javax.servlet.ServletContext Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package javax.servlet;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.EventListener;
import java.util.Map;
import java.util.Set;
import javax.servlet.descriptor.JspConfigDescriptor;
/**
* 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.
*
* @version $Rev: 901916 $ $Date: 2010-01-21 18:12:17 -0500 (Thu, 21 Jan 2010) $
* @see Servlet#getServletConfig
* @see ServletConfig#getServletContext
*/
public interface ServletContext {
/**
* @since Servlet 3.0
*/
String ORDERED_LIBS = "javax.servlet.context.orderedLibs";
/**
* @since Servlet 3.0
*/
String TEMPDIR = "javax.servlet.context.tempdir";
/**
* @return context path for this web app or "" for the / context
* @since Servlet 2.5
*/
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
*/
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
*/
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
*/
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 are "text/html" and "image/gif".
*
* @param file a String specifying the name
* of a file
* @return a String specifying the file's MIME type
*/
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 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,
*
* getResourcePaths("/") returns {"/welcome.html", "/catalog/", "/customer/", "/WEB-INF/"}
* getResourcePaths("/catalog/") returns {"/catalog/index.html", "/catalog/products.html", "/catalog/offers/"}.
*
* @param path the partial path used to match the resources,
* which must start with a /
* @return a Set containing the directory listing, or null if there are no resources in the web application whose path
* begins with the supplied path.
* @since Servlet 2.3
*/
Set getResourcePaths(String path);
/**
* Returns a URL to the resource that is mapped to a specified
* path. The path must begin with a "/" and is interpreted
* as relative to the current context root.
*
* 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
* @throws MalformedURLException if the pathname is not given in
* the correct form
*/
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
*/
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
*/
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
*/
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.
*/
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.
*/
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.
*/
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
*/
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.
*/
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
*/
void log(String message, Throwable throwable);
/**
* Returns a String containing the real path
* for a given virtual path. For example, the path "/index.html"
* returns the absolute file path on the server's filesystem would be
* served by a request for "http://host/contextPath/index.html",
* where contextPath is 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. This method returns null
* if the servlet 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).
*
* @param path a String specifying a virtual path
* @return a String specifying the real path,
* or null if the translation cannot be performed
*/
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
*/
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
*/
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
*/
Enumeration getInitParameterNames();
/**
* Set the init parameter if it is not already set.
*
* @param name of the init parameter to set
* @param value new value
* @return whether it was set
* @since 3.0
*/
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
*/
Object getAttribute(String name);
/**
* Returns an Enumeration containing the
* attribute names available
* within this servlet context. Use the
* {@link #getAttribute} method with an attribute name
* to get the value of an attribute.
*
* @return an Enumeration of attribute
* names
* @see #getAttribute
*/
Enumeration getAttributeNames();
/**
* Binds an object to a given attribute name in this servlet context. 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
*/
void setAttribute(String name, Object object);
/**
* Removes the attribute with the given name from
* the servlet context. 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
*/
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
*/
String getServletContextName();
/**
* Add the specified servlet to the context
*
* @param servletName servlet's name
* @param className class name of servlet
* @return ServletRegistration.Dynamic allowing configuration of the servlet
* @throws IllegalArgumentException duplicate servletName
* @throws IllegalStateException this method called after #initialize
* @since 3.0
*/
ServletRegistration.Dynamic addServlet(String servletName, String className) throws IllegalArgumentException, IllegalStateException;
/**
* Add the specified servlet to the context
*
* @param servletName servlet's name
* @param servlet servlet instance, perhaps created with createServlet
* @return ServletRegistration.Dynamic allowing configuration of the servlet
* @throws IllegalArgumentException duplicate servletName
* @throws IllegalStateException this method called after #initialize
* @since 3.0
*/
ServletRegistration.Dynamic addServlet(String servletName, Servlet servlet) throws IllegalArgumentException, IllegalStateException;
/**
* Add the specified servlet to the context
*
* @param servletName servlet's name
* @param clazz class of the servlet
* @return ServletRegistration.Dynamic allowing configuration of the servlet
* @throws IllegalArgumentException duplicate servletName
* @throws IllegalStateException this method called after #initialize
* @since 3.0
*/
ServletRegistration.Dynamic addServlet(String servletName, Class clazz) throws IllegalArgumentException, IllegalStateException;
/**
* Create a servlet with dependencies injected.
