HttpServletResponse.java
/*
* 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 jakarta.servlet.http;
import java.io.IOException;
import java.util.Collection;
import java.util.Map;
import java.util.function.Supplier;
import jakarta.servlet.ServletResponse;
/**
* Extends the {@link ServletResponse} interface to provide HTTP-specific functionality in sending a response. For
* example, it has methods to access HTTP headers and cookies.
* <p>
* The servlet container creates an <code>HttpServletResponse</code> object and passes it as an argument to the
* servlet's service methods (<code>doGet</code>, <code>doPost</code>, etc).
*
* @see jakarta.servlet.ServletResponse
*/
public interface HttpServletResponse extends ServletResponse {
/**
* Adds the specified cookie to the response. This method can be called multiple times to set more than one cookie.
*
* @param cookie the Cookie to return to the client
*/
void addCookie(Cookie cookie);
/**
* Returns a boolean indicating whether the named response header has already been set.
*
* @param name the header name
*
* @return <code>true</code> if the named response header has already been set; <code>false</code> otherwise
*/
boolean containsHeader(String name);
/**
* Encodes the specified URL by including the session ID in it, or, if encoding is not needed, returns the URL
* unchanged. The implementation of this method includes the logic to determine whether the session ID needs to be
* encoded in the URL. For example, if the browser supports cookies, or session tracking is turned off, URL encoding
* is unnecessary.
* <p>
* For robust session tracking, all URLs emitted by a servlet should be run through this method. Otherwise, URL
* rewriting cannot be used with browsers which do not support cookies.
*
* @param url the url to be encoded.
*
* @return the encoded URL if encoding is needed; the unchanged URL otherwise.
*/
String encodeURL(String url);
/**
* Encodes the specified URL for use in the <code>sendRedirect</code> method or, if encoding is not needed, returns
* the URL unchanged. The implementation of this method includes the logic to determine whether the session ID needs
* to be encoded in the URL. Because the rules for making this determination can differ from those used to decide
* whether to encode a normal link, this method is separated from the <code>encodeURL</code> method.
* <p>
* All URLs sent to the <code>HttpServletResponse.sendRedirect</code> method should be run through this method.
* Otherwise, URL rewriting cannot be used with browsers which do not support cookies.
*
* @param url the url to be encoded.
*
* @return the encoded URL if encoding is needed; the unchanged URL otherwise.
*
* @see #sendRedirect
*/
String encodeRedirectURL(String url);
/**
* Sends an error response to the client using the specified status code and clears the output buffer. The server
* defaults to creating the response to look like an HTML-formatted server error page containing the specified
* message, setting the content type to "text/html", leaving cookies and other headers unmodified. If an error-page
* declaration has been made for the web application corresponding to the status code passed in, it will be served
* back in preference to the suggested msg parameter.
* <p>
* If the response has already been committed, this method throws an IllegalStateException. After using this method,
* the response should be considered to be committed and should not be written to.
*
* @param sc the error status code
* @param msg the descriptive message
*
* @exception IOException If an input or output exception occurs
* @exception IllegalStateException If the response was committed
*/
void sendError(int sc, String msg) throws IOException;
/**
* Sends an error response to the client using the specified status code and clears the buffer. This is equivalent
* to calling {@link #sendError(int, String)} with the same status code and <code>null</code> for the message.
*
* @param sc the error status code
*
* @exception IOException If an input or output exception occurs
* @exception IllegalStateException If the response was committed before this method call
*/
void sendError(int sc) throws IOException;
/**
* Sends a redirect response to the client using the specified redirect location URL with the status code
* {@link #SC_FOUND} 302 (Found), clears the response buffer and commits the response. The response buffer will be
* replaced with a short hypertext note as per RFC 9110.
* <p>
* This method has no effect if called from an include.
