javax.servlet.ServletContext Maven / Gradle / Ivy
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package javax.servlet;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.EnumSet;
import java.util.Map;
import java.util.Set;
/**
* Defines a set of methods that a servlet uses to communicate with its
* servlet container, for example, to get the MIME type of a file, dispatch
* requests, or write to a log file.
*
* There is one context per "web application" per Java Virtual Machine. (A
* "web application" is a collection of servlets and content installed under a
* specific subset of the server's URL namespace such as /catalog
* and possibly installed via a .war file.)
*
*
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 won't be truly global). Use an external resource like
* a database instead.
*
*
The ServletContext object is contained within
* the {@link ServletConfig} object, which the Web server provides the
* servlet when the servlet is initialized.
*
* @author Various
*
* @see Servlet#getServletConfig
* @see ServletConfig#getServletContext
*/
public interface ServletContext {
/**
* The name of the ServletContext attribute which stores
* the private temporary directory (of type java.io.File)
* provided by the servlet container for the ServletContext
*/
public static final String TEMPDIR = "javax.servlet.context.tempdir";
/**
* Returns the context path of the web application.
*
*
The context path is the portion of the request URI that is used
* to select the context of the request. The context path always comes
* first in a request URI. The path starts with a / character
* but does not end with a / character. For servlets in the
* default (root) context, this method returns "".
*
*
It is possible that a servlet container may match a context by
* more than one context path. In such cases the
* {@link javax.servlet.http.HttpServletRequest#getContextPath()}
* will return the actual context path used by the request and it may
* differ from the path returned by this method.
* The context path returned by this method should be considered as the
* prime or preferred context path of the application.
*
* @return The context path of the web application, or "" for the
* default (root) context
*
* @see javax.servlet.http.HttpServletRequest#getContextPath()
*
* @since Servlet 2.5
*/
public String getContextPath();
/**
* Returns a ServletContext object that
* corresponds to a specified URL on the server.
*
*
This method allows servlets to gain
* access to the context for various parts of the server, and as
* needed obtain {@link RequestDispatcher} objects from the context.
* The given path must be begin with /, is interpreted relative
* to the server's document root and is matched against the context
* roots of other web applications hosted on this container.
*
*
In a security conscious environment, the servlet container may
* return null for a given URL.
*
* @param uripath a String specifying the context path of
* another web application in the container.
* @return the ServletContext object that
* corresponds to the named URL, or null if either
none exists or the container wishes to restrict
* this access.
*
* @see RequestDispatcher
*/
public ServletContext getContext(String uripath);
/**
* Returns the major version of the Java Servlet API that this
* servlet container supports. All implementations that comply
* with Version 3.0 must have this method return the integer 3.
*
* @return 3
*/
public int getMajorVersion();
/**
* Returns the minor version of the Servlet API that this
* servlet container supports. All implementations that comply
* with Version 3.0 must have this method return the integer 0.
*
* @return 0
*/
public int getMinorVersion();
/**
* 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 servlet container, and may be specified
* in a web application deployment descriptor. Common MIME
* types include text/html and image/gif.
*
* @param file a String specifying the name of a file
*
* @return a String specifying the file's MIME type
*/
public String getMimeType(String file);
/**
* Returns a directory-like listing of all the paths to resources
* within the web application whose longest sub-path matches the
* supplied path argument.
*
*
Paths indicating subdirectory paths end with a /.
*
*
The returned paths are all relative to the root of the web
* application, or relative to the /META-INF/resources
* directory of a JAR file inside the web application's
* /WEB-INF/lib directory, and have a leading /.
*
*
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.OrderServlet.class
* /WEB-INF/lib/catalog.jar!/META-INF/resources/catalog/moreOffers/books.html
* getResourcePaths(String path);
/**
* Returns a URL to the resource that is mapped to the given path.
*
* The path must begin with a / and is interpreted
* as relative to the current context root,
* or relative to the /META-INF/resources directory
* of a JAR file inside the web application's /WEB-INF/lib
* directory.
* This method will first search the document root of the
* web application for the requested resource, before searching
* any of the JAR files inside /WEB-INF/lib.
* The order in which the JAR files inside /WEB-INF/lib
* are searched is undefined.
*
*
This method allows the servlet container to make a resource
* available to servlets from any source. Resources
* can be located on a local or remote
* file system, in a database, or in a .war file.
*
*
The servlet 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.
