Module jakarta.servlet

Package jakarta.servlet.http

Interface HttpServletResponse

All Superinterfaces:

ServletResponse

All Known Implementing Classes:

HttpServletResponseWrapper, ViewHandlerResponseWrapper

public interface HttpServletResponse
extends ServletResponse

Extends the ServletResponse interface to provide HTTP-specific functionality in sending a response. For example, it has methods to access HTTP headers and cookies.

The servlet container creates an HttpServletResponse object and passes it as an argument to the servlet's service methods (doGet, doPost, etc).

See Also:

• ServletResponse

Field Summary

Fields

Modifier and Type	Field	Description
static final int	SC_ACCEPTED	Status code (202) indicating that a request was accepted for processing, but was not completed.
static final int	SC_BAD_GATEWAY	Status code (502) indicating that the HTTP server received an invalid response from a server it consulted when acting as a proxy or gateway.
static final int	SC_BAD_REQUEST	Status code (400) indicating the request sent by the client was syntactically incorrect.
static final int	SC_CONFLICT	Status code (409) indicating that the request could not be completed due to a conflict with the current state of the resource.
static final int	SC_CONTINUE	Status code (100) indicating the client can continue.
static final int	SC_CREATED	Status code (201) indicating the request succeeded and created a new resource on the server.
static final int	SC_EXPECTATION_FAILED	Status code (417) indicating that the server could not meet the expectation given in the Expect request header.
static final int	SC_FORBIDDEN	Status code (403) indicating the server understood the request but refused to fulfill it.
static final int	SC_FOUND	Status code (302) indicating that the resource reside temporarily under a different URI.
static final int	SC_GATEWAY_TIMEOUT	Status code (504) indicating that the server did not receive a timely response from the upstream server while acting as a gateway or proxy.
static final int	SC_GONE	Status code (410) indicating that the resource is no longer available at the server and no forwarding address is known.
static final int	SC_HTTP_VERSION_NOT_SUPPORTED	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.
static final int	SC_INTERNAL_SERVER_ERROR	Status code (500) indicating an error inside the HTTP server which prevented it from fulfilling the request.
static final int	SC_LENGTH_REQUIRED	Status code (411) indicating that the request cannot be handled without a defined Content-Length.
static final int	SC_METHOD_NOT_ALLOWED	Status code (405) indicating that the method specified in the Request-Line is not allowed for the resource identified by the Request-URI.
static final int	SC_MISDIRECTED_REQUEST	Status code (421) indicating that the server is unwilling or unable to produce an authoritative response for the target URI.
static final int	SC_MOVED_PERMANENTLY	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.
static final int	SC_MOVED_TEMPORARILY	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.
static final int	SC_MULTIPLE_CHOICES	Status code (300) indicating that the requested resource corresponds to any one of a set of representations, each with its own specific location.
static final int	SC_NO_CONTENT	Status code (204) indicating that the request succeeded but that there was no new information to return.
static final int	SC_NON_AUTHORITATIVE_INFORMATION	Status code (203) indicating that the meta information presented by the client did not originate from the server.
static final int	SC_NOT_ACCEPTABLE	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.
static final int	SC_NOT_FOUND	Status code (404) indicating that the requested resource is not available.
static final int	SC_NOT_IMPLEMENTED	Status code (501) indicating the HTTP server does not support the functionality needed to fulfill the request.
static final int	SC_NOT_MODIFIED	Status code (304) indicating that a conditional GET operation found that the resource was available and not modified.
static final int	SC_OK	Status code (200) indicating the request succeeded normally.
static final int	SC_PARTIAL_CONTENT	Status code (206) indicating that the server has fulfilled the partial GET request for the resource.
static final int	SC_PAYMENT_REQUIRED	Status code (402) reserved for future use.
static final int	SC_PERMANENT_REDIRECT	Status code (308) indicating that the requested resource resides permanently under a different URI.
static final int	SC_PRECONDITION_FAILED	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.
static final int	SC_PROXY_AUTHENTICATION_REQUIRED	Status code (407) indicating that the client MUST first authenticate itself with the proxy.
static final int	SC_REQUEST_ENTITY_TOO_LARGE	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.
static final int	SC_REQUEST_TIMEOUT	Status code (408) indicating that the client did not produce a request within the time that the server was prepared to wait.
static final int	SC_REQUEST_URI_TOO_LONG	Status code (414) indicating that the server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.
static final int	SC_REQUESTED_RANGE_NOT_SATISFIABLE	Status code (416) indicating that the server cannot serve the requested byte range.
static final int	SC_RESET_CONTENT	Status code (205) indicating that the agent SHOULD reset the document view which caused the request to be sent.
static final int	SC_SEE_OTHER	Status code (303) indicating that the response to the request can be found under a different URI.
static final int	SC_SERVICE_UNAVAILABLE	Status code (503) indicating that the HTTP server is temporarily overloaded, and unable to handle the request.
static final int	SC_SWITCHING_PROTOCOLS	Status code (101) indicating the server is switching protocols according to Upgrade header.
static final int	SC_TEMPORARY_REDIRECT	Status code (307) indicating that the requested resource resides temporarily under a different URI.
static final int	SC_UNAUTHORIZED	Status code (401) indicating that the request requires HTTP authentication.
static final int	SC_UNPROCESSABLE_CONTENT	Status code (422) indicating that the server understands the content type of the request but is unable to process the contained instructions.
static final int	SC_UNSUPPORTED_MEDIA_TYPE	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.
static final int	SC_UPGRADE_REQUIRED	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.
static final int	SC_USE_PROXY	Status code (305) indicating that the requested resource MUST be accessed through the proxy given by the Location field.

