Interface ServletResponse
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- All Known Subinterfaces:
HttpServletResponse
- All Known Implementing Classes:
HttpServletResponseWrapper,ServletResponseWrapper
public interface ServletResponseDefines an object to assist a servlet in sending a response to the client. The servlet container creates aServletResponseobject and passes it as an argument to the servlet'sservicemethod.To send binary data in a MIME body response, use the
ServletOutputStreamreturned bygetOutputStream(). To send character data, use thePrintWriterobject returned bygetWriter(). To mix binary and text data, for example, to create a multipart response, use aServletOutputStreamand manage the character sections manually.The charset for the MIME body response can be specified explicitly using the
setCharacterEncoding(java.lang.String)andsetContentType(java.lang.String)methods, or implicitly using thesetLocale(java.util.Locale)method. Explicit specifications take precedence over implicit specifications. If no charset is specified, ISO-8859-1 will be used. ThesetCharacterEncoding,setContentType, orsetLocalemethod must be called beforegetWriterand 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.
- See Also:
ServletOutputStream
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description voidflushBuffer()Forces any content in the buffer to be written to the client.intgetBufferSize()Returns the actual buffer size used for the response.java.lang.StringgetCharacterEncoding()Returns the name of the character encoding (MIME charset) used for the body sent in this response.java.lang.StringgetContentType()Returns the content type used for the MIME body sent in this response.java.util.LocalegetLocale()Returns the locale specified for this response using thesetLocale(java.util.Locale)method.ServletOutputStreamgetOutputStream()Returns aServletOutputStreamsuitable for writing binary data in the response.java.io.PrintWritergetWriter()Returns aPrintWriterobject that can send character text to the client.booleanisCommitted()Returns a boolean indicating if the response has been committed.voidreset()Clears any data that exists in the buffer as well as the status code and headers.voidresetBuffer()Clears the content of the underlying buffer in the response without clearing headers or status code.voidsetBufferSize(int size)Sets the preferred buffer size for the body of the response.voidsetCharacterEncoding(java.lang.String charset)Sets the character encoding (MIME charset) of the response being sent to the client, for example, to UTF-8.voidsetContentLength(int len)Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.voidsetContentLengthLong(long length)Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.voidsetContentType(java.lang.String type)Sets the content type of the response being sent to the client, if the response has not been committed yet.voidsetLocale(java.util.Locale loc)Sets the locale of the response, if the response has not been committed yet.
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Method Detail
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getCharacterEncoding
java.lang.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(java.lang.String)orsetContentType(java.lang.String)methods, or implicitly using thesetLocale(java.util.Locale)method. Explicit specifications take precedence over implicit specifications. Calls made to these methods aftergetWriterhas been called or after the response has been committed have no effect on the character encoding. If no character encoding has been specified,ISO-8859-1is returned.See RFC 2047 (http://www.ietf.org/rfc/rfc2047.txt) for more information about character encoding and MIME.
- Returns:
- a
Stringspecifying the name of the character encoding, for example,UTF-8
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getContentType
java.lang.String getContentType()
Returns the content type used for the MIME body sent in this response. The content type proper must have been specified usingsetContentType(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 ingetCharacterEncoding(), the charset parameter is included in the string returned. If no character encoding has been specified, the charset parameter is omitted.- Returns:
- a
Stringspecifying the content type, for example,text/html; charset=UTF-8, or null - Since:
- Servlet 2.4
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getOutputStream
ServletOutputStream getOutputStream() throws java.io.IOException
Returns aServletOutputStreamsuitable 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.- Returns:
- a
ServletOutputStreamfor writing binary data - Throws:
java.lang.IllegalStateException- if thegetWritermethod has been called on this responsejava.io.IOException- if an input or output exception occurred- See Also:
getWriter()
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getWriter
java.io.PrintWriter getWriter() throws java.io.IOExceptionReturns aPrintWriterobject that can send character text to the client. ThePrintWriteruses 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),getWriterupdates it toISO-8859-1.Calling flush() on the
PrintWritercommits the response.Either this method or
getOutputStream()may be called to write the body, not both.- Returns:
- a
PrintWriterobject that can return character data to the client - Throws:
java.io.UnsupportedEncodingException- if the character encoding returned bygetCharacterEncodingcannot be usedjava.lang.IllegalStateException- if thegetOutputStreammethod has already been called for this response objectjava.io.IOException- if an input or output exception occurred- See Also:
getOutputStream(),setCharacterEncoding(java.lang.String)
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setCharacterEncoding
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. If the character encoding has already been set bysetContentType(java.lang.String)orsetLocale(java.util.Locale), this method overrides it. CallingsetContentType(java.lang.String)with theStringoftext/htmland calling this method with theStringofUTF-8is equivalent with callingsetContentTypewith theStringoftext/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
getWriterhas 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-Typeheader 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:
- Servlet 2.4
- See Also:
#setLocale
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setContentLength
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
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setContentLengthLong
void setContentLengthLong(long length)
Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.- Parameters:
length- an integer specifying the length of the content being returned to the client; sets the Content-Length header- Since:
- Servlet 3.1
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setContentType
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. 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 beforegetWriteris 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
getWriterhas 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-Typeheader is used.- Parameters:
type- aStringspecifying the MIME type of the content- See Also:
setLocale(java.util.Locale),setCharacterEncoding(java.lang.String),getOutputStream(),getWriter()
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setBufferSize
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 an
IllegalStateException.- Parameters:
size- the preferred buffer size- Throws:
java.lang.IllegalStateException- if this method is called after content has been written- See Also:
getBufferSize(),flushBuffer(),isCommitted(),reset()
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getBufferSize
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()
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flushBuffer
void flushBuffer() throws java.io.IOExceptionForces 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.- Throws:
java.io.IOException- if an I/O occurs during the flushing of the response- See Also:
setBufferSize(int),getBufferSize(),isCommitted(),reset()
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resetBuffer
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:
- Servlet 2.3
- See Also:
setBufferSize(int),getBufferSize(),isCommitted(),reset()
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isCommitted
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()
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reset
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.- Throws:
java.lang.IllegalStateException- if the response has already been committed- See Also:
setBufferSize(int),getBufferSize(),flushBuffer(),isCommitted()
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setLocale
void setLocale(java.util.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(java.lang.String)orsetCharacterEncoding(java.lang.String),getWriterhasn't been called yet, and the response hasn't been committed yet. If the deployment descriptor contains alocale-encoding-mapping-listelement, 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, aftersetCharacterEncoding(java.lang.String)has been called, aftergetWriterhas 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-Languageheader, the character encoding as part of theContent-Typeheader 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- See Also:
getLocale(),setContentType(java.lang.String),setCharacterEncoding(java.lang.String)
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getLocale
java.util.Locale getLocale()
Returns the locale specified for this response using thesetLocale(java.util.Locale)method. Calls made tosetLocaleafter the response is committed have no effect.- Returns:
- The locale specified for this response using the
setLocale(java.util.Locale)method. If no locale has been specified, the container's default locale is returned. - See Also:
setLocale(java.util.Locale)
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