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 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 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.
|
java.lang.String |
getCharacterEncoding()
Returns the name of the character encoding (MIME charset) used for the
body sent in this response.
|
java.lang.String |
getContentType()
Returns the content type used for the MIME body sent in this response.
|
java.util.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. |
java.io.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 and
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(java.lang.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 |
setContentType(java.lang.String type)
Sets the content type of the response being sent to the client, if the
response has not been committed yet.
|
void |
setLocale(java.util.Locale loc)
Sets the locale of the response, if the response has not been committed
yet.
|
java.lang.String getCharacterEncoding()
setCharacterEncoding(java.lang.String)
or
setContentType(java.lang.String)
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
java.lang.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()
, 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 java.io.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.
ServletOutputStream
for writing binary datajava.lang.IllegalStateException
- if the getWriter
method has been called on
this responsejava.io.IOException
- if an input or output exception occurredgetWriter()
java.io.PrintWriter getWriter() throws java.io.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.
PrintWriter
object that can return character data
to the clientjava.io.UnsupportedEncodingException
- if the character encoding returned by
getCharacterEncoding
cannot be usedjava.lang.IllegalStateException
- if the getOutputStream
method has already
been called for this response objectjava.io.IOException
- if an input or output exception occurredgetOutputStream()
,
setCharacterEncoding(java.lang.String)
void setCharacterEncoding(java.lang.String charset)
setContentType(java.lang.String)
or setLocale(java.util.Locale)
, this method
overrides it. 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)#setLocale
void setContentLength(int len)
len
- an integer specifying the length of the content being returned
to the client; sets the Content-Length headervoid setContentType(java.lang.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 sizejava.lang.IllegalStateException
- if this method is called after content has been writtengetBufferSize()
,
flushBuffer()
,
isCommitted()
,
reset()
int getBufferSize()
setBufferSize(int)
,
flushBuffer()
,
isCommitted()
,
reset()
void flushBuffer() throws java.io.IOException
java.io.IOException
- if an I/O occurs during the flushing of the responsesetBufferSize(int)
,
getBufferSize()
,
isCommitted()
,
reset()
void resetBuffer()
IllegalStateException
.setBufferSize(int)
,
getBufferSize()
,
isCommitted()
,
reset()
boolean isCommitted()
setBufferSize(int)
,
getBufferSize()
,
flushBuffer()
,
reset()
void reset()
IllegalStateException
.java.lang.IllegalStateException
- if the response has already been committedsetBufferSize(int)
,
getBufferSize()
,
flushBuffer()
,
isCommitted()
void setLocale(java.util.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)
java.util.Locale getLocale()
setLocale(java.util.Locale)
method. Calls made to setLocale
after the
response is committed have no effect.setLocale(java.util.Locale)
method. If no locale has been specified, the
container's default locale is returned.setLocale(java.util.Locale)
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