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package javax.servlet;

import java.io.*;
import java.util.*;

/**
 * Defines an object to provide client request information to a servlet.  The
 * servlet container creates a ServletRequest object and passes
 * it as an argument to the servlet's service method.
 *
 * 

A ServletRequest object provides data including * parameter name and values, attributes, and an input stream. * Interfaces that extend ServletRequest can provide * additional protocol-specific data (for example, HTTP data is * provided by {@link javax.servlet.http.HttpServletRequest}. * * @author Various * * @see javax.servlet.http.HttpServletRequest * */ public interface ServletRequest { /** * * Returns the value of the named attribute as an Object, * or null if no attribute of the given name exists. * *

Attributes can be set two ways. The servlet container may set * attributes to make available custom information about a request. * For example, for requests made using HTTPS, the attribute * javax.servlet.request.X509Certificate can be used to * retrieve information on the certificate of the client. Attributes * can also be set programatically using * {@link ServletRequest#setAttribute}. This allows information to be * embedded into a request before a {@link RequestDispatcher} call. * *

Attribute names should follow the same conventions as package * names. This 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 * the attribute does not exist * */ public Object getAttribute(String name); /** * Returns an Enumeration containing the * names of the attributes available to this request. * This method returns an empty Enumeration * if the request has no attributes available to it. * * * @return an Enumeration of strings * containing the names * of the request's attributes * */ public Enumeration getAttributeNames(); /** * Returns the name of the character encoding used in the body of this * request. This method returns null if the request * does not specify a character encoding * * * @return a String containing the name of * the character encoding, or null * if the request does not specify a character encoding * */ public String getCharacterEncoding(); /** * Overrides the name of the character encoding used in the body of this * request. This method must be called prior to reading request parameters * or reading input using getReader(). Otherwise, it has no effect. * * @param env String containing the name of * the character encoding. * @throws UnsupportedEncodingException if this * ServletRequest is still in a state where a * character encoding may be set, but the specified * encoding is invalid */ public void setCharacterEncoding(String env) throws UnsupportedEncodingException; /** * Returns the length, in bytes, of the request body * and made available by the input stream, or -1 if the * length is not known. For HTTP servlets, same as the value * of the CGI variable CONTENT_LENGTH. * * @return an integer containing the length of the * request body or -1 if the length is not known * */ public int getContentLength(); /** * Returns the MIME type of the body of the request, or * null if the type is not known. For HTTP servlets, * same as the value of the CGI variable CONTENT_TYPE. * * @return a String containing the name * of the MIME type of * the request, or null if the type is not known * */ public String getContentType(); /** * Retrieves the body of the request as binary data using * a {@link ServletInputStream}. Either this method or * {@link #getReader} may be called to read the body, not both. * * @return a {@link ServletInputStream} object containing * the body of the request * * @exception IllegalStateException if the {@link #getReader} method * has already been called for this request * * @exception IOException if an input or output exception occurred */ public ServletInputStream getInputStream() throws IOException; /** * Returns the value of a request parameter as a String, * or null if the parameter does not exist. Request parameters * are extra information sent with the request. For HTTP servlets, * parameters are contained in the query string or posted form data. * *

You should only use this method when you are sure the * parameter has only one value. If the parameter might have * more than one value, use {@link #getParameterValues}. * *

If you use this method with a multivalued * parameter, the value returned is equal to the first value * in the array returned by getParameterValues. * *

If the parameter data was sent in the request body, such as occurs * with an HTTP POST request, then reading the body directly via {@link * #getInputStream} or {@link #getReader} can interfere * with the execution of this method. * * @param name a String specifying the * name of the parameter * * @return a String representing the * single value of the parameter * * @see #getParameterValues */ public String getParameter(String name); /** * * Returns an Enumeration of String * objects containing the names of the parameters contained * in this request. If the request has * no parameters, the method returns an * empty Enumeration. * * @return an Enumeration of String * objects, each String containing * the name of a request parameter; or an * empty Enumeration if the * request has no parameters */ public Enumeration getParameterNames(); /** * Returns an array of String objects containing * all of the values the given request parameter has, or * null if the parameter does not exist. * *

If the parameter has a single value, the array has a length * of 1. * * @param name a String containing the name of * the parameter whose value is requested * * @return an array of String objects * containing the parameter's values * * @see #getParameter */ public String[] getParameterValues(String name); /** * Returns a java.util.Map of the parameters of this request. * *

