Java-API：javax.servlet.http.HttpServletResponse

javax.servlet.http
Interface HttpServletResponse

All Superinterfaces:

ServletResponse

All Known Implementing Classes:

HttpServletResponseWrapper

public interfaceHttpServletResponse

extendsServletResponse

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

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

Version:

$Version$

Author:

Various

See Also:

ServletResponse

SC_CONTINUE

public static final int SC_CONTINUE

Status code (100) indicating the client can continue.

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Constant Field Values

SC_SWITCHING_PROTOCOLS

public static final int SC_SWITCHING_PROTOCOLS

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

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SC_OK

public static final int SC_OK

Status code (200) indicating the request succeeded normally.

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SC_CREATED

public 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

public 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

public 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.

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SC_NO_CONTENT

public 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

public static final int SC_RESET_CONTENT

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

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SC_PARTIAL_CONTENT

public 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

public 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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SC_MOVED_PERMANENTLY

public 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.

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SC_MOVED_TEMPORARILY

public 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.

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Constant Field Values

SC_FOUND

public 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

public static final int SC_SEE_OTHER

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

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SC_NOT_MODIFIED

public static final int SC_NOT_MODIFIED

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

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SC_USE_PROXY

public static final int SC_USE_PROXY

Status code (305) indicating that the requested resourceMUSTbe accessed through the proxy given by theLocationfield.

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SC_TEMPORARY_REDIRECT

public static final int SC_TEMPORARY_REDIRECT

Status code (307) indicating that the requested resource resides temporarily under a different URI. The temporary URISHOULDbe given by theLocationfield in the response.

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Constant Field Values

SC_BAD_REQUEST

public static final int SC_BAD_REQUEST

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

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SC_UNAUTHORIZED

public static final int SC_UNAUTHORIZED

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

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SC_PAYMENT_REQUIRED

public static final int SC_PAYMENT_REQUIRED

Status code (402) reserved for future use.

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SC_FORBIDDEN

public 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

public 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

public static final int SC_METHOD_NOT_ALLOWED

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

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SC_NOT_ACCEPTABLE

public 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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Constant Field Values

SC_PROXY_AUTHENTICATION_REQUIRED

public static final int SC_PROXY_AUTHENTICATION_REQUIRED

Status code (407) indicating that the clientMUSTfirst authenticate itself with the proxy.

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SC_REQUEST_TIMEOUT

public 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

public 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

public 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 conditionSHOULDbe considered permanent.

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SC_LENGTH_REQUIRED

public static final int SC_LENGTH_REQUIRED

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

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SC_PRECONDITION_FAILED

public 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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Constant Field Values

SC_REQUEST_ENTITY_TOO_LARGE

public 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.

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Constant Field Values

SC_REQUEST_URI_TOO_LONG

public static final int SC_REQUEST_URI_TOO_LONG

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

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Constant Field Values

SC_UNSUPPORTED_MEDIA_TYPE

public 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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Constant Field Values

SC_REQUESTED_RANGE_NOT_SATISFIABLE

public 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

public 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

public 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

public 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

public 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

public 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

public 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

public 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

addCookie

public void addCookie(Cookiecookie)

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

public boolean containsHeader(java.lang.Stringname)

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

Parameters:

name- the header name

Returns:

trueif the named response header has already been set;falseotherwise

encodeURL

public java.lang.String encodeURL(java.lang.Stringurl)

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

public java.lang.String encodeRedirectURL(java.lang.Stringurl)

Encodes the specified URL for use in thesendRedirectmethod 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 theencodeURLmethod.

All URLs sent to theHttpServletResponse.sendRedirectmethod 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

public java.lang.String encodeUrl(java.lang.Stringurl)

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

public java.lang.String encodeRedirectUrl(java.lang.Stringurl)

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

public void sendError(intsc,
                      java.lang.Stringmsg)
               throws java.io.IOException

Sends an error response to the client using the specified status. 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.

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

java.lang.IllegalStateException- If the response was committed

sendError

public void sendError(intsc)
               throws java.io.IOException

Sends an error response to the client using the specified status code and clearing the buffer.

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

java.lang.IllegalStateException- If the response was committed before this method call

sendRedirect

public void sendRedirect(java.lang.Stringlocation)
                  throws java.io.IOException

Sends a temporary redirect response to the client using the specified redirect location URL. 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

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

setDateHeader

public void setDateHeader(java.lang.Stringname,
                          longdate)

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. ThecontainsHeadermethod 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

public void addDateHeader(java.lang.Stringname,
                          longdate)

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

public void setHeader(java.lang.Stringname,
                      java.lang.Stringvalue)

Sets a response header with the given name and value. If the header had already been set, the new value overwrites the previous one. ThecontainsHeadermethod 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

public void addHeader(java.lang.Stringname,
                      java.lang.Stringvalue)

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

public void setIntHeader(java.lang.Stringname,
                         intvalue)

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. ThecontainsHeadermethod 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

public void addIntHeader(java.lang.Stringname,
                         intvalue)

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

public void setStatus(intsc)

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, thesendErrormethod should be used instead.

The container clears the buffer and sets the Location header, preserving cookies and other headers.

Parameters:

sc- the status code

See Also:

sendError(int, java.lang.String)

setStatus

public void setStatus(intsc,
                      java.lang.Stringsm)

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

Parameters:

sc- the status code

sm- the status message