Method Summary

Modifier and Type	Method	Description
void	addCookie(Cookie cookie)	Adds the specified cookie to the response.
void	addDateHeader(String name, long date)	Adds a response header with the given name and date-value.
void	addHeader(String name, String value)	Adds a response header with the given name and value.
void	addIntHeader(String name, int value)	Adds a response header with the given name and integer value.
boolean	containsHeader(String name)	Returns a boolean indicating whether the named response header has already been set.
String	encodeRedirectURL(String url)	Encodes the specified URL for use in the sendRedirect method or, if encoding is not needed, returns the URL unchanged.
String	encodeURL(String url)	Encodes the specified URL by including the session ID, or, if encoding is not needed, returns the URL unchanged.
String	getHeader(String name)	Gets the value of the response header with the given name.
Collection<String>	getHeaderNames()	Gets the names of the headers of this response.
Collection<String>	getHeaders(String name)	Gets the values of the response header with the given name.
int	getStatus()	Gets the current status code of this response.
default Supplier<Map<String,String>>	getTrailerFields()	Gets the supplier of trailer headers.
void	sendError(int sc)	Sends an error response to the client using the specified status code and clears the buffer.
void	sendError(int sc, String msg)	Sends an error response to the client using the specified status and clears the buffer.
default void	sendRedirect(String location)	Sends a redirect response to the client using the specified redirect location URL with the status code SC_FOUND 302 (Found), clears the response buffer and commits the response.
default void	sendRedirect(String location, boolean clearBuffer)	Sends a redirect response to the client using the specified redirect location URL with the status code SC_FOUND 302 (Found), optionally clears the response buffer and commits the response.
default void	sendRedirect(String location, int sc)	Sends a redirect response to the client using the specified redirect location URL and status code, clears the response buffer and commits the response.
void	sendRedirect(String location, int sc, boolean clearBuffer)	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.
void	setDateHeader(String name, long date)	Sets a response header with the given name and date-value.
void	setHeader(String name, String value)	Sets a response header with the given name and value.
void	setIntHeader(String name, int value)	Sets a response header with the given name and integer value.
void	setStatus(int sc)	Sets the status code for this response.
default void	setTrailerFields(Supplier<Map<String,String>> supplier)	Sets the supplier of trailer headers.