*
* @param location the redirect location URL (may be absolute or relative)
*
* @exception IOException If an input or output exception occurs
* @exception IllegalArgumentException If a relative URL is given and cannot be converted into an absolute URL
* @exception IllegalStateException If the response was already committed when this method was called
*
* @see #sendRedirect(String, int, boolean)
*/
default void sendRedirect(String location) throws IOException {
sendRedirect(location, SC_FOUND, true);
}
/**
* Sends a redirect response to the client using the specified redirect location URL with the status code
* {@link #SC_FOUND} 302 (Found), optionally clears the response buffer and commits the response. If the response
* buffer is cleared, it will be replaced with a short hypertext note as per RFC 9110.
* <p>
* This method has no effect if called from an include.
*
* @param location the redirect location URL (may be absolute or relative)
* @param clearBuffer if {@code true}, clear the buffer and replace it with the data set by this method otherwise
* retain the existing buffer
*
* @exception IOException If an input or output exception occurs
* @exception IllegalArgumentException If a relative URL is given and cannot be converted into an absolute URL
* @exception IllegalStateException If the response was already committed when this method was called
*
* @see #sendRedirect(String, int, boolean)
*
* @since Servlet 6.1
*/
default void sendRedirect(String location, boolean clearBuffer) throws IOException {
sendRedirect(location, SC_FOUND, clearBuffer);
}
/**
* Sends a redirect response to the client using the specified redirect location URL and status code, clears the
* response buffer and commits the response. The response buffer will be replaced with a short hypertext note as per
* RFC 9110.
* <p>
* This method has no effect if called from an include.
*
* @param location the redirect location URL (may be absolute or relative)
* @param sc the status code to use for the redirect
*
* @exception IOException If an input or output exception occurs
* @exception IllegalArgumentException If a relative URL is given and cannot be converted into an absolute URL
* @exception IllegalStateException If the response was already committed when this method was called
*
* @see #sendRedirect(String, int, boolean)
*
* @since Servlet 6.1
*/
default void sendRedirect(String location, int sc) throws IOException {
sendRedirect(location, sc, true);
}
/**
* Sends a redirect response to the client using the specified redirect location URL and status code, optionally
* clears the response buffer and commits the response. If the response buffer is cleared, it will be replaced with
* a short hypertext note as per RFC 9110.
* <p>
* This method has no effect if called from an include.
* <p>
* This method accepts both relative and absolute URLs. Absolute URLs passed to this method are used as provided as
* the redirect location URL. Relative URLs are converted to absolute URLs unless a container specific
* feature/option is provided that controls whether relative URLs passed to this method are converted to absolute
* URLs or used as provided for the redirect location URL. If converting a relative URL to an absolute URL then:
* <ul>
* <li>If the location is relative without a leading '/' the container interprets it as relative to the current
* request URI.</li>
* <li>If the location is relative with a leading '/' the container interprets it as relative to the servlet
* container root.</li>
* <li>If the location is relative with two leading '/' the container interprets it as a network-path reference (see
* <a href="http://www.ietf.org/rfc/rfc3986.txt"> RFC 3986: Uniform Resource Identifier (URI): Generic Syntax</a>,
* section 4.2 "Relative Reference").</li>
* </ul>
* <p>
* If the response has already been committed, this method throws an IllegalStateException. After using this method,
* the response should be considered to be committed and should not be written to.
*
* @param location the redirect location URL (may be absolute or relative)
* @param sc the status code to use for the redirect
* @param clearBuffer if {@code true}, clear the buffer and replace it with the data set by this method otherwise
* retain the existing buffer
*
* @exception IOException If an input or output exception occurs
* @exception IllegalArgumentException If a relative URL is given and cannot be converted into an absolute URL
* @exception IllegalStateException If the response was already committed when this method was called
*
* @since Servlet 6.1
*/
void sendRedirect(String location, int sc, boolean clearBuffer) throws IOException;
/**
* Sends a 103 response to the client using the current response headers. This method does not commit the response
* and may be called multiple times before the response is committed. The current response headers may include some
* headers that have been added automatically by the container.
* <p>
* This method has no effect if called after the response has been committed.
*
* @since Servlet 6.2
*/
void sendEarlyHints();
/**
* Sets a response header with the given name and date-value. The date is specified in terms of milliseconds since
* the epoch. If the header had already been set, the new value overwrites the previous one. The
* <code>containsHeader</code> method can be used to test for the presence of a header before setting its value.
