javax.servlet.ServletResponse Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package javax.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Locale;
/**
* Defines an object to assist a servlet in sending a response to the client.
* The servlet container creates a 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 {@link ServletOutputStream} returned by {@link #getOutputStream}.
* To send character data, use the PrintWriter object
* returned by {@link #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 {@link #setCharacterEncoding} and
* {@link #setContentType} methods, or implicitly
* using the {@link #setLocale} 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.
*
* @version $Rev: 788194 $ $Date: 2009-06-24 18:05:48 -0400 (Wed, 24 Jun 2009) $
* @see ServletOutputStream
*/
public interface ServletResponse {
/**
* 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 #setBufferSize
* @see #getBufferSize
* @see #isCommitted
* @see #reset
*/
void flushBuffer() throws IOException;
/**
* Returns the actual buffer size used for the response. If no buffering
* is used, this method returns 0.
*
* @return the actual buffer size used
* @see #setBufferSize
* @see #flushBuffer
* @see #isCommitted
* @see #reset
*/
int getBufferSize();
/**
* 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 the {@link #setCharacterEncoding} or
* {@link #setContentType} methods, or implicitly using the
* {@link #setLocale} 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.
*
* @return a String specifying the
* name of the character encoding, for
* example, UTF-8
*/
String getCharacterEncoding();
/**
* Returns the content type used for the MIME body
* sent in this response. The content type proper must
* have been specified using {@link #setContentType}
* 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 {@link #getCharacterEncoding},
* the charset parameter is included in the string returned.
* If no character encoding has been specified, the
* charset parameter is omitted.
*
* @return a String specifying the
* content type, for example,
* text/html; charset=UTF-8,
* or null
* @since 2.4
*/
String getContentType();
/**
* Returns the locale specified for this response
* using the {@link #setLocale} 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.
*
* @return locale specified for this response
* @see #setLocale
*/
Locale getLocale();
/**
* Returns a {@link 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 {@link #getWriter} may
* be called to write the body, not both.
*
* @throws IllegalStateException if the getWriter method
* has been called on this response
* @throws IOException if an input or output exception occurred
* @return a {@link ServletOutputStream} for writing binary data
* @see #getWriter
*/
ServletOutputStream getOutputStream() throws IOException;
/**
* Returns a PrintWriter object that
* can send character text to the client.
* The PrintWriter uses the character
* encoding returned by {@link #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 {@link #getOutputStream} may be called
* to write the body, not both.
*
* @return a PrintWriter object that
* can return character data to the client
* @throws java.io.UnsupportedEncodingException
* if the character encoding returned
* by getCharacterEncoding cannot be used
* @throws IllegalStateException if the getOutputStream
* method has already been called for this
* response object
* @throws IOException if an input or output exception occurred
* @see #getOutputStream
* @see #setCharacterEncoding
*/
PrintWriter getWriter() throws IOException;
/**
* Returns a boolean indicating if the response has been
* committed. A committed response has already had its status
* code and headers written.
*
* @return a boolean indicating if the response has been
* committed
* @see #setBufferSize
* @see #getBufferSize
* @see #flushBuffer
* @see #reset
*/
boolean isCommitted();
/**
* 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 an
* IllegalStateException.
*
* @throws IllegalStateException if the response has already been
* committed
* @see #setBufferSize
* @see #getBufferSize
* @see #flushBuffer
* @see #isCommitted
*/
void reset();
/**
* 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 an
* IllegalStateException.
*
* @see #setBufferSize
* @see #getBufferSize
* @see #isCommitted
* @see #reset
* @since 2.3
*/
void resetBuffer();
/**
* 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
* using 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.
*
* @param size the preferred buffer size
* @throws IllegalStateException if this method is called after
* content has been written
* @see #getBufferSize
* @see #flushBuffer
* @see #isCommitted
* @see #reset
*/
void setBufferSize(int size);
/**
* 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 by
* {@link #setContentType} or {@link #setLocale},
* this method overrides it.
* Calling {@link #setContentType} 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.
*
* @param charset a String specifying only the character set
* defined by IANA Character Sets
* (http://www.iana.org/assignments/character-sets)
* @see #setContentType #setLocale
* @since 2.4
*/
void setCharacterEncoding(String charset);
/**
* Sets the length of the content body in the response
* In HTTP servlets, this method sets the HTTP Content-Length header.
*
* @param len an integer specifying the length of the
* content being returned to the client; sets
* the Content-Length header
*/
void setContentLength(int len);
/**
* 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 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.
*
* @param type a String specifying the MIME
* type of the content
* @see #setLocale
* @see #setCharacterEncoding
* @see #getOutputStream
* @see #getWriter
*/
void setContentType(String type);
/**
* 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 using {@link #setContentType} or
* {@link #setCharacterEncoding}, 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 {@link #setContentType}
* has been called with a charset specification, after
* {@link #setCharacterEncoding} 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.
*
* @param loc the locale of the response
* @see #getLocale
* @see #setContentType
* @see #setCharacterEncoding
*/
void setLocale(Locale loc);
}