*
* @param path a String specifying
* the path to the resource
*
* @return the resource located at the named path,
* or null if there is no resource at that path
*
* @exception MalformedURLException if the pathname is not given in
* the correct form
*/
public URL getResource(String path) throws MalformedURLException;
/**
* Returns the resource located at the named path as
* an InputStream object.
*
*
The data in the InputStream can be
* of any type or length. The path must be specified according
* to the rules given in getResource.
* This method returns null if no resource exists at
* the specified path.
*
*
Meta-information such as content length and content type
* that is available via getResource
* method is lost when using this method.
*
*
The servlet container must implement the URL handlers
* and URLConnection objects necessary to access
* the resource.
*
*
This method is different from
* java.lang.Class.getResourceAsStream,
* which uses a class loader. This method allows servlet containers
* to make a resource available
* to a servlet from any location, without using a class loader.
*
*
* @param path a String specifying the path
* to the resource
*
* @return the InputStream returned to the
* servlet, or null if no resource
* exists at the specified path
*/
public InputStream getResourceAsStream(String path);
/**
*
* Returns a {@link RequestDispatcher} object that acts
* as a wrapper for the resource located at the given path.
* A RequestDispatcher object can be used to forward
* a request to the resource or to include the resource in a response.
* The resource can be dynamic or static.
*
*
The pathname must begin with a / and is interpreted as
* relative to the current context root. Use getContext
* to obtain a RequestDispatcher for resources in foreign
* contexts.
*
*
This method returns null if the
* ServletContext cannot return a
* RequestDispatcher.
*
* @param path a String specifying the pathname
* to the resource
*
* @return a RequestDispatcher object
* that acts as a wrapper for the resource
* at the specified path, or null if
* the ServletContext cannot return
* a RequestDispatcher
*
* @see RequestDispatcher
* @see ServletContext#getContext
*/
public RequestDispatcher getRequestDispatcher(String path);
/**
* Returns a {@link RequestDispatcher} object that acts
* as a wrapper for the named servlet.
*
*
Servlets (and JSP pages also) may be given names via server
* administration or via a web application deployment descriptor.
* A servlet instance can determine its name using
* {@link ServletConfig#getServletName}.
*
*
This method returns null if the
* ServletContext
* cannot return a RequestDispatcher for any reason.
*
* @param name a String specifying the name
* of a servlet to wrap
*
* @return a RequestDispatcher object
* that acts as a wrapper for the named servlet,
* or null if the ServletContext
* cannot return a RequestDispatcher
*
* @see RequestDispatcher
* @see ServletContext#getContext
* @see ServletConfig#getServletName
*/
public RequestDispatcher getNamedDispatcher(String name);
/**
* @deprecated As of Java Servlet API 2.1, with no direct replacement.
*
*
This method was originally defined to retrieve a servlet
* from a ServletContext. In this version, this method
* always returns null and remains only to preserve
* binary compatibility. This method will be permanently removed
* in a future version of the Java Servlet API.
*
*
In lieu of this method, servlets can share information using the
* ServletContext class and can perform shared business logic
* by invoking methods on common non-servlet classes.
*/
public Servlet getServlet(String name) throws ServletException;
/**
* @deprecated As of Java Servlet API 2.0, with no replacement.
*
*
This method was originally defined to return an
* Enumeration of all the servlets known to this servlet
* context.
* In this version, this method always returns an empty enumeration and
* remains only to preserve binary compatibility. This method
* will be permanently removed in a future version of the Java
* Servlet API.
*/
public Enumeration getServlets();
/**
* @deprecated As of Java Servlet API 2.1, with no replacement.
*
* This method was originally defined to return an
* Enumeration
* of all the servlet names known to this context. In this version,
* this method always returns an empty Enumeration and
* remains only to preserve binary compatibility. This method will
* be permanently removed in a future version of the Java Servlet API.
*/
public Enumeration getServletNames();
/**
*
* Writes the specified message to a servlet log file, usually
* an event log. The name and type of the servlet log file is
* specific to the servlet container.
*
* @param msg a String specifying the
* message to be written to the log file
*/
public void log(String msg);
/**
* @deprecated As of Java Servlet API 2.1, use
* {@link #log(String message, Throwable throwable)}
* instead.
*
* This method was originally defined to write an
* exception's stack trace and an explanatory error message
* to the servlet log file.
*/
public void log(Exception exception, String msg);
/**
* Writes an explanatory message and a stack trace
* for a given Throwable exception
* to the servlet log file. The name and type of the servlet log
* file is specific to the servlet container, usually an event log.