*
* @param name the name of the header to set
* @param date the assigned date value
*
* @see #containsHeader
* @see #addDateHeader
*/
void setDateHeader(String name, long date);
/**
* Adds a response header with the given name and date-value. The date is specified in terms of milliseconds since
* the epoch. This method allows response headers to have multiple values.
*
* @param name the name of the header to set
* @param date the additional date value
*
* @see #setDateHeader
*/
void addDateHeader(String name, long date);
/**
* Sets a response header with the given name and value. If the header had already been set, the new value
* overwrites the previous one. The <code>containsHeader</code> method can be used to test for the presence of a
* header before setting its value.
*
* @param name the name of the header
* @param value the header value If it contains octet string, it should be encoded according to RFC 2047
* (http://www.ietf.org/rfc/rfc2047.txt)
*
* @see #containsHeader
* @see #addHeader
*/
void setHeader(String name, String value);
/**
* Adds a response header with the given name and value. This method allows response headers to have multiple
* values.
*
* @param name the name of the header
* @param value the additional header value If it contains octet string, it should be encoded according to RFC 2047
* (http://www.ietf.org/rfc/rfc2047.txt)
*
* @see #setHeader
*/
void addHeader(String name, String value);
/**
* Sets a response header with the given name and integer value. If the header had already been set, the new value
* overwrites the previous one. The <code>containsHeader</code> method can be used to test for the presence of a
* header before setting its value.
*
* @param name the name of the header
* @param value the assigned integer value
*
* @see #containsHeader
* @see #addIntHeader
*/
void setIntHeader(String name, int value);
/**
* Adds a response header with the given name and integer value. This method allows response headers to have
* multiple values.
*
* @param name the name of the header
* @param value the assigned integer value
*
* @see #setIntHeader
*/
void addIntHeader(String name, int value);
/**
* Sets the status code for this response. This method is used to set the return status code when there is no error
* (for example, for the status codes SC_OK or SC_MOVED_TEMPORARILY). If there is an error, and the caller wishes to
* invoke an error-page defined in the web application, the <code>sendError</code> method should be used instead.
* <p>
* The container clears the buffer and sets the Location header, preserving cookies and other headers.
*
* @param sc the status code
*
* @see #sendError
*/
void setStatus(int sc);
/**
* Get the HTTP status code for this Response.
*
* @return The HTTP status code for this Response
*
* @since Servlet 3.0
*/
int getStatus();
/**
* Return the value for the specified header, or <code>null</code> if this header has not been set. If more than one
* value was added for this name, only the first is returned; use {@link #getHeaders(String)} to retrieve all of
* them.
*
* @param name Header name to look up
*
* @return The first value for the specified header. This is the raw value so if multiple values are specified in
* the first header then they will be returned as a single header value .
*
* @since Servlet 3.0
*/
String getHeader(String name);
/**
* Return a Collection of all the header values associated with the specified header name.
*
* @param name Header name to look up
*
* @return The values for the specified header. These are the raw values so if multiple values are specified in a
* single header that will be returned as a single header value.
*
* @since Servlet 3.0
*/
Collection<String> getHeaders(String name);
/**
* Get the header names set for this HTTP response.
*
* @return The header names set for this HTTP response.
*
* @since Servlet 3.0
*/
Collection<String> getHeaderNames();
/**
* Configure the supplier of the trailer headers. The supplier will be called in the scope of the thread that
* completes the response. <br>
* Trailers that don't meet the requirements of RFC 7230, section 4.1.2 will be ignored. <br>
* The default implementation is a NO-OP.
*
* @param supplier The supplier for the trailer headers
*
* @throws IllegalStateException if this method is called when the underlying protocol does not support trailer
* headers or if using HTTP/1.1 and the response has already been committed
*
* @since Servlet 4.0
*/
default void setTrailerFields(Supplier<Map<String,String>> supplier) {
// NO-OP
}
/**
* Obtain the supplier of the trailer headers. <br>
* The default implementation returns null.
