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.

Version:

$Revision: 5441 $

Author:

Julien Viet

Method Summary

Modifier and Type	Method and Description
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 msg, 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.

Method Detail

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

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.

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

getNamedDispatcher

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.

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

See Also:

PortletRequestDispatcher

getResourceAsStream

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).

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()

getMinorVersion

int getMinorVersion()

Returns the minor version of the Portlet API that this portlet container supports.

Returns:

the minor version

See Also:

getMajorVersion()

getMimeType

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.

Parameters:

file - a String specifying the name of a file

Returns:

a String specifying the MIME type of the file

getRealPath

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).

Parameters:

path - a String specifying a virtual path

Returns:

a String specifying the real path, or null if the transformation cannot be performed.

getResourcePaths

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/"}.

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

URL getResource(String path)
         throws 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.

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

getAttribute

Object getAttribute(String name)
             throws IllegalArgumentException

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.*.

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:

IllegalArgumentException - if name is null.

See Also:

getAttributeNames()

getAttributeNames

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(java.lang.String) method with an attribute name to get the value of an attribute.

Returns:

an Enumeration of attribute names

See Also:

getAttribute(java.lang.String)

getInitParameter

String getInitParameter(String name)
                 throws IllegalArgumentException

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".

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:

IllegalArgumentException - if name is null.

See Also:

getInitParameterNames()

getInitParameterNames

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.

Returns:

an Enumeration of String objects containing the names of the context initialization parameters

See Also:

getInitParameter(java.lang.String)

log

void log(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.

Parameters:

msg - a String specifying the message to be written to the log file

log

void log(String msg,
         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.

Parameters:

msg - a String that describes the error or exception

throwable - the Throwable error or exception

removeAttribute

void removeAttribute(String name)
              throws IllegalArgumentException

Removes the attribute with the given name from the portlet context. After removal, subsequent calls to getAttribute(java.lang.String) to retrieve the attribute's value will return null.

Parameters:

name - a String specifying the name of the attribute to be removed

Throws:

IllegalArgumentException - if name is null.

setAttribute

void setAttribute(String name,
                  Object object)
           throws IllegalArgumentException

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.*.

Parameters:

name - a String specifying the name of the attribute

object - an Object representing the attribute to be bound

Throws:

IllegalArgumentException - if name is null.

getPortletContextName

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.

Returns:

The name of the web application or null if no name has been declared in the deployment descriptor.