Methods inherited from interface jakarta.servlet.ServletResponse

flushBuffer, getBufferSize, getCharacterEncoding, getContentType, getLocale, getOutputStream, getWriter, isCommitted, reset, resetBuffer, setBufferSize, setCharacterEncoding, setCharacterEncoding, setContentLength, setContentLengthLong, setContentType, setLocale

Field Details

SC_CONTINUE

static final int SC_CONTINUE

Status code (100) indicating the client can continue.

See Also:

• Constant Field Values

SC_SWITCHING_PROTOCOLS

static final int SC_SWITCHING_PROTOCOLS

Status code (101) indicating the server is switching protocols according to Upgrade header.

See Also:

• Constant Field Values

SC_OK

static final int SC_OK

Status code (200) indicating the request succeeded normally.

See Also:

• Constant Field Values

SC_CREATED

static final int SC_CREATED

Status code (201) indicating the request succeeded and created a new resource on the server.

See Also:

• Constant Field Values

SC_ACCEPTED

static final int SC_ACCEPTED

Status code (202) indicating that a request was accepted for processing, but was not completed.

See Also:

• Constant Field Values

SC_NON_AUTHORITATIVE_INFORMATION

static final int SC_NON_AUTHORITATIVE_INFORMATION

Status code (203) indicating that the meta information presented by the client did not originate from the server.

See Also:

• Constant Field Values

SC_NO_CONTENT

static final int SC_NO_CONTENT

Status code (204) indicating that the request succeeded but that there was no new information to return.

See Also:

• Constant Field Values

SC_RESET_CONTENT

static final int SC_RESET_CONTENT

Status code (205) indicating that the agent SHOULD reset the document view which caused the request to be sent.

See Also:

• Constant Field Values

SC_PARTIAL_CONTENT

static final int SC_PARTIAL_CONTENT

Status code (206) indicating that the server has fulfilled the partial GET request for the resource.

See Also:

• Constant Field Values

SC_MULTIPLE_CHOICES

static final int SC_MULTIPLE_CHOICES

Status code (300) indicating that the requested resource corresponds to any one of a set of representations, each with its own specific location.

See Also:

• Constant Field Values

SC_MOVED_PERMANENTLY

static final int SC_MOVED_PERMANENTLY

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.

See Also:

• Constant Field Values

SC_MOVED_TEMPORARILY

static final int SC_MOVED_TEMPORARILY

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.

See Also:

• Constant Field Values

SC_FOUND

static final int SC_FOUND

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.

See Also:

• Constant Field Values

SC_SEE_OTHER

static final int SC_SEE_OTHER

Status code (303) indicating that the response to the request can be found under a different URI.

See Also:

• Constant Field Values

SC_NOT_MODIFIED

static final int SC_NOT_MODIFIED

Status code (304) indicating that a conditional GET operation found that the resource was available and not modified.

See Also:

• Constant Field Values

SC_USE_PROXY

static final int SC_USE_PROXY

Status code (305) indicating that the requested resource MUST be accessed through the proxy given by the Location field.

See Also:

• Constant Field Values

SC_TEMPORARY_REDIRECT

static final int SC_TEMPORARY_REDIRECT

Status code (307) indicating that the requested resource resides temporarily under a different URI. The temporary URI SHOULD be given by the Location field in the response.

See Also:

• Constant Field Values

SC_PERMANENT_REDIRECT

static final int SC_PERMANENT_REDIRECT

Status code (308) indicating that the requested resource resides permanently under a different URI. The new URI SHOULD be given by the Location field in the response.

Since:

Servlet 6.1

See Also:

• Constant Field Values

SC_BAD_REQUEST

static final int SC_BAD_REQUEST

Status code (400) indicating the request sent by the client was syntactically incorrect.

See Also:

• Constant Field Values

SC_UNAUTHORIZED

static final int SC_UNAUTHORIZED

Status code (401) indicating that the request requires HTTP authentication.

See Also:

• Constant Field Values

SC_PAYMENT_REQUIRED

static final int SC_PAYMENT_REQUIRED

Status code (402) reserved for future use.