Request parameters are extra information sent with the request. * For HTTP servlets, parameters are contained in the query string or * posted form data. * * @return an immutable java.util.Map containing parameter names as * keys and parameter values as map values. The keys in the parameter * map are of type String. The values in the parameter map are of type * String array. */ public Map getParameterMap(); /** * Returns the name and version of the protocol the request uses * in the form protocol/majorVersion.minorVersion, for * example, HTTP/1.1. For HTTP servlets, the value * returned is the same as the value of the CGI variable * SERVER_PROTOCOL. * * @return a String containing the protocol * name and version number */ public String getProtocol(); /** * Returns the name of the scheme used to make this request, * for example, * http, https, or ftp. * Different schemes have different rules for constructing URLs, * as noted in RFC 1738. * * @return a String containing the name * of the scheme used to make this request */ public String getScheme(); /** * Returns the host name of the server to which the request was sent. * It is the value of the part before ":" in the Host * header value, if any, or the resolved server name, or the server IP * address. * * @return a String containing the name * of the server */ public String getServerName(); /** * Returns the port number to which the request was sent. * It is the value of the part after ":" in the Host * header value, if any, or the server port where the client connection * was accepted on. * * @return an integer specifying the port number * */ public int getServerPort(); /** * Retrieves the body of the request as character data using * a BufferedReader. The reader translates the character * data according to the character encoding used on the body. * Either this method or {@link #getInputStream} may be called to read the * body, not both. * * * @return a BufferedReader * containing the body of the request * * @exception UnsupportedEncodingException if the character set encoding * used is not supported and the * text cannot be decoded * * @exception IllegalStateException if {@link #getInputStream} method * has been called on this request * * @exception IOException if an input or output exception occurred * * @see #getInputStream * */ public BufferedReader getReader() throws IOException; /** * Returns the Internet Protocol (IP) address of the client * or last proxy that sent the request. * For HTTP servlets, same as the value of the * CGI variable REMOTE_ADDR. * * @return a String containing the * IP address of the client that sent the request * */ public String getRemoteAddr(); /** * Returns the fully qualified name of the client * or the last proxy that sent the request. * If the engine cannot or chooses not to resolve the hostname * (to improve performance), this method returns the dotted-string form of * the IP address. For HTTP servlets, same as the value of the CGI variable * REMOTE_HOST. * * @return a String containing the fully * qualified name of the client * */ public String getRemoteHost(); /** * * Stores an attribute in this request. * Attributes are reset between requests. This method is most * often used in conjunction with {@link RequestDispatcher}. * *

Attribute names should follow the same conventions as * package names. Names beginning with java.*, * javax.*, and com.sun.*, are * reserved for use by Sun Microsystems. *
If the object passed in is null, the effect is the same as * calling {@link #removeAttribute}. *
It is warned that when the request is dispatched from the * servlet resides in a different web application by * RequestDispatcher, the object set by this method * may not be correctly retrieved in the caller servlet. * * * @param name a String specifying * the name of the attribute * * @param o the Object to be stored * */ public void setAttribute(String name, Object o); /** * * Removes an attribute from this request. This method is not * generally needed as attributes only persist as long as the request * is being handled. * *

Attribute names should follow the same conventions as * package names. Names beginning with java.*, * javax.*, and com.sun.*, are * reserved for use by Sun Microsystems. * * * @param name a String specifying * the name of the attribute to remove * */ public void removeAttribute(String name); /** * Returns the preferred Locale that the client will * accept content in, based on the Accept-Language header. * If the client request doesn't provide an Accept-Language header, * this method returns the default locale for the server. * * * @return the preferred Locale for the client */ public Locale getLocale(); /** * Returns an Enumeration of Locale objects * indicating, in decreasing order starting with the preferred locale, the * locales that are acceptable to the client based on the Accept-Language * header. * If the client request doesn't provide an Accept-Language header, * this method returns an Enumeration containing one * Locale, the default locale for the server. * * @return an Enumeration of preferred * Locale objects for the client */ public Enumeration getLocales(); /** * * Returns a boolean indicating whether this request was made using a * secure channel, such as HTTPS. * * * @return a boolean indicating if the request was made using a * secure channel * */ public boolean isSecure(); /** * * 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 specified may be relative, although it cannot extend * outside the current servlet context. If the path begins with * a "/" it is interpreted as relative to the current context root. * This method returns null if the servlet container * cannot return a RequestDispatcher. * *