*
* @return The supplier for the trailer headers
*
* @since Servlet 4.0
*/
default Supplier<Map<String,String>> getTrailerFields() {
return null;
}
/*
* Server status codes; see RFC 7231.
*/
/**
* Status code (100) indicating the client can continue.
*/
int SC_CONTINUE = 100;
/**
* Status code (101) indicating the server is switching protocols according to Upgrade header.
*/
int SC_SWITCHING_PROTOCOLS = 101;
/**
* Status code (103) indicating that the server is likely to send a final response containing the headers present in
* this informational response.
*
* @since Servlet 6.2
*/
int SC_EARLY_HINTS = 103;
/**
* Status code (200) indicating the request succeeded normally.
*/
int SC_OK = 200;
/**
* Status code (201) indicating the request succeeded and created a new resource on the server.
*/
int SC_CREATED = 201;
/**
* Status code (202) indicating that a request was accepted for processing, but was not completed.
*/
int SC_ACCEPTED = 202;
/**
* Status code (203) indicating that the meta information presented by the client did not originate from the server.
*/
int SC_NON_AUTHORITATIVE_INFORMATION = 203;
/**
* Status code (204) indicating that the request succeeded but that there was no new information to return.
*/
int SC_NO_CONTENT = 204;
/**
* Status code (205) indicating that the agent <em>SHOULD</em> reset the document view which caused the request to
* be sent.
*/
int SC_RESET_CONTENT = 205;
/**
* Status code (206) indicating that the server has fulfilled the partial GET request for the resource.
*/
int SC_PARTIAL_CONTENT = 206;
/**
* Status code (300) indicating that the requested resource corresponds to any one of a set of representations, each
* with its own specific location.
*/
int SC_MULTIPLE_CHOICES = 300;
/**
* Status code (301) indicating that the resource has permanently moved to a new location, and that future
* references should use a new URI with their requests.
*/
int SC_MOVED_PERMANENTLY = 301;
/**
* Status code (302) indicating that the resource has temporarily moved to another location, but that future
* references should still use the original URI to access the resource. This definition is being retained for
* backwards compatibility. SC_FOUND is now the preferred definition.
*/
int SC_MOVED_TEMPORARILY = 302;
/**
* Status code (302) indicating that the resource reside temporarily under a different URI. Since the redirection
* might be altered on occasion, the client should continue to use the Request-URI for future requests.(HTTP/1.1) To
* represent the status code (302), it is recommended to use this variable.
*/
int SC_FOUND = 302;
/**
* Status code (303) indicating that the response to the request can be found under a different URI.
*/
int SC_SEE_OTHER = 303;
/**
* Status code (304) indicating that a conditional GET operation found that the resource was available and not
* modified.
*/
int SC_NOT_MODIFIED = 304;
/**
* Status code (305) indicating that the requested resource <em>MUST</em> be accessed through the proxy given by the
* <code><em>Location</em></code> field.
*/
int SC_USE_PROXY = 305;
/**
* Status code (307) indicating that the requested resource resides temporarily under a different URI. The temporary
* URI <em>SHOULD</em> be given by the <code><em>Location</em></code> field in the response.
*/
int SC_TEMPORARY_REDIRECT = 307;
/**
* Status code (308) indicating that the requested resource resides permanently under a different URI. The new URI
* <em>SHOULD</em> be given by the <code><em>Location</em></code> field in the response.
*
* @since Servlet 6.1
*/
int SC_PERMANENT_REDIRECT = 308;
/**
* Status code (400) indicating the request sent by the client was syntactically incorrect.
*/
int SC_BAD_REQUEST = 400;
/**
* Status code (401) indicating that the request requires HTTP authentication.
*/
int SC_UNAUTHORIZED = 401;
/**
* Status code (402) reserved for future use.
*/
int SC_PAYMENT_REQUIRED = 402;
/**
* Status code (403) indicating the server understood the request but refused to fulfill it.
*/
int SC_FORBIDDEN = 403;
/**
* Status code (404) indicating that the requested resource is not available.
