jspwriter.java

This subproject contains the compiled code for the implementation classes of the Java Servlet and J

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
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 *    permission, please contact [e-mail].
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 * 5. Products derived from this software may not be called "Apache"
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 *
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */ 
 
package javax.servlet.jsp;

import java.io.IOException;

/**
 * <p>
 * The actions and template data in a JSP page is written using the
 * JspWriter object that is referenced by the implicit variable out which
 * is initialized automatically using methods in the PageContext object.
 *<p>
 * This abstract class emulates some of the functionality found in the
 * java.io.BufferedWriter and java.io.PrintWriter classes,
 * however it differs in that it throws java.io.IOException from the print
 * methods while PrintWriter does not.
 * <p><B>Buffering</B>
 * <p>
 * The initial JspWriter object is associated with the PrintWriter object
 * of the ServletResponse in a way that depends on whether the page is or
 * is not buffered. If the page is not buffered, output written to this
 * JspWriter object will be written through to the PrintWriter directly,
 * which will be created if necessary by invoking the getWriter() method
 * on the response object. But if the page is buffered, the PrintWriter
 * object will not be created until the buffer is flushed and
 * operations like setContentType() are legal. Since this flexibility
 * simplifies programming substantially, buffering is the default for JSP
 * pages.
 * <p>
 * Buffering raises the issue of what to do when the buffer is
 * exceeded. Two approaches can be taken:
 * <ul>
 * <li>
 * Exceeding the buffer is not a fatal error; when the buffer is
 * exceeded, just flush the output.
 * <li>
 * Exceeding the buffer is a fatal error; when the buffer is exceeded,
 * raise an exception.
 * </ul>
 * <p>
 * Both approaches are valid, and thus both are supported in the JSP
 * technology. The behavior of a page is controlled by the autoFlush
 * attribute, which defaults to true. In general, JSP pages that need to
 * be sure that correct and complete data has been sent to their client
 * may want to set autoFlush to false, with a typical case being that
 * where the client is an application itself. On the other hand, JSP
 * pages that send data that is meaningful even when partially
 * constructed may want to set autoFlush to true; such as when the
 * data is sent for immediate display through a browser. Each application
 * will need to consider their specific needs.
 * <p>
 * An alternative considered was to make the buffer size unbounded; but,
 * this had the disadvantage that runaway computations would consume an
 * unbounded amount of resources.
 * <p>
 * The "out" implicit variable of a JSP implementation class is of this type.
 * If the page directive selects autoflush="true" then all the I/O operations
 * on this class shall automatically flush the contents of the buffer if an
 * overflow condition would result if the current operation were performed
 * without a flush. If autoflush="false" then all the I/O operations on this
 * class shall throw an IOException if performing the current operation would
 * result in a buffer overflow condition.
 *
 * @see java.io.Writer
 * @see java.io.BufferedWriter
 * @see java.io.PrintWriter
 */

abstract public class JspWriter extends java.io.Writer {

    /**
     * Constant indicating that the Writer is not buffering output.
     */

    public static final int	NO_BUFFER = 0;

    /**
     * Constant indicating that the Writer is buffered and is using the
     * implementation default buffer size.
     */

    public static final int	DEFAULT_BUFFER = -1;

    /**
     * Constant indicating that the Writer is buffered and is unbounded; this
     * is used in BodyContent.
     */

    public static final int	UNBOUNDED_BUFFER = -2;

    /**
     * Protected constructor.
     *
     * @param bufferSize the size of the buffer to be used by the JspWriter
     * @param autoFlush whether the JspWriter should be autoflushing
     */

    protected JspWriter(int bufferSize, boolean autoFlush) {
	this.bufferSize = bufferSize;
	this.autoFlush  = autoFlush;
    }

    /**
     * Write a line separator.  The line separator string is defined by the
     * system property <tt>line.separator</tt>, and is not necessarily a single
     * newline ('\n') character.
     *
     * @exception  IOException  If an I/O error occurs
     */

    abstract public void newLine() throws IOException;

    /**
     * Print a boolean value.  The string produced by <code>{@link
     * java.lang.String#valueOf(boolean)}</code> is written to the
     * JspWriter's buffer or, if no buffer is used, directly to the 
     * underlying writer.
     *
     * @param      b   The <code>boolean</code> to be printed
     * @throws	   java.io.IOException If an error occured while writing
     */

    abstract public void print(boolean b) throws IOException;

    /**
     * Print a character.  The character is written to the
     * JspWriter's buffer or, if no buffer is used, directly to the
     * underlying writer.
     *
     * @param      c   The <code>char</code> to be printed
     * @throws	   java.io.IOException If an error occured while writing
     */

    abstract public void print(char c) throws IOException;

    /**
     * Print an integer.  The string produced by <code>{@link
     * java.lang.String#valueOf(int)}</code> is written to the
     * JspWriter's buffer or, if no buffer is used, directly to the
     * underlying writer.
     *
     * @param      i   The <code>int</code> to be printed
     * @see        java.lang.Integer#toString(int)
     * @throws	   java.io.IOException If an error occured while writing
     */

    abstract public void print(int i) throws IOException;

    /**
     * Print a long integer.  The string produced by <code>{@link
     * java.lang.String#valueOf(long)}</code> is written to the
     * JspWriter's buffer or, if no buffer is used, directly to the
     * underlying writer.
     *
     * @param      l   The <code>long</code> to be printed
     * @see        java.lang.Long#toString(long)
     * @throws	   java.io.IOException If an error occured while writing
     */

    abstract public void print(long l) throws IOException;

    /**
     * Print a floating-point number.  The string produced by <code>{@link
     * java.lang.String#valueOf(float)}</code> is written to the
     * JspWriter's buffer or, if no buffer is used, directly to the
     * underlying writer.
     *
     * @param      f   The <code>float</code> to be printed
     * @see        java.lang.Float#toString(float)
     * @throws	   java.io.IOException If an error occured while writing
     */

    abstract public void print(float f) throws IOException;

    /**
     * Print a double-precision floating-point number.  The string produced by
     * <code>{@link java.lang.String#valueOf(double)}</code> is written to
     * the JspWriter's buffer or, if no buffer is used, directly to the
     * underlying writer.
     *
     * @param      d   The <code>double</code> to be printed
     * @see        java.lang.Double#toString(double)
     * @throws	   java.io.IOException If an error occured while writing
     */

    abstract public void print(double d) throws IOException;

    /**