libjava/classpath/gnu/java/beans/encoder/Writer.java

   1 /* Writer.java -- Writing interface for XML persistence.
   2  Copyright (C) 2005 Free Software Foundation, Inc.
   3
   4  This file is part of GNU Classpath.
   5
   6  GNU Classpath is free software; you can redistribute it and/or modify
   7  it under the terms of the GNU General Public License as published by
   8  the Free Software Foundation; either version 2, or (at your option)
   9  any later version.
  10
  11  GNU Classpath is distributed in the hope that it will be useful, but
  12  WITHOUT ANY WARRANTY; without even the implied warranty of
  13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  General Public License for more details.
  15
  16  You should have received a copy of the GNU General Public License
  17  along with GNU Classpath; see the file COPYING.  If not, write to the
  18  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19  02110-1301 USA.
  20
  21  Linking this library statically or dynamically with other modules is
  22  making a combined work based on this library.  Thus, the terms and
  23  conditions of the GNU General Public License cover the whole
  24  combination.
  25
  26  As a special exception, the copyright holders of this library give you
  27  permission to link this library with independent modules to produce an
  28  executable, regardless of the license terms of these independent
  29  modules, and to copy and distribute the resulting executable under
  30  terms of your choice, provided that you also meet, for each linked
  31  independent module, the terms and conditions of the license of that
  32  module.  An independent module is a module which is not derived from
  33  or based on this library.  If you modify this library, you may extend
  34  this exception to your version of the library, but you are not
  35  obligated to do so.  If you do not wish to do so, delete this
  36  exception statement from your version. */
  37
  38
  39 package gnu.java.beans.encoder;
  40
  41 /** A <code>Writer</code> represents a simplified interface to an XML
  42  * writer that is used for the XML persistence mechanism.
  43  *
  44  * <p>Its sole purpose is to allow multiple backends which may remove
  45  * the need to have certain APIs in the classpath. Eg. it is possible
  46  * to write a stripped down XML Writer that does not rely on SAX, StAX
  47  * or DOM APIs.</p>
  48  *
  49  * <p>The caller may assume that every action is done immediately. However
  50  * it is possible that the underlying implementation uses buffering streams.
  51  * To make sure the data is written call the {@link flush} method.</p>
  52  *
  53  * <p>The <code>Writer</code> implementation should care about the formatting
  54  * of the XML stream making it possible to generate three types of formats using
  55  * a special method invocation chain.</p>
  56  *
  57  * <p>Write
  58  * <code>
  59  * &lt;element/&gt;
  60  * </code>
  61  * by issuing <code>write("element", true)</code> (or any of the other
  62  * write-variants that allows specifying the <code>isEmpty</code> argument)
  63  * and <code>writeEnd(true)</code>.</p>
  64  *
  65  * <p>Write
  66  * <code>
  67  * &lt;element&gt;body&lt;/element&gt;
  68  * </code>
  69  * by issuing <code>writeNoChildren("element", "body")</code> and <code>writeNoChildrenEnd()</code>.</p>
  70  *
  71  * <p>
  72  * Write
  73  * <code>
  74  * &lt;element&gt;
  75  *   &lt;child1/&gt;
  76  *   &lt;child2/&gt;
  77  *   ...
  78  * &lt;element/&gt;
  79  * </code>
  80  * by issuing <code>write("element", false)</code> (or any of the other
  81  * write-variants that allows specifying the <code>isEmpty</code> argument)
  82  * and <code>writeEnd(false)</code>.</p>
  83  *
  84  * <p>Note: It is important that the values of <code>isEmpty</code> and
  85  * <code>wasEmpty</code> match. Otherwise strange things might happen to
  86  * the layout.</p>
  87  *
  88  * @author Robert Schuster (robertschuster@fsfe.org)
  89  *
  90  */
  91 public interface Writer
  92 {
  93   // TODO: This interface's design is not the best. Feel free to
  94   // improve it as you like.
  95
  96   /** Writes the XML preamble. */
  97   void writePreamble();
  98
  99   /** Writes the end of an XML tag.
 100    *
 101    * <p>If your tag has not generated any body text or child
 102    * elements provide <code>true</code> as the argument to generate
 103    * more space efficient variant of the tag.>/p>
 104    *
 105    * @param wasEmpty Whether the tag was empty or not.
 106    */
 107   void writeEnd(boolean wasEmpty);
 108
 109   /** Writes an XML tag without any attributes.
 110    *
 111    * @param tagName The name of the tag to write.
 112    * @param empty Whether the element has child elements.
 113    */
 114   void write(String tagName, boolean empty);
 115
 116   /** Writes an XML tag with one attribute name and value.
 117    *
 118    * @param tagName The name of the tag to write.
 119    * @param attributeName The name of attribute.
 120    * @param attributeValue The attribute's value.
 121    * @param empty Whether the element has child elements.
 122    */
 123   void write(String tagName, String attributeName, String attributeValue, boolean empty);
 124
 125   /** Writes an XML tag with multiple attributes and a body text.
 126    *
 127    * @param tagName The name of the tag to write.
 128    * @param value The element's body content.
 129    * @param attributeNames A set of attribute names.
 130    * @param attributeValues A set of attribute values.
 131    * @param empty Whether the element has child elements.
 132    */
 133   void write(String tagName, String value, String[] attributeNames,
 134              String[] attributeValues, boolean empty);
 135
 136   /** Writes an XML tag with multiple attributes without a body text.
 137    *
 138    * @param tagName The name of the tag to write.
 139    * @param attributeNames A set of attribute names.
 140    * @param attributeValues A set of attribute values.
 141    * @param empty Whether the element has child elements.
 142    */
 143   void write(String tagName, String[] attributeNames, String[] attributeValues, boolean empty);
 144
 145   /** Writes an XML tag with no attributes but with a body text
 146    * that may have child elements.
 147    *
 148    * @param tagName The name of the tag to write.
 149    * @param value The element's body content.
 150    */
 151   void write(String tagName, String value);
 152
 153   /** Writes an XML tag with no attributes but with a body text
 154    * that does not have child elements.
 155    *
 156    * @param tagName The name of the tag to write.
 157    * @param value The element's body content.
 158    */
 159   void writeNoChildren(String tagName, String value);
 160
 161   /** Writes the end of an XML tag that has no child elements.
 162    *
 163    * <p>Must be used in combination with {@link writeNoChildren} only.</p>
 164    */
 165   void writeEndNoChildren();
 166
 167   /** Forces the implementation to write some data.
 168    */
 169   void flush();
 170
 171   /** Closes the writer.
 172    */
 173   void close();
 174 }