1 /*
   2  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.xml.internal.bind.v2.runtime.output;
  27 
  28 import java.io.IOException;
  29 
  30 import javax.xml.bind.JAXBContext;
  31 import javax.xml.stream.XMLStreamException;
  32 
  33 import com.sun.xml.internal.bind.v2.runtime.Name;
  34 import com.sun.xml.internal.bind.v2.runtime.NameList;
  35 import com.sun.xml.internal.bind.v2.runtime.XMLSerializer;
  36 
  37 import org.xml.sax.SAXException;
  38 
  39 /**
  40  * Well-formed XML writer.
  41  *
  42  * <p>
  43  * Implementations of this interface is used to connect {@link XMLSerializer}
  44  * to the actual target. This allows {@link XMLSerializer} to be API agnostic.
  45  *
  46  *
  47  * <h2>Notes</h2>
  48  * <p>
  49  * {@link JAXBContext} assigns indices to URIs and local names
  50  * that are statically known by using {@link NameList}.
  51  * {@link XmlOutput} implementation can use these indices to improve
  52  * the performance. For example, those namespace URI indices can be
  53  * turned into prefixes quickly.
  54  *
  55  * <p>
  56  * {@link XmlOutput} still allows arbitrary namepsace URIs / local names
  57  * to be written.
  58  *
  59  * <p>
  60  * The {@link NamespaceContextImpl} object, which is shared between {@link XmlOutput} and
  61  * {@link XMLSerializer}, keeps track of the in-scope namespace bindings. By the time
  62  * the {@link #beginStartTag} method is called, all the namespace bindings for the new
  63  * element is already declared. Similarly, after the {@link #endTag} method is called,
  64  * in-scope bindings will be removed. This book keeping is all done outside {@link XmlOutput}.
  65  *
  66  * <p>
  67  * {@link XmlOutput} and {@link XMLSerializer} uses indices to
  68  * reference prefixes/URIs to be written. {@link NamespaceContextImpl} can
  69  * convert prefix indices to URIs and the string representations of prefixes.
  70  * Binding from indices to URIs and prefixes do not change while indices
  71  * are "in scope", so {@link XmlOutput} is again expected to take advantage of
  72  * this to improve the perofmrnace.
  73  *
  74  * <p>
  75  * prefix index 0 is reserved for "xml", and this binding is assumed to be always there.
  76  * {@link NamespaceContextImpl} can handle this index correctly, but this binding will never
  77  * be reported to {@link XmlOutput} through {@link #beginStartTag}.
  78  *
  79  * <p>
  80  * One pecurilar behavior of a {@link NamespaceContextImpl} object is that it tries
  81  * to define redundant xmlns="" on the root element. Implementations of {@link XmlOutput}
  82  * is encouraged to check for this and avoid generating redundant namespace declarations.
  83  *
  84  *
  85  *
  86  * <h2>Call Sequence</h2>
  87  * <p>
  88  * {@link XMLSerializer} calls the writer methods in the following order:
  89  *
  90  * <pre>
  91  * CALLSEQUENCE  :=  {@link #startDocument startDocument} ELEMENT {@link #endDocument endDocument}
  92  *               |   ELEMENT   // for fragment
  93  *
  94  * ELEMENT       :=  {@link #beginStartTag beginStartTag} {@link #attribute attribute}* {@link #endStartTag endStartTag} CONTENTS {@link #endTag endTag}
  95  *
  96  * CONTENTS      :=  (ELEMENT | {@link #text text})*
  97  * </pre>
  98  *
  99  * TODO: for FI, consider making attribute values from Strings to CharSequences.
 100  *
 101  * @author Kohsuke Kawaguchi
 102  */
 103 public interface XmlOutput {
 104 //
 105 //
 106 // Contracts
 107 //
 108 //
 109     /**
 110      * Called at the very beginning.
 111      *
 112      * @param serializer
 113      *      the {@link XMLSerializer} that coordinates this whole marshalling episode.
 114      * @param fragment
 115      *      true if we are marshalling a fragment.
 116      */
 117     public void startDocument(XMLSerializer serializer, boolean fragment, int[] nsUriIndex2prefixIndex, NamespaceContextImpl nsContext) throws IOException, SAXException, XMLStreamException;
 118 
 119     /**
 120      * Called at the very end. This is the last method to be invoked.
 121      *
 122      * @param fragment
 123      *      false if we are writing the whole document.
 124      */
 125     public void endDocument(boolean fragment) throws IOException, SAXException, XMLStreamException;
 126 
 127     /**
 128      * Writes a start tag.
 129      *
 130      * <p>
 131      * At this point {@link NamespaceContextImpl} holds namespace declarations needed for this
 132      * new element.
 133      *
 134      * <p>
 135      * This method is used for writing tags that are indexed.
 136      */
 137     public void beginStartTag(Name name) throws IOException, XMLStreamException;
 138 
 139     public void beginStartTag(int prefix, String localName) throws IOException, XMLStreamException;
 140 
 141     public void attribute( Name name, String value ) throws IOException, XMLStreamException;
 142 
 143     /**
 144      * @param prefix
 145      *      -1 if this attribute does not have a prefix
 146      *      (this handling differs from that of elements.)
 147      */
 148     public void attribute( int prefix, String localName, String value ) throws IOException, XMLStreamException;
 149 
 150     public void endStartTag() throws IOException, SAXException;
 151 
 152     public void endTag(Name name) throws IOException, SAXException, XMLStreamException;
 153 
 154     public void endTag(int prefix, String localName) throws IOException, SAXException, XMLStreamException;
 155 
 156     /**
 157      * Writes XML text with character escaping, if necessary.
 158      *
 159      * @param value
 160      *      this string can contain characters that might need escaping
 161      *      (such as '&amp;' or '>')
 162      * @param needsSeparatingWhitespace
 163      */
 164     public void text( String value, boolean needsSeparatingWhitespace ) throws IOException, SAXException, XMLStreamException;
 165 
 166     /**
 167      * Writes XML text with character escaping, if necessary.
 168      *
 169      * @param value
 170      *      this string can contain characters that might need escaping
 171      *      (such as '&amp;' or '>')
 172      * @param needsSeparatingWhitespace
 173      */
 174     public void text( Pcdata value, boolean needsSeparatingWhitespace ) throws IOException, SAXException, XMLStreamException;
 175 }
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