*
* @param message a String that
* describes the error or exception
*
* @param throwable the Throwable error
* or exception
*/
public void log(String message, Throwable throwable);
/**
* Gets the real path corresponding to the given
* virtual path.
*
*
For example, if path is equal to /index.html,
* this method will return the absolute file path on the server's
* filesystem to which a request of the form
* http://<host>:<port>/<contextPath>/index.html
* would be mapped, where <contextPath> corresponds to the
* context path of this ServletContext.
*
*
The real path returned will be in a form
* appropriate to the computer and operating system on
* which the servlet container is running, including the
* proper path separators.
*
*
Resources inside the /META-INF/resources
* directories of JAR files bundled in the application's
* /WEB-INF/lib directory must be considered only if the
* container has unpacked them from their containing JAR file, in
* which case the path to the unpacked location must be returned.
*
*
This method returns null if the servlet container
* is unable to translate the given virtual path to a
* real path.
*
* @param path the virtual path to be translated to a
* real path
*
* @return the real path, or null if the
* translation cannot be performed
*/
public String getRealPath(String path);
/**
* Returns the name and version of the servlet container on which
* the servlet is running.
*
*
The form of the returned string is
* servername/versionnumber.
* For example, the JavaServer Web Development Kit may return the string
* JavaServer Web Dev Kit/1.0.
*
*
The servlet container may return other optional information
* after the primary string in parentheses, for example,
* JavaServer Web Dev Kit/1.0 (JDK 1.1.6; Windows NT 4.0 x86).
*
*
* @return a String containing at least the
* servlet container name and version number
*/
public String getServerInfo();
/**
* Returns a String containing the value of the named
* context-wide initialization parameter, or null if the
* parameter does not exist.
*
*
This method can make available configuration information useful
* to an entire web application. For example, it can provide a
* webmaster's email address or the name of a system that holds
* critical data.
*
* @param name a String containing the name of the
* parameter whose value is requested
*
* @return a String containing at least the
* servlet container name and version number
*
* @see ServletConfig#getInitParameter
*/
public String getInitParameter(String name);
/**
* Returns the names of the context's initialization parameters as an
* Enumeration of String objects, or an
* empty Enumeration if the context has no initialization
* parameters.
*
* @return an Enumeration of String
* objects containing the names of the context's
* initialization parameters
*
* @see ServletConfig#getInitParameter
*/
public Enumeration getInitParameterNames();
/**
* Sets the context initialization parameter with the given name and
* value on this ServletContext.
*
* @param name the name of the context initialization parameter to set
* @param value the value of the context initialization parameter to set
*
* @return true if the context initialization parameter with the given
* name and value was set successfully on this ServletContext, and false
* if it was not set because this ServletContext already contains a
* context initialization parameter with a matching name
* @throws IllegalStateException if this ServletContext has already
* been initialized
*
* @since Servlet 3.0
*/
public boolean setInitParameter(String name, String value);
/**
* Returns the servlet container attribute with the given name,
* or null if there is no attribute by that name.
*
* An attribute allows a servlet container to give the
* servlet additional information not
* already provided by this interface. See your
* server documentation for information about its attributes.
* 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 Servlet API specification reserves names
* matching java.*, javax.*,
* and sun.*.
*
* @param name a String specifying the name
* of the attribute
*
* @return an Object containing the value
* of the attribute, or null
* if no attribute exists matching the given
* name
*
* @see ServletContext#getAttributeNames
*/
public Object getAttribute(String name);
/**
* Returns an Enumeration containing the
* attribute names available within this ServletContext.
*
*
Use the {@link #getAttribute} method with an attribute name
* to get the value of an attribute.
*
* @return an Enumeration of attribute
* names
*
* @see #getAttribute
*/
public Enumeration getAttributeNames();
/**
* Binds an object to a given attribute name in this ServletContext. If
* the name specified is already used for an attribute, this
* method will replace the attribute with the new to the new attribute.
* If listeners are configured on the ServletContext the
* container notifies them accordingly.
*
* 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 Servlet API specification reserves names
* matching java.*, javax.*, and
* sun.*.
*
* @param name a String specifying the name
* of the attribute
*
* @param object an Object representing the
* attribute to be bound
*/
public void setAttribute(String name, Object object);
/**
* Removes the attribute with the given name from
* this ServletContext. After removal, subsequent calls to
* {@link #getAttribute} to retrieve the attribute's value
* will return null.
*
*
If listeners are configured on the ServletContext the
* container notifies them accordingly.