See Also:

• Constant Field Values

SC_FORBIDDEN

static final int SC_FORBIDDEN

Status code (403) indicating the server understood the request but refused to fulfill it.

See Also:

• Constant Field Values

SC_NOT_FOUND

static final int SC_NOT_FOUND

Status code (404) indicating that the requested resource is not available.

See Also:

• Constant Field Values

SC_METHOD_NOT_ALLOWED

static final int SC_METHOD_NOT_ALLOWED

Status code (405) indicating that the method specified in the Request-Line is not allowed for the resource identified by the Request-URI.

See Also:

• Constant Field Values

SC_NOT_ACCEPTABLE

static final int SC_NOT_ACCEPTABLE

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.

See Also:

• Constant Field Values

SC_PROXY_AUTHENTICATION_REQUIRED

static final int SC_PROXY_AUTHENTICATION_REQUIRED

Status code (407) indicating that the client MUST first authenticate itself with the proxy.

See Also:

• Constant Field Values

SC_REQUEST_TIMEOUT

static final int SC_REQUEST_TIMEOUT

Status code (408) indicating that the client did not produce a request within the time that the server was prepared to wait.

See Also:

• Constant Field Values

SC_CONFLICT

static final int SC_CONFLICT

Status code (409) indicating that the request could not be completed due to a conflict with the current state of the resource.

See Also:

• Constant Field Values

SC_GONE

static final int SC_GONE

Status code (410) indicating that the resource is no longer available at the server and no forwarding address is known. This condition SHOULD be considered permanent.

See Also:

• Constant Field Values

SC_LENGTH_REQUIRED

static final int SC_LENGTH_REQUIRED

Status code (411) indicating that the request cannot be handled without a defined Content-Length.

See Also:

• Constant Field Values

SC_PRECONDITION_FAILED

static final int SC_PRECONDITION_FAILED

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.

See Also:

• Constant Field Values

SC_REQUEST_ENTITY_TOO_LARGE

static final int SC_REQUEST_ENTITY_TOO_LARGE

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.

See Also:

• Constant Field Values

SC_REQUEST_URI_TOO_LONG

static final int SC_REQUEST_URI_TOO_LONG

Status code (414) indicating that the server is refusing to service the request because the Request-URI is longer than the server is willing to interpret.

See Also:

• Constant Field Values

SC_UNSUPPORTED_MEDIA_TYPE

static final int SC_UNSUPPORTED_MEDIA_TYPE

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.

See Also:

• Constant Field Values

SC_REQUESTED_RANGE_NOT_SATISFIABLE

static final int SC_REQUESTED_RANGE_NOT_SATISFIABLE

Status code (416) indicating that the server cannot serve the requested byte range.

See Also:

• Constant Field Values

SC_EXPECTATION_FAILED

static final int SC_EXPECTATION_FAILED

Status code (417) indicating that the server could not meet the expectation given in the Expect request header.

See Also:

• Constant Field Values

SC_MISDIRECTED_REQUEST

static final int SC_MISDIRECTED_REQUEST

Status code (421) indicating that the server is unwilling or unable to produce an authoritative response for the target URI.

Since:

Servlet 6.1

See Also:

• Constant Field Values

SC_UNPROCESSABLE_CONTENT

static final int SC_UNPROCESSABLE_CONTENT

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

See Also:

• Constant Field Values

SC_UPGRADE_REQUIRED

static final int SC_UPGRADE_REQUIRED

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 Upgrade header in the response.

Since:

Servlet 6.1

See Also:

• Constant Field Values

SC_INTERNAL_SERVER_ERROR

static final int SC_INTERNAL_SERVER_ERROR

Status code (500) indicating an error inside the HTTP server which prevented it from fulfilling the request.

See Also:

• Constant Field Values

SC_NOT_IMPLEMENTED

static final int SC_NOT_IMPLEMENTED

Status code (501) indicating the HTTP server does not support the functionality needed to fulfill the request.

