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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(String)
and
setContentType(String)
methods, or implicitly
using the setLocale(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
Method Summary | |
void |
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int |
|
String |
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String |
|
Locale |
|
ServletOutputStream |
|
PrintWriter |
|
boolean |
|
void |
|
void |
|
void |
|
void |
|
void |
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void |
|
void |
|
public void flushBuffer() throws IOException
Forces any content in the buffer to be written to the client. A call to this method automatically commits the response, meaning the status code and headers will be written.
- See Also:
setBufferSize(int)
,getBufferSize()
,isCommitted()
,reset()
public int getBufferSize()
Returns the actual buffer size used for the response. If no buffering is used, this method returns 0.
- Returns:
- the actual buffer size used
- See Also:
setBufferSize(int)
,flushBuffer()
,isCommitted()
,reset()
public String getCharacterEncoding()
Returns the name of the character encoding (MIME charset) used for the body sent in this response. The character encoding may have been specified explicitly using thesetCharacterEncoding(String)
orsetContentType(String)
methods, or implicitly using thesetLocale(Locale)
method. Explicit specifications take precedence over implicit specifications. Calls made to these methods aftergetWriter
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.
- Returns:
- a
String
specifying the name of the character encoding, for example,UTF-8
public String getContentType()
Returns the content type used for the MIME body sent in this response. The content type proper must have been specified usingsetContentType(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 ingetCharacterEncoding()
, the charset parameter is included in the string returned. If no character encoding has been specified, the charset parameter is omitted.
- Returns:
- a
String
specifying the content type, for example,text/html; charset=UTF-8
, or null
- Since:
- 2.4
public Locale getLocale()
Returns the locale specified for this response using thesetLocale(Locale)
method. Calls made tosetLocale
after the response is committed have no effect. If no locale has been specified, the container's default locale is returned.
- See Also:
setLocale(Locale)
public ServletOutputStream getOutputStream() throws IOException
Returns aServletOutputStream
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 orgetWriter()
may be called to write the body, not both.
- Returns:
- a
ServletOutputStream
for writing binary data
- See Also:
getWriter()
public PrintWriter getWriter() throws IOException
Returns aPrintWriter
object that can send character text to the client. ThePrintWriter
uses the character encoding returned bygetCharacterEncoding()
. If the response's character encoding has not been specified as described ingetCharacterEncoding
(i.e., the method just returns the default valueISO-8859-1
),getWriter
updates it toISO-8859-1
. Calling flush() on thePrintWriter
commits the response. Either this method orgetOutputStream()
may be called to write the body, not both.
- Returns:
- a
PrintWriter
object that can return character data to the client
public boolean isCommitted()
Returns a boolean indicating if the response has been committed. A committed response has already had its status code and headers written.
- Returns:
- a boolean indicating if the response has been committed
- See Also:
setBufferSize(int)
,getBufferSize()
,flushBuffer()
,reset()
public void reset()
Clears any data that exists in the buffer as well as the status code and headers. If the response has been committed, this method throws anIllegalStateException
.
- See Also:
setBufferSize(int)
,getBufferSize()
,flushBuffer()
,isCommitted()
public void resetBuffer()
Clears the content of the underlying buffer in the response without clearing headers or status code. If the response has been committed, this method throws anIllegalStateException
.
- Since:
- 2.3
- See Also:
setBufferSize(int)
,getBufferSize()
,isCommitted()
,reset()
public void setBufferSize(int size)
Sets the preferred buffer size for the body of the response. The servlet container will use a buffer at least as large as the size requested. The actual buffer size used can be found usinggetBufferSize
. 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 anIllegalStateException
.
- Parameters:
size
- the preferred buffer size
- See Also:
getBufferSize()
,flushBuffer()
,isCommitted()
,reset()
public void setCharacterEncoding(String charset)
Sets the character encoding (MIME charset) of the response being sent to the client, for example, to UTF-8. If the character encoding has already been set bysetContentType(String)
orsetLocale(Locale)
, this method overrides it. CallingsetContentType(String)
with theString
oftext/html
and calling this method with theString
ofUTF-8
is equivalent with callingsetContentType
with theString
oftext/html; charset=UTF-8
. This method can be called repeatedly to change the character encoding. This method has no effect if it is called aftergetWriter
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 theContent-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.
- Parameters:
charset
- a String specifying only the character set defined by IANA Character Sets (http://www.iana.org/assignments/character-sets)
- Since:
- 2.4
- See Also:
#setLocale
public 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.
- Parameters:
len
- an integer specifying the length of the content being returned to the client; sets the Content-Length header
public void setContentType(String type)
Sets the content type of the response being sent to the client, if the response has not been committed yet. The given content type may include a character encoding specification, for example,text/html;charset=UTF-8
. The response's character encoding is only set from the given content type if this method is called beforegetWriter
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 aftergetWriter
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, theContent-Type
header is used.
- Parameters:
type
- aString
specifying the MIME type of the content
public void setLocale(Locale loc)
Sets the locale of the response, if the response has not been committed yet. It also sets the response's character encoding appropriately for the locale, if the character encoding has not been explicitly set usingsetContentType(String)
orsetCharacterEncoding(String)
,getWriter
hasn't been called yet, and the response hasn't been committed yet. If the deployment descriptor contains alocale-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 aftersetContentType(String)
has been called with a charset specification, aftersetCharacterEncoding(String)
has been called, aftergetWriter
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 theContent-Language
header, the character encoding as part of theContent-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.
- Parameters:
loc
- the locale of the response