*
* @param name a String specifying the name
* of the attribute to be removed
*/
public void removeAttribute(String name);
/**
* Returns the name of this web application corresponding to this
* ServletContext as specified in the deployment descriptor for this
* web application by the display-name element.
*
* @return The name of the web application or null if no name has been
* declared in the deployment descriptor.
*
* @since Servlet 2.3
*/
public String getServletContextName();
/*
* Adds the servlet with the given name and class name to this servlet
* context.
*
*
The registered servlet may be further configured via the returned
* {@link ServletRegistration} object.
*
*
The specified className will be loaded using the
* classloader associated with the application represented by this
* ServletContext.
*
* @param servletName the name of the servlet
* @param className the fully qualified class name of the servlet
*
* @return a ServletRegistration object that may be used to further
* configure the registered servlet, or null if this
* ServletContext already contains a servlet with a matching name
* @throws IllegalStateException if this ServletContext has already
* been initialized
*
* @since Servlet 3.0
*/
public ServletRegistration.Dynamic addServlet(
String servletName, String className);
/*
* Registers the given servlet instance with this ServletContext
* under the given servletName.
*
*
The registered servlet may be further configured via the returned
* {@link ServletRegistration} object.
*
* @param servletName the name of the servlet
* @param servlet the servlet instance to register
*
* @return a ServletRegistration object that may be used to further
* configure the given servlet, or null if this
* ServletContext already contains a servlet with a matching name,
* or if the same servlet instance has already been registered with
* this or another ServletContext that is part of the same servlet
* container
* @throws IllegalStateException if this ServletContext has already
* been initialized
* @throws IllegalArgumentException if the given servlet instance
* implements {@link SingleThreadModel}
*
* @since Servlet 3.0
*/
public ServletRegistration.Dynamic addServlet(
String servletName, Servlet servlet);
/*
* Adds the servlet with the given name and class type to this servlet
* context.
*
*
The registered servlet may be further configured via the returned
* {@link ServletRegistration} object.
*
* @param servletName the name of the servlet
* @param servletClass the class object from which the servlet will be
* instantiated
*
* @return a ServletRegistration object that may be used to further
* configure the registered servlet, or null if this
* ServletContext already contains a servlet with a matching name
* @throws IllegalStateException if this ServletContext has already
* been initialized
*
* @since Servlet 3.0
*/
public ServletRegistration.Dynamic addServlet(String servletName,
Class servletClass);
/**
* Instantiates the given Servlet class and performs any required
* resource injection into the new Servlet instance before returning
* it.
*
*
The returned Servlet instance may be further customized before it
* is registered with this ServletContext via a call to
* {@link #addServlet(String,Servlet)}.
*
* @param c the Servlet class to instantiate
*
* @return the new Servlet instance
*
* @throws ServletException if an error occurs during the instantiation
* of, or resource injection into the new Servlet
*
* @since Servlet 3.0
*/
public T createServlet(Class c)
throws ServletException;
/**
* Gets the ServletRegistration corresponding to the servlet with the
* given servletName.
*
* @return the ServletRegistration corresponding to the servlet with the
* given servletName, or null if no ServletRegistration exists
* under that name in this ServletContext
*
* @since Servlet 3.0
*/
public ServletRegistration getServletRegistration(String servletName);
/**
* Gets an immutable (and possibly empty) Map of the ServletRegistration
* objects (keyed by servlet name) corresponding to all servlets
* registered with this ServletContext.
*
* The returned Map includes the ServletRegistration objects
* corresponding to all declared and annotated servlets, as well as the
* ServletRegistration objects corresponding to all servlets that have
* been added via one of the addServlet methods.
*
* @return Map of the ServletRegistration objects corresponding
* to all servlets currently registered with this ServletContext
*
* @since Servlet 3.0
*/
public Map getServletRegistrations();
/**
* Adds the filter with the given name and class name to this servlet
* context.
*
* The registered filter may be further configured via the returned
* {@link FilterRegistration} object.
*
*
The specified className will be loaded using the
* classloader associated with the application represented by this
* ServletContext.
*
* @param filterName the name of the filter
* @param className the fully qualified class name of the filter
*
* @return a FilterRegistration object that may be used to further
* configure the registered filter, or null if this
* ServletContext already contains a filter with a matching name
* @throws IllegalStateException if this ServletContext has already
* been initialized
*
* @since Servlet 3.0
*/
public FilterRegistration.Dynamic addFilter(
String filterName, String className);
/*
* Registers the given filter instance with this ServletContext
* under the given filterName.
