javax.servlet.http
Interface HttpServletResponse

All Superinterfaces:

ServletResponse

All Known Implementing Classes:

HttpServletResponseWrapper

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).

Author:

Various

See Also:

ServletResponse

Field Summary

static int	SC_ACCEPTED Status code (202) indicating that a request was accepted for processing, but was not completed.
static 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 int	SC_BAD_REQUEST Status code (400) indicating the request sent by the client was syntactically incorrect.
static 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 int	SC_CONTINUE Status code (100) indicating the client can continue.
static int	SC_CREATED Status code (201) indicating the request succeeded and created a new resource on the server.
static int	SC_EXPECTATION_FAILED Status code (417) indicating that the server could not meet the expectation given in the Expect request header.
static int	SC_FORBIDDEN Status code (403) indicating the server understood the request but refused to fulfill it.
static int	SC_FOUND Status code (302) indicating that the resource reside temporarily under a different URI.
static 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 int	SC_GONE Status code (410) indicating that the resource is no longer available at the server and no forwarding address is known.
static 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 int	SC_INTERNAL_SERVER_ERROR Status code (500) indicating an error inside the HTTP server which prevented it from fulfilling the request.
static int	SC_LENGTH_REQUIRED Status code (411) indicating that the request cannot be handled without a defined Content-Length.
static 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 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 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 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 int	SC_NO_CONTENT Status code (204) indicating that the request succeeded but that there was no new information to return.
static int	SC_NON_AUTHORITATIVE_INFORMATION Status code (203) indicating that the meta information presented by the client did not originate from the server.
static 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 int	SC_NOT_FOUND Status code (404) indicating that the requested resource is not available.
static int	SC_NOT_IMPLEMENTED Status code (501) indicating the HTTP server does not support the functionality needed to fulfill the request.
static int	SC_NOT_MODIFIED Status code (304) indicating that a conditional GET operation found that the resource was available and not modified.
static int	SC_OK Status code (200) indicating the request succeeded normally.
static int	SC_PARTIAL_CONTENT Status code (206) indicating that the server has fulfilled the partial GET request for the resource.
static int	SC_PAYMENT_REQUIRED Status code (402) reserved for future use.
static 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 int	SC_PROXY_AUTHENTICATION_REQUIRED Status code (407) indicating that the client MUST first authenticate itself with the proxy.
static 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 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 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 int	SC_REQUESTED_RANGE_NOT_SATISFIABLE Status code (416) indicating that the server cannot serve the requested byte range.
static int	SC_RESET_CONTENT Status code (205) indicating that the agent SHOULD reset the document view which caused the request to be sent.
static int	SC_SEE_OTHER Status code (303) indicating that the response to the request can be found under a different URI.
static int	SC_SERVICE_UNAVAILABLE Status code (503) indicating that the HTTP server is temporarily overloaded, and unable to handle the request.
static int	SC_SWITCHING_PROTOCOLS Status code (101) indicating the server is switching protocols according to Upgrade header.
static int	SC_TEMPORARY_REDIRECT Status code (307) indicating that the requested resource resides temporarily under a different URI.
static int	SC_UNAUTHORIZED Status code (401) indicating that the request requires HTTP authentication.
static 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 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

void	addCookie(Cookie cookie) Adds the specified cookie to the response.
void	addDateHeader(java.lang.String name, long date) Adds a response header with the given name and date-value.
void	addHeader(java.lang.String name, java.lang.String value) Adds a response header with the given name and value.
void	addIntHeader(java.lang.String name, int value) Adds a response header with the given name and integer value.
boolean	containsHeader(java.lang.String name) Returns a boolean indicating whether the named response header has already been set.
java.lang.String	encodeRedirectUrl(java.lang.String url) Deprecated. As of version 2.1, use encodeRedirectURL(String url) instead
java.lang.String	encodeRedirectURL(java.lang.String url) Encodes the specified URL for use in the sendRedirect method or, if encoding is not needed, returns the URL unchanged.
java.lang.String	encodeUrl(java.lang.String url) Deprecated. As of version 2.1, use encodeURL(String url) instead
java.lang.String	encodeURL(java.lang.String url) Encodes the specified URL by including the session ID in it, or, if encoding is not needed, returns the URL unchanged.
java.lang.String	getHeader(java.lang.String name) Gets the value of the response header with the given name.
java.util.Collection<java.lang.String>	getHeaderNames() Gets the names of the headers of this response.
java.util.Collection<java.lang.String>	getHeaders(java.lang.String name) Gets the values of the response header with the given name.
int	getStatus() Gets the current status code of this response.
void	sendError(int sc) Sends an error response to the client using the specified status code and clears the buffer.
void	sendError(int sc, java.lang.String msg) Sends an error response to the client using the specified status and clears the buffer.
void	sendRedirect(java.lang.String location) Sends a temporary redirect response to the client using the specified redirect location URL and clears the buffer.
void	setDateHeader(java.lang.String name, long date) Sets a response header with the given name and date-value.
void	setHeader(java.lang.String name, java.lang.String value) Sets a response header with the given name and value.
void	setIntHeader(java.lang.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.
void	setStatus(int sc, java.lang.String sm) Deprecated. As of version 2.1, due to ambiguous meaning of the message parameter. To set a status code use setStatus(int), to send an error with a description use sendError(int, String). Sets the status code and message for this response.

