/*
* 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 <code>ServletResponse</code> object and
* passes it as an argument to the servlet's <code>service</code> method.
* <p>
* To send binary data in a MIME body response, use the
* {@link ServletOutputStream} returned by {@link #getOutputStream}. To send
* character data, use the <code>PrintWriter</code> object returned by
* {@link #getWriter}. To mix binary and text data, for example, to create a
* multipart response, use a <code>ServletOutputStream</code> and manage the
* character sections manually.
* <p>
* 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 <code>setCharacterEncoding</code>,
* <code>setContentType</code>, or <code>setLocale</code> method must be called
* before <code>getWriter</code> and before committing the response for the
* character encoding to be used.
* <p>
* See the Internet RFCs such as <a href="http://www.ietf.org/rfc/rfc2045.txt">
* RFC 2045</a> for more information on MIME. Protocols such as SMTP and HTTP
* define profiles of MIME, and those standards are still evolving.
*
* @author Various
* @see ServletOutputStream
*/
public interface ServletResponse {
/**
* 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
* <code>getWriter</code> has been called or after the response has been
* committed have no effect on the character encoding. If no character
* encoding has been specified, <code>ISO-8859-1</code> is returned.
* <p>
* See RFC 2047 (http://www.ietf.org/rfc/rfc2047.txt) for more information
* about character encoding and MIME.
*
* @return a <code>String</code> specifying the name of the character
* encoding, for example, <code>UTF-8</code>
*/
public 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 <code>String</code> specifying the content type, for example,
* <code>text/html; charset=UTF-8</code>, or null
* @since 2.4
*/
public String getContentType();
/**
* Returns a {@link ServletOutputStream} suitable for writing binary data in
* the response. The servlet container does not encode the binary data.
* <p>
* Calling flush() on the ServletOutputStream commits the response. Either
* this method or {@link #getWriter} may be called to write the body, not
* both.
*
* @return a {@link ServletOutputStream} for writing binary data
* @exception IllegalStateException
* if the <code>getWriter</code> method has been called on
* this response
* @exception IOException
* if an input or output exception occurred
* @see #getWriter
*/
public ServletOutputStream getOutputStream() throws IOException;
/**
* Returns a <code>PrintWriter</code> object that can send character text to
* the client. The <code>PrintWriter</code> uses the character encoding
* returned by {@link #getCharacterEncoding}. If the response's character
* encoding has not been specified as described in
* <code>getCharacterEncoding</code> (i.e., the method just returns the
* default value <code>ISO-8859-1</code>), <code>getWriter</code> updates it
* to <code>ISO-8859-1</code>.
* <p>
* Calling flush() on the <code>PrintWriter</code> commits the response.
* <p>
* Either this method or {@link #getOutputStream} may be called to write the
* body, not both.
*
* @return a <code>PrintWriter</code> object that can return character data
* to the client
* @exception java.io.UnsupportedEncodingException
* if the character encoding returned by
* <code>getCharacterEncoding</code> cannot be used
* @exception IllegalStateException
* if the <code>getOutputStream</code> method has already
* been called for this response object
* @exception IOException
* if an input or output exception occurred
* @see #getOutputStream
* @see #setCharacterEncoding
*/
public PrintWriter getWriter() throws IOException;
/**
* 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
* <code>String</code> of <code>text/html</code> and calling this method
* with the <code>String</code> of <code>UTF-8</code> is equivalent with
* calling <code>setContentType</code> with the <code>String</code> of
* <code>text/html; charset=UTF-8</code>.
* <p>
* This method can be called repeatedly to change the character encoding.
* This method has no effect if it is called after <code>getWriter</code>
* has been called or after the response has been committed.
* <p>
* 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 <code>Content-Type</code> 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
*/
public 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
*/
public 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,
* <code>text/html;charset=UTF-8</code>. The response's character encoding
* is only set from the given content type if this method is called before
* <code>getWriter</code> is called.
* <p>
* 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 <code>getWriter</code> has been called or after the response
* has been committed.
* <p>
* 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
* <code>Content-Type</code> header is used.
*
* @param type
* a <code>String</code> specifying the MIME type of the content
* @see #setLocale
* @see #setCharacterEncoding
* @see #getOutputStream
* @see #getWriter
*/
public void setContentType(String type);
/**
* 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 <code>getBufferSize</code>.
* <p>
* 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.
* <p>
* 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 <code>IllegalStateException</code>.
*
* @param size
* the preferred buffer size
* @exception IllegalStateException
* if this method is called after content has been written
* @see #getBufferSize
* @see #flushBuffer
* @see #isCommitted
* @see #reset
*/
public void setBufferSize(int size);
/**
* 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
*/
public int getBufferSize();
/**
* 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
*/
public void flushBuffer() throws IOException;
/**
* 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 <code>IllegalStateException</code>.
*
* @see #setBufferSize
* @see #getBufferSize
* @see #isCommitted
* @see #reset
* @since 2.3
*/
public void resetBuffer();
/**
* 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
*/
public 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
* <code>IllegalStateException</code>.
*
* @exception IllegalStateException
* if the response has already been committed
* @see #setBufferSize
* @see #getBufferSize
* @see #flushBuffer
* @see #isCommitted
*/
public void reset();
/**
* 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},
* <code>getWriter</code> hasn't been called yet, and the response hasn't
* been committed yet. If the deployment descriptor contains a
* <code>locale-encoding-mapping-list</code> 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.
* <p>
* 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
* <code>getWriter</code> has been called, or after the response has been
* committed.
* <p>
* 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 <code>Content-Language</code> header, the character encoding as part
* of the <code>Content-Type</code> 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
*/
public void setLocale(Locale loc);
/**
* Returns the locale specified for this response using the
* {@link #setLocale} method. Calls made to <code>setLocale</code> after the
* response is committed have no effect. If no locale has been specified,
* the container's default locale is returned.
*
* @see #setLocale
*/
public Locale getLocale();
}