull
.- See Also:
-
getInitParameterNames
Enumeration getInitParameterNames()Returns the names of the context initialization parameters as anEnumeration
of String objects, or an empty Enumeration if the context has no initialization parameters.- Returns:
- an
Enumeration
ofString
objects containing the names of the context initialization parameters - See Also:
-
log
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.- Parameters:
msg
- aString
specifying the message to be written to the log file
-
log
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.- Parameters:
message
- aString
that describes the error or exceptionthrowable
- theThrowable
error or exception
-
removeAttribute
Removes the attribute with the given name from the portlet context. After removal, subsequent calls togetAttribute(java.lang.String)
to retrieve the attribute's value will returnnull
.- Parameters:
name
- aString
specifying the name of the attribute to be removed- Throws:
IllegalArgumentException
- if name isnull
.
-
setAttribute
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.*
, andsun.*
.- Parameters:
name
- aString
specifying the name of the attributeobject
- anObject
representing the attribute to be bound- Throws:
IllegalArgumentException
- if name isnull
.
-
getPortletContextName
String getPortletContextName()Returns the name of this portlet application correponding to this PortletContext as specified in theweb.xml
deployment descriptor for this web application by thedisplay-name
element.- Returns:
- The name of the web application or null if no name has been declared in the deployment descriptor.
-