The difference between this method and {@link * ServletContext#getRequestDispatcher} is that this method can take a * relative path. * * @param path a String specifying the pathname * to the resource. If it is relative, it must be * relative against the current servlet. * * @return a RequestDispatcher object * that acts as a wrapper for the resource * at the specified path, or null * if the servlet container cannot return a * RequestDispatcher * * @see RequestDispatcher * @see ServletContext#getRequestDispatcher */ public RequestDispatcher getRequestDispatcher(String path); /** * @deprecated As of Version 2.1 of the Java Servlet API, * use {@link ServletContext#getRealPath} instead. */ public String getRealPath(String path); /** * Returns the Internet Protocol (IP) source port of the client * or last proxy that sent the request. * * @return an integer specifying the port number * * @since Servlet 2.4 */ public int getRemotePort(); /** * Returns the host name of the Internet Protocol (IP) interface on * which the request was received. * * @return a String containing the host * name of the IP on which the request was received. * * @since Servlet 2.4 */ public String getLocalName(); /** * Returns the Internet Protocol (IP) address of the interface on * which the request was received. * * @return a String containing the * IP address on which the request was received. * * @since Servlet 2.4 * */ public String getLocalAddr(); /** * Returns the Internet Protocol (IP) port number of the interface * on which the request was received. * * @return an integer specifying the port number * * @since Servlet 2.4 */ public int getLocalPort(); /** * Gets the servlet context to which this ServletRequest was last * dispatched. * * @return the servlet context to which this ServletRequest was last * dispatched * * @since Servlet 3.0 */ public ServletContext getServletContext(); /** * Puts this request into asynchronous mode, and initializes its * {@link AsyncContext} with the original (unwrapped) ServletRequest * and ServletResponse objects. * *

Calling this method will cause committal of the associated * response to be delayed until {@link AsyncContext#complete} is * called on the returned {@link AsyncContext}, or the asynchronous * operation has timed out. * *

Calling {@link AsyncContext#hasOriginalRequestAndResponse()} on * the returned AsyncContext will return true. Any filters * invoked in the outbound direction after this request was put * into asynchronous mode may use this as an indication that any request * and/or response wrappers that they added during their inbound * invocation need not stay around for the duration of the asynchronous * operation, and therefore any of their associated resources may be * released. * *

This method clears the list of {@link AsyncListener} instances * (if any) that were registered with the AsyncContext returned by the * previous call to one of the startAsync methods, after calling each * AsyncListener at its {@link AsyncListener#onStartAsync onStartAsync} * method. * *

Subsequent invocations of this method, or its overloaded * variant, will return the same AsyncContext instance, reinitialized * as appropriate. * * @return the (re)initialized AsyncContext * * @throws IllegalStateException if this request is within the scope of * a filter or servlet that does not support asynchronous operations * (that is, {@link #isAsyncSupported} returns false), * or if this method is called again without any asynchronous dispatch * (resulting from one of the {@link AsyncContext#dispatch} methods), * is called outside the scope of any such dispatch, or is called again * within the scope of the same dispatch, or if the response has * already been closed * * @since Servlet 3.0 */ public AsyncContext startAsync() throws IllegalStateException; /** * Puts this request into asynchronous mode, and initializes its * {@link AsyncContext} with the given request and response objects. * *

The ServletRequest and ServletResponse arguments must be * the same instances, or instances of {@link ServletRequestWrapper} and * {@link ServletResponseWrapper} that wrap them, that were passed to the * {@link Servlet#service service} method of the Servlet or the * {@link Filter#doFilter doFilter} method of the Filter, respectively, * in whose scope this method is being called. * *

Calling this method will cause committal of the associated * response to be delayed until {@link AsyncContext#complete} is * called on the returned {@link AsyncContext}, or the asynchronous * operation has timed out. * *