*
*
The registered filter may be further configured via the returned
* {@link FilterRegistration} object.
*
* @param filterName the name of the filter
* @param filter the filter instance to register
*
* @return a FilterRegistration object that may be used to further
* configure the given filter, or null if this
* ServletContext already contains a filter with a matching name,
* or if the same filter instance has already been registered with
* this or another ServletContext that is part of the same servlet
* container
* @throws IllegalStateException if this ServletContext has already
* been initialized
*
* @since Servlet 3.0
*/
public FilterRegistration.Dynamic addFilter(
String filterName, Filter filter);
/**
* Adds the filter with the given name and class type to this servlet
* context.
*
*
The registered filter may be further configured via the returned
* {@link FilterRegistration} object.
*
* @param filterName the name of the filter
* @param filterClass the class object from which the filter will be
* instantiated
*
* @return a FilterRegistration object that may be used to further
* configure the registered filter, or null if this
* ServletContext already contains a filter with a matching name
* @throws IllegalStateException if this ServletContext has already
* been initialized
*
* @since Servlet 3.0
*/
public FilterRegistration.Dynamic addFilter(String filterName,
Class filterClass);
/**
* Instantiates the given Filter class and performs any required
* resource injection into the new Filter instance before returning
* it.
*
*
The returned Filter instance may be further customized before it
* is registered with this ServletContext via a call to
* {@link #addFilter(String,Filter)}.
*
* @param c the Filter class to instantiate
*
* @return the new Filter instance
*
* @throws ServletException if an error occurs during the instantiation
* of, or resource injection into the new Filter
*
* @since Servlet 3.0
*/
public T createFilter(Class c)
throws ServletException;
/**
* Gets the FilterRegistration corresponding to the filter with the
* given filterName.
*
* @return the FilterRegistration corresponding to the filter with the
* given filterName, or null if no FilterRegistration exists
* under that name in this ServletContext
*
* @since Servlet 3.0
*/
public FilterRegistration getFilterRegistration(String filterName);
/**
* Gets an immutable (and possibly empty) Map of the FilterRegistration
* objects (keyed by filter name) corresponding to all filters
* registered with this ServletContext.
*
* The returned Map includes the FilterRegistration objects
* corresponding to all declared and annotated filters, as well as the
* FilterRegistration objects corresponding to all filters that have
* been added via one of the addFilter methods.
*
* @return Map of the FilterRegistration objects corresponding
* to all filters currently registered with this ServletContext
*
* @since Servlet 3.0
*/
public Map getFilterRegistrations();
/**
* Gets the {@link SessionCookieConfig} object through which various
* properties of the session tracking cookies created on behalf of this
* ServletContext may be configured.
*
* Repeated invocations of this method will return the same
* SessionCookieConfig instance.
*
* @return the SessionCookieConfig object through which
* various properties of the session tracking cookies created on
* behalf of this ServletContext may be configured
*
* @since Servlet 3.0
*/
public SessionCookieConfig getSessionCookieConfig();
/**
* Sets the session tracking modes that are to become effective for this
* ServletContext.
*
*
The given sessionTrackingModes replaces any
* session tracking modes set by a previous invocation of this
* method on this ServletContext.
*
* @param sessionTrackingModes the set of session tracking modes to
* become effective for this ServletContext
*
* @throws IllegalStateException if this ServletContext has
* already been initialized
* @throws IllegalArgumentException if sessionTrackingModes
* specifies a combination of SessionTrackingMode.SSL with a
* session tracking mode other than SessionTrackingMode.SSL,
* or if sessionTrackingModes specifies a session tracking mode
* that is not supported by the servlet container
*
* @since Servlet 3.0
*/
public void setSessionTrackingModes(Set sessionTrackingModes);
/**
* Gets the session tracking modes that are supported by default for this
* ServletContext.
*
* @return set of the session tracking modes supported by default for
* this ServletContext
*
* @since Servlet 3.0
*/
public Set getDefaultSessionTrackingModes();
/**
* Gets the session tracking modes that are in effect for this
* ServletContext.
*
* The session tracking modes in effect are those provided to
* {@link #setSessionTrackingModes setSessionTrackingModes}.
*
*
By default, the session tracking modes returned by
* {@link #getDefaultSessionTrackingModes getDefaultSessionTrackingModes}
* are in effect.
*
* @return set of the session tracking modes in effect for this
* ServletContext
*
* @since Servlet 3.0
*/
public Set getEffectiveSessionTrackingModes();
}