Tomcat example source code file (ServletResponse.java)

This example Tomcat source code file (ServletResponse.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

io, ioexception, ioexception, locale, printwriter, printwriter, servletoutputstream, servletoutputstream, servletresponse, string, string, util

The Tomcat ServletResponse.java source code

/*
* 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 object and
 * passes it as an argument to the servlet's <code>service 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 object 
 * returned by {@link #getWriter}. To mix binary and text data,
 * for example, to create a multipart response, use a
 * <code>ServletOutputStream 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>setContentType, or setLocale method must
 * be called before <code>getWriter 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
 * @version 	$Version$
 *
 * @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 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 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 specifying the
     *			name of the character encoding, for
     *			example, <code>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},
     * 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 specifying the
     *			content type, for example,
     *			<code>text/html; charset=UTF-8,
     *			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 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 object that
     * can send character text to the client.
     * The <code>PrintWriter uses the character
     * encoding returned by {@link #getCharacterEncoding}.
     * If the response's character encoding has not been
     * specified as described in <code>getCharacterEncoding
     * (i.e., the method just returns the default value 
     * <code>ISO-8859-1), getWriter
     * updates it to <code>ISO-8859-1.
     * <p>Calling flush() on the PrintWriter
     * commits the response.
     * <p>Either this method or {@link #getOutputStream} may be called
     * to write the body, not both.
     *
     * 
     * @return 		a <code>PrintWriter object that 
     *			can return character data to the client 
     *
     * @exception UnsupportedEncodingException
     *			if the character encoding returned
     *			by <code>getCharacterEncoding cannot be used
     *
     * @exception IllegalStateException
     *			if the <code>getOutputStream
     * 			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
     * of <code>text/html and calling
     * this method with the <code>String of UTF-8
     * is equivalent with calling
     * <code>setContentType with the String of
     * <code>text/html; charset=UTF-8.
     * <p>This method can be called repeatedly to change the character
     * encoding.
     * This method has no effect if it is called after
     * <code>getWriter 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
     * 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.
     * The response's character encoding is only set from the given
     * content type if this method is called before <code>getWriter
     * 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
     * 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 header is used.
     *
     * @param type 	a <code>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 <code>getBufferSize.
     *
     * <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.
     *
     * @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.
     *
     * @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.
     *
     * @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 hasn't
     * been called yet, and the response hasn't been committed yet.
     * If the deployment descriptor contains a 
     * <code>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.
     * <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 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 header,
     * the character encoding as part of the <code>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
     * <code>setLocale 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();



}