public interface ServletResponse
ServletResponse
object and
passes it as an argument to the servlet's service
method.
To send binary data in a MIME body response, use
the ServletOutputStream
returned by getOutputStream()
.
To send character data, use the PrintWriter
object
returned by getWriter()
. To mix binary and text data,
for example, to create a multipart response, use a
ServletOutputStream
and manage the character sections
manually.
The charset for the MIME body response can be specified explicitly
using any of the following techniques: per request, per web-app (using
ServletContext.setRequestCharacterEncoding(java.lang.String)
, deployment descriptor),
and per container (for all web applications deployed in that container,
using vendor specific configuration).
If multiple of the preceding techniques have been employed, the priority is
the order listed.
For per request, the charset for the response can be specified explicitly
using the setCharacterEncoding(java.lang.String)
and setContentType(java.lang.String)
methods,
or implicitly using the setLocale(java.util.Locale)
method.
Explicit specifications take precedence over implicit specifications.
If no charset is explicitly specified, ISO-8859-1 will be used.
The setCharacterEncoding
,
setContentType
, or setLocale
method must
be called before getWriter
and before committing
the response for the character encoding to be used.
See the Internet RFCs such as RFC 2045 for more information on MIME. Protocols such as SMTP and HTTP define profiles of MIME, and those standards are still evolving.
ServletOutputStream
Modifier and Type | Method and Description |
---|---|
void |
flushBuffer()
Forces any content in the buffer to be written to the client.
|
int |
getBufferSize()
Returns the actual buffer size used for the response.
|
String |
getCharacterEncoding()
Returns the name of the character encoding (MIME charset)
used for the body sent in this response.
|
String |
getContentType()
Returns the content type used for the MIME body
sent in this response.
|
Locale |
getLocale()
Returns the locale specified for this response
using the
setLocale(java.util.Locale) method. |
ServletOutputStream |
getOutputStream()
Returns a
ServletOutputStream suitable for writing binary
data in the response. |
PrintWriter |
getWriter()
Returns a
PrintWriter object that
can send character text to the client. |
boolean |
isCommitted()
Returns a boolean indicating if the response has been
committed.
|
void |
reset()
Clears any data that exists in the buffer as well as the status code,
headers.
|
void |
resetBuffer()
Clears the content of the underlying buffer in the response without
clearing headers or status code.
|
void |
setBufferSize(int size)
Sets the preferred buffer size for the body of the response.
|
void |
setCharacterEncoding(String charset)
Sets the character encoding (MIME charset) of the response
being sent to the client, for example, to UTF-8.
|
void |
setContentLength(int len)
Sets the length of the content body in the response
In HTTP servlets, this method sets the HTTP Content-Length header.
|
void |
setContentLengthLong(long len)
Sets the length of the content body in the response
In HTTP servlets, this method sets the HTTP Content-Length header.
|
void |
setContentType(String type)
Sets the content type of the response being sent to
the client, if the response has not been committed yet.
|
void |
setLocale(Locale loc)
Sets the locale of the response, if the response has not been
committed yet.
|
String getCharacterEncoding()
ServletContext.setResponseCharacterEncoding(java.lang.String)
, deployment
descriptor), and per container (for all web applications deployed in
that container, using vendor specific configuration).
The first one of these methods that yields a result is returned.
Per-request, the charset for the response can be specified explicitly
using the setCharacterEncoding
and setContentType
methods, or implicitly using the setLocale(java.util.Locale) method.
Explicit specifications take precedence over implicit specifications.
Calls made to these methods after getWriter
has been
called or after the response has been committed have no
effect on the character encoding. If no character encoding
has been specified, ISO-8859-1
is returned.
See RFC 2047 (http://www.ietf.org/rfc/rfc2047.txt) for more information about character encoding and MIME.
String
specifying the name of
the character encoding, for example, UTF-8
String getContentType()
setContentType(java.lang.String)
before the response is committed. If no content type
has been specified, this method returns null.
If a content type has been specified, and a
character encoding has been explicitly or implicitly
specified as described in getCharacterEncoding()
or getWriter()
has been called,
the charset parameter is included in the string returned.
If no character encoding has been specified, the
charset parameter is omitted.String
specifying the content type,
for example, text/html; charset=UTF-8
, or nullServletOutputStream getOutputStream() throws IOException
ServletOutputStream
suitable for writing binary
data in the response. The servlet container does not encode the
binary data.
Calling flush() on the ServletOutputStream commits the response.
Either this method or getWriter()
may
be called to write the body, not both, except when reset()
has been called.
ServletOutputStream
for writing binary dataIllegalStateException
- if the getWriter
method
has been called on this responseIOException
- if an input or output exception occurredgetWriter()
,
reset()
PrintWriter getWriter() throws IOException
PrintWriter
object that
can send character text to the client.
The PrintWriter
uses the character
encoding returned by getCharacterEncoding()
.
If the response's character encoding has not been
specified as described in getCharacterEncoding
(i.e., the method just returns the default value
ISO-8859-1
), getWriter
updates it to ISO-8859-1
.
Calling flush() on the PrintWriter
commits the response.
Either this method or getOutputStream()
may be called
to write the body, not both, except when reset()
has been called.