See Also:

• Constant Field Values

SC_BAD_GATEWAY

static final int SC_BAD_GATEWAY

Status code (502) indicating that the HTTP server received an invalid response from a server it consulted when acting as a proxy or gateway.

See Also:

• Constant Field Values

SC_SERVICE_UNAVAILABLE

static final int SC_SERVICE_UNAVAILABLE

Status code (503) indicating that the HTTP server is temporarily overloaded, and unable to handle the request.

See Also:

• Constant Field Values

SC_GATEWAY_TIMEOUT

static final int SC_GATEWAY_TIMEOUT

Status code (504) indicating that the server did not receive a timely response from the upstream server while acting as a gateway or proxy.

See Also:

• Constant Field Values

SC_HTTP_VERSION_NOT_SUPPORTED

static final int SC_HTTP_VERSION_NOT_SUPPORTED

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.

See Also:

• Constant Field Values

Method Details

addCookie

void addCookie(Cookie cookie)

Adds the specified cookie to the response. This method can be called multiple times to set more than one cookie.

This method has no effect if called after the response has been committed.

Parameters:

cookie - the Cookie to return to the client

containsHeader

boolean containsHeader(String name)

Returns a boolean indicating whether the named response header has already been set.

Parameters:

name - the header name

Returns:

true if the named response header has already been set; false otherwise

encodeURL

String encodeURL(String url)

Encodes the specified URL by including the session ID, 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.

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.

If the URL is relative, it is always relative to the current HttpServletRequest.

Parameters:

url - the url to be encoded.

Returns:

the encoded URL if encoding is needed; the unchanged URL otherwise.

Throws:

IllegalArgumentException - if the url is not valid

encodeRedirectURL

String encodeRedirectURL(String url)

Encodes the specified URL for use in the sendRedirect 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. For example, if the browser supports cookies, or session tracking is turned off, URL encoding is unnecessary. 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 encodeURL method.

All URLs sent to the HttpServletResponse.sendRedirect method should be run through this method. Otherwise, URL rewriting cannot be used with browsers which do not support cookies.

If the URL is relative, it is always relative to the current HttpServletRequest.

Parameters:

url - the url to be encoded.

Returns:

the encoded URL if encoding is needed; the unchanged URL otherwise.

Throws:

IllegalArgumentException - if the url is not valid

See Also:

• sendRedirect(java.lang.String)

sendError

void sendError(int sc,
 String msg)
        throws IOException

Sends an error response to the client using the specified status and clears the 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". The caller is not responsible for escaping or re-encoding the message to ensure it is safe with respect to the current response encoding and content type. This aspect of safety is the responsibility of the container, as it is generating the error page containing the message. The server will preserve cookies and may clear or update any headers needed to serve the error page as a valid response.

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 and the msg parameter will be ignored.

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.

Parameters:

sc - the error status code

msg - the descriptive message

Throws:

IOException - If an input or output exception occurs

IllegalStateException - If the response was committed

sendError

void sendError(int sc)
        throws IOException

Sends an error response to the client using the specified status code and clears the buffer. The server will preserve cookies and may clear or update any headers needed to serve the error page as a valid response. If an error-page declaration has been made for the web application corresponding to the status code passed in, it will be served back the error page

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.

Parameters:

sc - the error status code

Throws:

IOException - If an input or output exception occurs

IllegalStateException - If the response was committed before this method call

sendRedirect

default void sendRedirect(String location)
                   throws IOException

Sends a redirect response to the client using the specified redirect location URL with the status code 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.

This method has no effect if called from an include.

Parameters:

location - the redirect location URL (may be absolute or relative)

Throws:

IOException - If an input or output exception occurs

IllegalArgumentException - If a relative URL is given and cannot be converted into an absolute URL

IllegalStateException - If the response was already committed when this method was called

See Also:

• sendRedirect(String, int, boolean)

sendRedirect

default void sendRedirect(String location,
 boolean clearBuffer)
                   throws IOException

Sends a redirect response to the client using the specified redirect location URL with the status code 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.