Methods inherited from interface javax.servlet.ServletResponse

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

Field Detail

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.

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SC_CREATED

static final int SC_CREATED

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

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SC_ACCEPTED

static final int SC_ACCEPTED

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

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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:

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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.

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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:

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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.

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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.

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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.

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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:

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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:

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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:

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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.

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SC_BAD_REQUEST

static final int SC_BAD_REQUEST

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

See Also:

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SC_UNAUTHORIZED

static final int SC_UNAUTHORIZED

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

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SC_PAYMENT_REQUIRED

static final int SC_PAYMENT_REQUIRED

Status code (402) reserved for future use.

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SC_FORBIDDEN

static final int SC_FORBIDDEN

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

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SC_NOT_FOUND

static final int SC_NOT_FOUND

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

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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.

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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.

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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.

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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.

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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.

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SC_LENGTH_REQUIRED

static final int SC_LENGTH_REQUIRED

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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Constant Field Values

Method Detail

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.

Parameters:

cookie - the Cookie to return to the client

containsHeader

boolean containsHeader(java.lang.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

java.lang.String encodeURL(java.lang.String url)

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.

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.

Parameters:

url - the url to be encoded.

Returns:

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

encodeRedirectURL

java.lang.String encodeRedirectURL(java.lang.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. 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.

Parameters:

url - the url to be encoded.

Returns:

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

See Also:

sendRedirect(java.lang.String), encodeUrl(java.lang.String)

encodeUrl

java.lang.String encodeUrl(java.lang.String url)

Deprecated. As of version 2.1, use encodeURL(String url) instead

Parameters:

url - the url to be encoded.

Returns:

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

encodeRedirectUrl

java.lang.String encodeRedirectUrl(java.lang.String url)

Deprecated. As of version 2.1, use encodeRedirectURL(String url) instead

Parameters:

url - the url to be encoded.

Returns:

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

sendError

void sendError(int sc,
               java.lang.String msg)
               throws java.io.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 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:

java.io.IOException - If an input or output exception occurs

IllegalStateException - If the response was committed

sendError

void sendError(int sc)
               throws java.io.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:

java.io.IOException - If an input or output exception occurs

IllegalStateException - If the response was committed before this method call

sendRedirect

void sendRedirect(java.lang.String location)
                  throws java.io.IOException

Sends a temporary redirect response to the client using the specified redirect location URL and clears the buffer. The buffer will be replaced with the data set by this method. Calling this method sets the status code to SC_FOUND 302 (Found). This method can accept relative URLs;the servlet container must convert the relative URL to an absolute URL before sending the response to the client. 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 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

Throws:

java.io.IOException - If an input or output exception occurs

IllegalStateException - If the response was committed or if a partial URL is given and cannot be converted into a valid URL

setDateHeader

void setDateHeader(java.lang.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 the previous one. The containsHeader method can be used to test for the presence of a header before setting its value.

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(java.lang.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.

Parameters:

name - the name of the header to set

date - the additional date value

See Also:

setDateHeader(java.lang.String, long)

setHeader

void setHeader(java.lang.String name,
               java.lang.String value)

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 containsHeader method can be used to test for the presence of a header before setting its 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(java.lang.String name,
               java.lang.String value)

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

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(java.lang.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 the previous one. The containsHeader method can be used to test for the presence of a header before setting its value.

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(java.lang.String name,
                  int value)

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

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.

Parameters:

sc - the status code

See Also:

sendError(int, java.lang.String)

setStatus

void setStatus(int sc,
               java.lang.String sm)

Deprecated. As of version 2.1, due to ambiguous meaning of the message parameter. To set a status code use setStatus(int), to send an error with a description use sendError(int, String). Sets the status code and message for this response.

Parameters:

sc - the status code

sm - the status message

getStatus

int getStatus()

Gets the current status code of this response.

Returns:

the current status code of this response

Since:

Servlet 3.0

getHeader

java.lang.String getHeader(java.lang.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

java.util.Collection<java.lang.String> getHeaders(java.lang.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

java.util.Collection<java.lang.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