Calling {@link AsyncContext#hasOriginalRequestAndResponse()} on * the returned AsyncContext will return false, * unless the passed in ServletRequest and ServletResponse arguments * are the original ones or do not carry any application-provided wrappers. * Any filters invoked in the outbound direction after this * request was put into asynchronous mode may use this as an indication * that some of the request and/or response wrappers that they added * during their inbound invocation may need to stay in place for * the duration of the asynchronous operation, and their associated * resources may not be released. * A ServletRequestWrapper applied during the inbound * invocation of a filter may be released by the outbound * invocation of the filter only if the given servletRequest, * which is used to initialize the AsyncContext and will be returned by * a call to {@link AsyncContext#getRequest()}, does not contain said * ServletRequestWrapper. The same holds true for ServletResponseWrapper * instances. * *

This method clears the list of {@link AsyncListener} instances * (if any) that were registered with the AsyncContext returned by the * previous call to one of the startAsync methods, after calling each * AsyncListener at its {@link AsyncListener#onStartAsync onStartAsync} * method. * *

Subsequent invocations of this method, or its zero-argument * variant, will return the same AsyncContext instance, reinitialized * as appropriate. If a call to this method is followed by a call to its * zero-argument variant, the specified (and possibly wrapped) request * and response objects will remain locked in on the returned * AsyncContext. * * @param servletRequest the ServletRequest used to initialize the * AsyncContext * @param servletResponse the ServletResponse used to initialize the * AsyncContext * * @return the (re)initialized AsyncContext * * @throws IllegalStateException if this request is within the scope of * a filter or servlet that does not support asynchronous operations * (that is, {@link #isAsyncSupported} returns false), * or if this method is called again without any asynchronous dispatch * (resulting from one of the {@link AsyncContext#dispatch} methods), * is called outside the scope of any such dispatch, or is called again * within the scope of the same dispatch, or if the response has * already been closed * * @since Servlet 3.0 */ public AsyncContext startAsync(ServletRequest servletRequest, ServletResponse servletResponse) throws IllegalStateException; /** * Checks if this request has been put into asynchronous mode. * *

A ServletRequest is put into asynchronous mode by calling * {@link #startAsync} or * {@link #startAsync(ServletRequest,ServletResponse)} on it. * *

This method returns false if this request was * put into asynchronous mode, but has since been dispatched using * one of the {@link AsyncContext#dispatch} methods or released * from asynchronous mode via a call to {@link AsyncContext#complete}. * * @return true if this request has been put into asynchronous mode, * false otherwise * * @since Servlet 3.0 */ public boolean isAsyncStarted(); /** * Checks if this request supports asynchronous operation. * *

Asynchronous operation is disabled for this request if this request * is within the scope of a filter or servlet that has not been annotated * or flagged in the deployment descriptor as being able to support * asynchronous handling. * * @return true if this request supports asynchronous operation, false * otherwise * * @since Servlet 3.0 */ public boolean isAsyncSupported(); /** * Gets the AsyncContext that was created or reinitialized by the * most recent invocation of {@link #startAsync} or * {@link #startAsync(ServletRequest,ServletResponse)} on this request. * * @return the AsyncContext that was created or reinitialized by the * most recent invocation of {@link #startAsync} or * {@link #startAsync(ServletRequest,ServletResponse)} on * this request * * @throws IllegalStateException if this request has not been put * into asynchronous mode, i.e., if neither {@link #startAsync} nor * {@link #startAsync(ServletRequest,ServletResponse)} has been called * * @since Servlet 3.0 */ public AsyncContext getAsyncContext(); /** * Gets the dispatcher type of this request. * *

The dispatcher type of a request is used by the container * to select the filters that need to be applied to the request: * Only filters with matching dispatcher type and url patterns will * be applied. * *

Allowing a filter that has been configured for multiple * dispatcher types to query a request for its dispatcher type * allows the filter to process the request differently depending on * its dispatcher type. * *

The initial dispatcher type of a request is defined as * DispatcherType.REQUEST. The dispatcher type of a request * dispatched via {@link RequestDispatcher#forward(ServletRequest, * ServletResponse)} or {@link RequestDispatcher#include(ServletRequest, * ServletResponse)} is given as DispatcherType.FORWARD or * DispatcherType.INCLUDE, respectively, while the * dispatcher type of an asynchronous request dispatched via * one of the {@link AsyncContext#dispatch} methods is given as * DispatcherType.ASYNC. Finally, the dispatcher type of a * request dispatched to an error page by the container's error handling * mechanism is given as DispatcherType.ERROR. * * @return the dispatcher type of this request * * @see DispatcherType * * @since Servlet 3.0 */ public DispatcherType getDispatcherType(); }





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