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Interface javax.servlet.ServletContext

public interface ServletContext

In a server that supports the concept of multiple hosts (and even virtual hosts), the context must be at least as unique as the host. Servlet engines may also provide context objects that are unique to a group of servlets and which is tied to a specific portion of the URL path namespace of the host. This grouping may be administratively assigned or defined by deployment information.

Servlets get the ServletContext object via the getServletContext method of ServletConfig. The ServletConfig object is provided to the servlet at initialization, and is accessible via the servlet's getServletConfig method.

See Also:

getServletConfig, getServletContext

getAttribute(String)

Returns the value of the named attribute of the network service, or null if the attribute does not exist.

getAttributeNames()

Returns an enumeration of the attribute names present in the network service.

getContext(String)

Returns the ServletContext object for a particular uripath, or null if there is not a ServletContext for the particular path available or visible to this servlet.

getMajorVersion()

Returns the major version of the servlet API that this context supports.

getMimeType(String)

Returns the mime type of the specified file, or null if not known.

getMinorVersion()

Returns the minor version of the servlet API that this context supports.

getRealPath(String)

Applies alias rules to the specified virtual path and returns the corresponding real path.

getRequestDispatcher(String)

Returns a request dispatcher to a server component accessible via a URL path.

getResource(String)

Returns a URL object allowing access to any content resource requested.

getResourceAsStream(String)

Returns an input stream to the given content resource path, or null if not found.

getServerInfo()

Returns the name and version of the network service under which the servlet is running.

getServlet(String)

This method has been deprecated and only remains to preserve binary compatibility. Deprecated.

getServletNames()

This method has been deprecated and only remains to preserve binary compatibility. Deprecated.

getServlets()

This method has been deprecated and only remains to preserve binary compatibility. Deprecated.

log(Exception, String)

Write the stacktrace and the given message string to the servlet log file. Deprecated.

log(String)

Writes the given message string to the servlet log file.

log(String, Throwable)

Write the given message and stacktrace to the servlet log.

removeAttribute(String)

Removes the attribute from the context that is bound to a particular name.

setAttribute(String, Object)

This method stores an attribute in the servlet context.

 public abstract ServletContext getContext(String uripath)

Returns the ServletContext object for a particular uripath, or null if there is not a ServletContext for the particular path available or visible to this servlet. This allows one content to get RequestDispatchers and resources from another context if so permitted. In more restricted environments, this call may return null.

 public abstract int getMajorVersion()

Returns the major version of the servlet API that this context supports.

Returns:

2

 public abstract String getMimeType(String file)

Returns the mime type of the specified file, or null if not known.

Parameters:

file - name of the file whose mime type is required

 public abstract int getMinorVersion()

Returns the minor version of the servlet API that this context supports.

Returns:

1

 public abstract URL getResource(String path) throws MalformedURLException

Returns a URL object allowing access to any content resource requested. This method allows a servlet to access items in the host servlet engine's document space in a system independent way whether they reside on the local file system, a remote file system, a database, or a remote network site without knowing the specific details of how to obtain the resources. The servlet engine must implement all of the specifics about how to access the resource.

Only content resources known to this context object can be accessed via this call.

The path parameter of this call must be a URL path. To access the file index.html in the server's document root, the call to this method would have the parameter "/index.html".

Parameters:

path - Path of the content resource

Throws: MalformedURLException

if the resource path is not properly formed.

 public abstract InputStream getResourceAsStream(String path)

Returns an input stream to the given content resource path, or null if not found.

 public abstract RequestDispatcher getRequestDispatcher(String urlpath)

Returns a request dispatcher to a server component accessible via a URL path. This method is typically used to obtain a reference to another servlet. After obtaining a RequestDispatcher, the servlet programmer forward a request to the target component or include content from it.

This method will return null if the context cannot provide a dispatcher for the path provided.

Parameters:

urlpath - Path to use to look up the target server resource

See Also:

RequestDispatcher

 public abstract Servlet getServlet(String name) throws ServletException

Note: getServlet() is deprecated. This method has been deprecated for security and servlet lifecycle reasons. This method will be permanently removed in a future version of the Servlet API.

This method has been deprecated and only remains to preserve binary compatibility. This method will always return null.

 public abstract Enumeration getServlets()

Note: getServlets() is deprecated. This method has been deprecated for security and servlet lifecycle reasons. This method will be permanently removed in a future version of the Servlet API.

This method has been deprecated and only remains to preserve binary compatibility. This method must always return an empty enumeration.

 public abstract Enumeration getServletNames()

Note: getServletNames() is deprecated. This method has been deprecated for security and servlet lifecycle reasons. This method will be permanently removed in a future version of the Servlet API.

This method has been deprecated and only remains to preserve binary compatibility. This methd must always return an empty enumeration.

 public abstract void log(String msg)

Writes the given message string to the servlet log file. The name and type of the servlet log file is server specific; it is normally an event log.

Parameters:

msg - the message to be written

 public abstract void log(Exception exception,
                          String msg)

Note: log() is deprecated. Use log(String message, Throwable t) instead

Write the stacktrace and the given message string to the servlet log file. The name of the servlet log file is server specific; it is normally an event log.

Parameters:

exception - the exception to be written

msg - the message to be written

 public abstract void log(String message,
                          Throwable throwable)

Write the given message and stacktrace to the servlet log. The name of the log is network service specific; it is typically the event log.

Parameters:

msg - the message to be written

throwable - the exception to be written

 public abstract String getRealPath(String path)

Applies alias rules to the specified virtual path and returns the corresponding real path. For example, in an HTTP servlet, this method would resolve the path against the HTTP service's docroot. Returns null if virtual paths are not supported, or if the translation could not be performed for any reason.

Parameters:

path - the virtual path to be translated into a real path

 public abstract String getServerInfo()

Returns the name and version of the network service under which the servlet is running. For example, if the network service was an HTTP service, then this would be the same as the CGI variable SERVER_SOFTWARE.

 public abstract Object getAttribute(String name)

Returns the value of the named attribute of the network service, or null if the attribute does not exist. This method allows access to additional information about the service, not already provided by the other methods in this interface. Attribute names should follow the same convention as package names. The package names java.* and javax.* are reserved for use by Javasoft, and com.sun.* is reserved for use by Sun Microsystems.

Parameters:

name - the name of the attribute whose value is required

Returns:

the value of the attribute, or null if the attribute does not exist.

 public abstract Enumeration getAttributeNames()

Returns an enumeration of the attribute names present in the network service.

 public abstract void setAttribute(String name,
                                   Object object)

This method stores an attribute in the servlet context.

Parameters:

name - the name of the attribute to store

value - the value of the attribute

 public abstract void removeAttribute(String name)

Removes the attribute from the context that is bound to a particular name.

Parameters:

name - the name of the attribute to remove from the context

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