javax.servlet.ServletResponse Maven / Gradle / Ivy
/*
* Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved.
* Copyright 2004 The Apache Software Foundation
*
* Licensed 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 any of the following techniques: per request, per web-app (using
* {@link ServletContext#setRequestCharacterEncoding}, deployment descriptor),
* and per container (for all web applications deployed in that container,
* using vendor specific configuration).
* If multiple of the preceding techniques have been employed, the priority is
* the order listed.
* For per request, the charset for the 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 explicitly 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.
*
* @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 following methods for specifying the response character encoding are
* consulted, in decreasing order of priority: per request, perweb-app
* (using {@link ServletContext#setResponseCharacterEncoding}, deployment
* descriptor), and per container (for all web applications deployed in
* that container, using vendor specific configuration).
* The first one of these methods that yields a result is returned.
* Per-request, the charset for the response can be specified explicitly
* using the {@link setCharacterEncoding} and {@link setContentType}
* 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.
*
* @return a String specifying the name of
* the character encoding, for example, UTF-8
*/
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}
* or {@link #getWriter} has been called,
* 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 Servlet 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.
*
*
Calling flush() on the ServletOutputStream commits the response.
*
* Either this method or {@link #getWriter} may
* be called to write the body, not both, except when {@link #reset}
* has been called.
*
* @return a {@link ServletOutputStream} for writing binary data
*
* @exception IllegalStateException if the getWriter method
* has been called on this response
*
* @exception IOException if an input or output exception occurred
*
* @see #getWriter
* @see #reset
*/
public 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, except when {@link #reset}
* has been called.
*
* @return a PrintWriter object that
* can return character data to the client
*
* @exception java.io.UnsupportedEncodingException
* if the character encoding returned
* by getCharacterEncoding cannot be used
*
* @exception IllegalStateException
* if the getOutputStream
* method has already been called for this response object
*
* @exception IOException
* if an input or output exception occurred
*
* @see #getOutputStream
* @see #setCharacterEncoding
* @see #reset
*/
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 response character encoding has already been set by the
* {@link ServletContext#setResponseCharacterEncoding},
* deployment descriptor, or using the setContentType() or setLocale()
* methods, the value set in this method overrides any of those values.
* 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
* @see #setLocale
*
* @since Servlet 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 length of the content body in the response
* In HTTP servlets, this method sets the HTTP Content-Length header.
*
* @param len a long specifying the length of the
* content being returned to the client; sets the Content-Length header
*
* @since Servlet 3.1
*/
public void setContentLengthLong(long 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
*
*/
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 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
*
* @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
* @throws IOException if the act of flushing the buffer cannot be
* completed.
*
*/
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
* IllegalStateException.
*
* @see #setBufferSize
* @see #getBufferSize
* @see #isCommitted
* @see #reset
*
* @since Servlet 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,
* headers. The state of calling {@link #getWriter} or
* {@link #getOutputStream} is also cleared. It is legal, for instance,
* to call {@link #getWriter}, {@link #reset} and then
* {@link #getOutputStream}. If {@link #getWriter} or
* {@link #getOutputStream} have been called before this method,
* then the corrresponding returned Writer or OutputStream will be
* staled and the behavior of using the stale object is undefined.
* If the response has been committed, this method throws an
* IllegalStateException.
*
* @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}, 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
*/
public void setLocale(Locale loc);
/**
* 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 the Locale for this response.
*
* @see #setLocale
*/
public Locale getLocale();
}