*
* @param clazz servlet class
* @return instantiated and injected servlet
* @throws ServletException if something goes wrong
* @since Servlet 3.0
*/
T createServlet(Class clazz) throws ServletException;
/**
* Fish out the servlet registration for a named servlet
*
* @param servletName name of the servlet you want to configure
* @return ServletRegistration for servlet you want
* @since 3.0
*/
ServletRegistration getServletRegistration(String servletName);
/**
* Fish out the servlet registration for a named servlet
*
* @return Map of name to ServletRegistration for all registered servlets
* @since 3.0
*/
Map getServletRegistrations();
/**
* Add a filter to this context
*
* @param filterName name of filter
* @param className class name of filter
* @return FilterRegistration.Dynamic allowing configuration of filter
* @throws IllegalArgumentException duplicate filter name
* @throws IllegalStateException if called after #initialise
* @since 3.0
*/
FilterRegistration.Dynamic addFilter(String filterName, String className) throws IllegalArgumentException, IllegalStateException;
/**
* Add a filter to this context
*
* @param filterName name of filter
* @param filter filter instance perhaps from createFilter method
* @return FilterRegistration.Dynamic allowing configuration of filter
* @throws IllegalArgumentException duplicate filter name
* @throws IllegalStateException if called after #initialise
* @since 3.0
*/
FilterRegistration.Dynamic addFilter(String filterName, Filter filter) throws IllegalArgumentException, IllegalStateException;
/**
* Add a filter to this context
*
* @param filterName name of filter
* @param filterClass filter class
* @return FilterRegistration.Dynamic allowing configuration of filter
* @throws IllegalArgumentException duplicate filter name
* @throws IllegalStateException if called after #initialise
* @since 3.0
*/
FilterRegistration.Dynamic addFilter(String filterName, Class filterClass) throws IllegalArgumentException, IllegalStateException;
/**
* Create a filter with dependencies injected.
*
* @param clazz filter class
* @return instantiated and injected filter
* @throws ServletException if something goes wrong
* @since Servlet 3.0
*/
T createFilter(Class clazz) throws ServletException;
/**
* Return the FilterRegistration corresponding to the named filter
* @param filterName Name of filter you want to configure
* @return FilterRegistration allowing configuration of filter
* @since 3.0
*/
FilterRegistration getFilterRegistration(String filterName);
/**
* Return a possibly empty immutable map of registrations for all filters.
* @return FilterRegistration allowing configuration of filter
* @since 3.0
*/
Map getFilterRegistrations();
/**
* Add a listener created from the specified class
* @param listenerClass class of listener to add
* @since Servlet 3.0
*/
void addListener(Class listenerClass);
/**
* Add a listener created from the specified class name
* @param className name of class of listener to add
* @since Servlet 3.0
*/
void addListener(String className);
/**
* add the listener instance
* @param t listener instance
* @param type of listener
* @since Servlet 3.0
*/
void addListener(T t);
/**
* create a fully initialized listener
* @param clazz listener class
* @param type of listener class
* @return fully initialized listener object
* @since Servlet 3.0
*/
T createListener(Class clazz) throws ServletException;
/**
* declare the roles used in the web app as argumnents to isUserInRole
* @param roleNames the role names used in the web app
* @since Servlet 3.0
*/
void declareRoles(String... roleNames);
/**
* @return configuration of session cookie
* @since 3.0
*/
SessionCookieConfig getSessionCookieConfig();
/**
* @param sessionTrackingModes enumset of SessionTrackingModes for this web app
* @since 3.0
*/
void setSessionTrackingModes(Set sessionTrackingModes);
/**
* @return the default session tracking modes
* @since 3.0
*/
Set getDefaultSessionTrackingModes();
/**
*
* @return the major version of the servlet spec the web app thinks it is using.
* @throws UnsupportedOperationException if this ServletContext was constructed in a way where the spec version cannot be determined.
* @since 3.0
*/
int getEffectiveMajorVersion() throws UnsupportedOperationException;
/**
*
* @return the minor version of the servlet spec the web app thinks it is using.
* @throws UnsupportedOperationException if this ServletContext was constructed in a way where the spec version cannot be determined.
* @since 3.0
*/
int getEffectiveMinorVersion() throws UnsupportedOperationException;
/**
* @return the actual session tracking modes. These will be the default ones unless they've been explicitly set.
* @since 3.0
*/
Set getEffectiveSessionTrackingModes();
/**
*
* @return the classloader for this web app
* @since 3.0
*/
ClassLoader getClassLoader();
/**
*
* @return jsp config aggregated from xml bits or null
* @since 3.0
*/
JspConfigDescriptor getJspConfigDescriptor ();
}