This method has no effect if called from an include.

Parameters:

location - the redirect location URL (may be absolute or relative)

clearBuffer - if true, clear the buffer and replace it with the data set by this method otherwise retain the existing buffer

Throws:

IOException - If an input or output exception occurs

IllegalArgumentException - If a relative URL is given and cannot be converted into an absolute URL

IllegalStateException - If the response was already committed when this method was called

Since:

Servlet 6.1

See Also:

• sendRedirect(String, int, boolean)

sendRedirect

default void sendRedirect(String location,
 int sc)
                   throws IOException

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.

This method has no effect if called from an include.

Parameters:

location - the redirect location URL (may be absolute or relative)

sc - the status code to use for the redirect

Throws:

IOException - If an input or output exception occurs

IllegalArgumentException - If a relative URL is given and cannot be converted into an absolute URL

IllegalStateException - If the response was already committed when this method was called

Since:

Servlet 6.1

See Also:

• sendRedirect(String, int, boolean)

sendRedirect

void sendRedirect(String location,
 int sc,
 boolean clearBuffer)
           throws IOException

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.

This method has no effect if called from an include.

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:

• If the location is relative without a leading '/' the container interprets it as relative to the current request URI.
• If the location is relative with a leading '/' the container interprets it as relative to the servlet container root.
• If the location is relative with two leading '/' the container interprets it as a network-path reference (see RFC 3986: Uniform Resource Identifier (URI): Generic Syntax, section 4.2 "Relative Reference").

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.

Parameters:

location - the redirect location URL (may be absolute or relative)

sc - the status code to use for the redirect

clearBuffer - if true, clear the buffer and replace it with the data set by this method otherwise retain the existing buffer

Throws:

IOException - If an input or output exception occurs

IllegalArgumentException - If a relative URL is given and cannot be converted into an absolute URL

IllegalStateException - If the response was already committed when this method was called

Since:

Servlet 6.1

setDateHeader

void setDateHeader(String name,
 long date)

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 all previous values. The containsHeader method can be used to test for the presence of a header before setting its value.

This method has no effect if called after the response has been committed.

This method has no effect if null is passed for the name parameter.

Parameters:

name - the name of the header to set

date - the assigned date value

See Also:

• containsHeader(java.lang.String)
• addDateHeader(java.lang.String, long)

addDateHeader

void addDateHeader(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.

This method has no effect if called after the response has been committed.

This method has no effect if null is passed for the name parameter.

Parameters:

name - the name of the header to set

date - the additional date value

See Also:

• setDateHeader(java.lang.String, long)

setHeader

void setHeader(String name,
 String value)

Sets a response header with the given name and value. If the header had already been set, the new value overwrites all previous values. The containsHeader method can be used to test for the presence of a header before setting its value.

This method has no effect if called after the response has been committed.

This method has no effect if null is passed for the name parameter.

Passing null as the value removes all headers with the given name.

Note that the empty string is a valid header value.

Parameters:

name - the name of the header

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 Also:

• containsHeader(java.lang.String)
• addHeader(java.lang.String, java.lang.String)

addHeader

void addHeader(String name,
 String value)

Adds a response header with the given name and value. This method allows response headers to have multiple values.

This method has no effect if called after the response has been committed.

This method has no effect if null is passed for either the name or value parameters.

Note that the empty string is a valid header value.

Parameters:

name - the name of the header

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 Also:

• setHeader(java.lang.String, java.lang.String)

setIntHeader

void setIntHeader(String name,
 int value)

Sets a response header with the given name and integer value. If the header had already been set, the new value overwrites all previous values. The containsHeader method can be used to test for the presence of a header before setting its value.

This method has no effect if called after the response has been committed.

This method has no effect if null is passed for the name parameter.

Parameters:

name - the name of the header

value - the assigned integer value

See Also:

• containsHeader(java.lang.String)
• addIntHeader(java.lang.String, int)

addIntHeader

void addIntHeader(String name,
 int value)

Adds a response header with the given name and integer value. This method allows response headers to have multiple values.