*/
int SC_NOT_FOUND = 404;
/**
* Status code (405) indicating that the method specified in the <code><em>Request-Line</em></code> is not allowed
* for the resource identified by the <code><em>Request-URI</em></code>.
*/
int SC_METHOD_NOT_ALLOWED = 405;
/**
* Status code (406) indicating that the resource identified by the request is only capable of generating response
* entities which have content characteristics not acceptable according to the accept headers sent in the request.
*/
int SC_NOT_ACCEPTABLE = 406;
/**
* Status code (407) indicating that the client <em>MUST</em> first authenticate itself with the proxy.
*/
int SC_PROXY_AUTHENTICATION_REQUIRED = 407;
/**
* Status code (408) indicating that the client did not produce a request within the time that the server was
* prepared to wait.
*/
int SC_REQUEST_TIMEOUT = 408;
/**
* Status code (409) indicating that the request could not be completed due to a conflict with the current state of
* the resource.
*/
int SC_CONFLICT = 409;
/**
* Status code (410) indicating that the resource is no longer available at the server and no forwarding address is
* known. This condition <em>SHOULD</em> be considered permanent.
*/
int SC_GONE = 410;
/**
* Status code (411) indicating that the request cannot be handled without a defined
* <code><em>Content-Length</em></code>.
*/
int SC_LENGTH_REQUIRED = 411;
/**
* Status code (412) indicating that the precondition given in one or more of the request-header fields evaluated to
* false when it was tested on the server.
*/
int SC_PRECONDITION_FAILED = 412;
/**
* Status code (413) indicating that the server is refusing to process the request because the request entity is
* larger than the server is willing or able to process.
*/
int SC_REQUEST_ENTITY_TOO_LARGE = 413;
/**
* Status code (414) indicating that the server is refusing to service the request because the
* <code><em>Request-URI</em></code> is longer than the server is willing to interpret.
*/
int SC_REQUEST_URI_TOO_LONG = 414;
/**
* Status code (415) indicating that the server is refusing to service the request because the entity of the request
* is in a format not supported by the requested resource for the requested method.
*/
int SC_UNSUPPORTED_MEDIA_TYPE = 415;
/**
* Status code (416) indicating that the server cannot serve the requested byte range.
*/
int SC_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
/**
* Status code (417) indicating that the server could not meet the expectation given in the Expect request header.
*/
int SC_EXPECTATION_FAILED = 417;
/**
* Status code (421) indicating that the server is unwilling or unable to produce an authoritative response for the
* target URI.
*
* @since Servlet 6.1
*/
int SC_MISDIRECTED_REQUEST = 421;
/**
* Status code (422) indicating that the server understands the content type of the request but is unable to process
* the contained instructions.
*
* @since Servlet 6.1
*/
int SC_UNPROCESSABLE_CONTENT = 422;
/**
* Status code (426) indicating that the server refuses to perform the request using the current protocol but may be
* willing to do so after the client upgrades to a different protocol. The server must include an appropriate
* {@code Upgrade} header in the response.
*
* @since Servlet 6.1
*/
int SC_UPGRADE_REQUIRED = 426;
/**
* Status code (500) indicating an error inside the HTTP server which prevented it from fulfilling the request.
*/
int SC_INTERNAL_SERVER_ERROR = 500;
/**
* Status code (501) indicating the HTTP server does not support the functionality needed to fulfill the request.
*/
int SC_NOT_IMPLEMENTED = 501;
/**
* Status code (502) indicating that the HTTP server received an invalid response from a server it consulted when
* acting as a proxy or gateway.
*/
int SC_BAD_GATEWAY = 502;
/**
* Status code (503) indicating that the HTTP server is temporarily overloaded, and unable to handle the request.
*/
int SC_SERVICE_UNAVAILABLE = 503;
/**
* Status code (504) indicating that the server did not receive a timely response from the upstream server while
* acting as a gateway or proxy.
*/
int SC_GATEWAY_TIMEOUT = 504;
/**
* Status code (505) indicating that the server does not support or refuses to support the HTTP protocol version
* that was used in the request message.
*/
int SC_HTTP_VERSION_NOT_SUPPORTED = 505;
}