PrintWriter
object that
can return character data to the clientUnsupportedEncodingException
- if the character encoding returned
by getCharacterEncoding
cannot be usedIllegalStateException
- if the getOutputStream
method has already been called for this response objectIOException
- if an input or output exception occurredgetOutputStream()
,
setCharacterEncoding(java.lang.String)
,
reset()
void setCharacterEncoding(String charset)
ServletContext.setResponseCharacterEncoding(java.lang.String)
,
deployment descriptor, or using the setContentType() or setLocale()
methods, the value set in this method overrides any of those values.
Calling setContentType(java.lang.String)
with the String
of text/html
and calling
this method with the String
of UTF-8
is equivalent with calling
setContentType
with the String
of
text/html; charset=UTF-8
.
This method can be called repeatedly to change the character
encoding.
This method has no effect if it is called after
getWriter
has been
called or after the response has been committed.
Containers must communicate the character encoding used for
the servlet response's writer to the client if the protocol
provides a way for doing so. In the case of HTTP, the character
encoding is communicated as part of the Content-Type
header for text media types. Note that the character encoding
cannot be communicated via HTTP headers if the servlet does not
specify a content type; however, it is still used to encode text
written via the servlet response's writer.
charset
- a String specifying only the character set
defined by IANA Character Sets
(http://www.iana.org/assignments/character-sets)setContentType(java.lang.String)
,
setLocale(java.util.Locale)
void setContentLength(int len)
len
- an integer specifying the length of the
content being returned to the client; sets the Content-Length headervoid setContentLengthLong(long len)
len
- a long specifying the length of the
content being returned to the client; sets the Content-Length headervoid setContentType(String type)
text/html;charset=UTF-8
.
The response's character encoding is only set from the given
content type if this method is called before getWriter
is called.
This method may be called repeatedly to change content type and
character encoding.
This method has no effect if called after the response
has been committed. It does not set the response's character
encoding if it is called after getWriter
has been called or after the response has been committed.
Containers must communicate the content type and the character
encoding used for the servlet response's writer to the client if
the protocol provides a way for doing so. In the case of HTTP,
the Content-Type
header is used.
type
- a String
specifying the MIME
type of the contentsetLocale(java.util.Locale)
,
setCharacterEncoding(java.lang.String)
,
getOutputStream()
,
getWriter()
void setBufferSize(int size)
getBufferSize
.
A larger buffer allows more content to be written before anything is actually sent, thus providing the servlet with more time to set appropriate status codes and headers. A smaller buffer decreases server memory load and allows the client to start receiving data more quickly.
This method must be called before any response body content is
written; if content has been written or the response object has
been committed, this method throws an
IllegalStateException
.
size
- the preferred buffer sizeIllegalStateException
- if this method is called after
content has been writtengetBufferSize()
,
flushBuffer()
,
isCommitted()
,
reset()
int getBufferSize()
setBufferSize(int)
,
flushBuffer()
,
isCommitted()
,
reset()
void flushBuffer() throws IOException
IOException
- if the act of flushing the buffer cannot be
completed.setBufferSize(int)
,
getBufferSize()
,
isCommitted()
,
reset()
void resetBuffer()
IllegalStateException
.setBufferSize(int)
,
getBufferSize()
,
isCommitted()
,
reset()
boolean isCommitted()
setBufferSize(int)
,
getBufferSize()
,
flushBuffer()
,
reset()
void reset()
getWriter()
or
getOutputStream()
is also cleared. It is legal, for instance,
to call getWriter()
, reset()
and then
getOutputStream()
. If getWriter()
or
getOutputStream()
have been called before this method,
then the corrresponding returned Writer or OutputStream will be
staled and the behavior of using the stale object is undefined.
If the response has been committed, this method throws an
IllegalStateException
.IllegalStateException
- if the response has already been
committedsetBufferSize(int)
,
getBufferSize()
,
flushBuffer()
,
isCommitted()
void setLocale(Locale loc)
setContentType(java.lang.String)
or
setCharacterEncoding(java.lang.String)
, getWriter
hasn't
been called yet, and the response hasn't been committed yet.
If the deployment descriptor contains a
locale-encoding-mapping-list
element, and that
element provides a mapping for the given locale, that mapping
is used. Otherwise, the mapping from locale to character
encoding is container dependent.
This method may be called repeatedly to change locale and
character encoding. The method has no effect if called after the
response has been committed. It does not set the response's
character encoding if it is called after setContentType(java.lang.String)
has been called with a charset specification, after
setCharacterEncoding(java.lang.String)
has been called, after
getWriter
has been called, or after the response
has been committed.
Containers must communicate the locale and the character encoding
used for the servlet response's writer to the client if the protocol
provides a way for doing so. In the case of HTTP, the locale is
communicated via the Content-Language
header,
the character encoding as part of the Content-Type
header for text media types. Note that the character encoding
cannot be communicated via HTTP headers if the servlet does not
specify a content type; however, it is still used to encode text
written via the servlet response's writer.
loc
- the locale of the responsegetLocale()
,
setContentType(java.lang.String)
,
setCharacterEncoding(java.lang.String)
Locale getLocale()
setLocale(java.util.Locale)
method. Calls made to
setLocale
after the response is committed
have no effect. If no locale has been specified,
the container's default locale is returned.setLocale(java.util.Locale)
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