This method has no effect if called after the response has been committed.

This method has no effect if null is passed for the name parameter.

Parameters:

name - the name of the header

value - the assigned integer value

See Also:

• setIntHeader(java.lang.String, int)

setStatus

void setStatus(int sc)

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 SC_OK or SC_MOVED_TEMPORARILY status codes).

If this method is used to set an error code, then the container's error page mechanism will not be triggered. If there is an error and the caller wishes to invoke an error page defined in the web application, then sendError(int, java.lang.String) must be used instead.

This method preserves any cookies and other response headers.

Valid status codes are those in the 2XX, 3XX, 4XX, and 5XX ranges. Other status codes are treated as container specific.

This method has no effect if called after the response has been committed.

Parameters:

sc - the status code

See Also:

• sendError(int, java.lang.String)

getStatus

int getStatus()

Gets the current status code of this response.

Returns:

the current status code of this response

Since:

Servlet 3.0

getHeader

String getHeader(String name)

Gets the value of the response header with the given name.

If a response header with the given name exists and contains multiple values, the value that was added first will be returned.

This method considers only response headers set or added via setHeader(java.lang.String, java.lang.String), addHeader(java.lang.String, java.lang.String), setDateHeader(java.lang.String, long), addDateHeader(java.lang.String, long), setIntHeader(java.lang.String, int), or addIntHeader(java.lang.String, int), respectively.

Parameters:

name - the name of the response header whose value to return

Returns:

the value of the response header with the given name, or null if no header with the given name has been set on this response

Since:

Servlet 3.0

getHeaders

Collection<String> getHeaders(String name)

Gets the values of the response header with the given name.

This method considers only response headers set or added via setHeader(java.lang.String, java.lang.String), addHeader(java.lang.String, java.lang.String), setDateHeader(java.lang.String, long), addDateHeader(java.lang.String, long), setIntHeader(java.lang.String, int), or addIntHeader(java.lang.String, int), respectively.

Any changes to the returned Collection must not affect this HttpServletResponse.

Parameters:

name - the name of the response header whose values to return

Returns:

a (possibly empty) Collection of the values of the response header with the given name

Since:

Servlet 3.0

getHeaderNames

Collection<String> getHeaderNames()

Gets the names of the headers of this response.

This method considers only response headers set or added via setHeader(java.lang.String, java.lang.String), addHeader(java.lang.String, java.lang.String), setDateHeader(java.lang.String, long), addDateHeader(java.lang.String, long), setIntHeader(java.lang.String, int), or addIntHeader(java.lang.String, int), respectively.

Any changes to the returned Collection must not affect this HttpServletResponse.

Returns:

a (possibly empty) Collection of the names of the headers of this response

Since:

Servlet 3.0

setTrailerFields

default void setTrailerFields(Supplier<Map<String,String>> supplier)

Sets the supplier of trailer headers.

The trailer header field value is defined as a comma-separated list (see Section 3.2.2 and Section 4.1.2 of RFC 7230).

The supplier will be called within the scope of whatever thread/call causes the response content to be completed. Typically this will be any thread calling close() on the output stream or writer.

The trailers that run afoul of the provisions of section 4.1.2 of RFC 7230 are ignored.

The RFC requires the name of every key that is to be in the supplied Map is included in the comma separated list that is the value of the "Trailer" response header. The application is responsible for ensuring this requirement is met. Failure to do so may lead to interoperability failures.

Parameters:

supplier - the supplier of trailer headers

Throws:

IllegalStateException - if it is invoked after the response has has been committed, or the trailer is not supported in the request, for instance, the underlying protocol is HTTP 1.0, or the response is not in chunked encoding in HTTP 1.1.

Since:

Servlet 4.0

getTrailerFields

default Supplier<Map<String,String>> getTrailerFields()

Gets the supplier of trailer headers.

Returns:

Supplier of trailer headers

Since:

Servlet 4.0