From cf26925a572ce28eca6b8afb48c1a13c7f913a15 Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Thu, 10 Apr 2014 23:33:16 +0200
Subject: [PATCH] element lists
---
Doc/course.xml | 237 +++++++++++++++---
.../Jdbc/src/main/java/sax/count/Driver.java | 34 +++
.../java/sax/count/ListTagNamesHandler.java | 35 +++
3 files changed, 270 insertions(+), 36 deletions(-)
create mode 100644 ws/eclipse/Jdbc/src/main/java/sax/count/Driver.java
create mode 100644 ws/eclipse/Jdbc/src/main/java/sax/count/ListTagNamesHandler.java
diff --git a/Doc/course.xml b/Doc/course.xml
index 811c61c74..fba191e37 100644
--- a/Doc/course.xml
+++ b/Doc/course.xml
@@ -7666,8 +7666,8 @@ public class ElementCount {
redefine only those methods corresponding to events actually being
handled by the application in question.</para>
- <qandaset defaultlabel="qanda" xml:id="exercise_saxAttrib">
- <title>Reading XML attributes</title>
+ <qandaset xml:id="sda1SaxReadAttributes">
+ <title>SAX and attribute values</title>
<qandadiv>
<qandaentry>
@@ -7703,19 +7703,183 @@ public class AttribEventHandler extends DefaultHandler {
}</programlisting>
</answer>
</qandaentry>
+ </qandadiv>
+ </qandaset>
- <qandaentry xml:id="saxRdbms">
+ <qandaset xml:id="sda1QandaElementNames">
+ <title>Element lists of arbitrary XML documents.</title>
+
+ <qandadiv>
+ <qandaentry>
<question>
- <label>SAX processing with RDBMS access.</label>
+ <para>We reconsider the simple application reading arbitrary
+ XML documents and providing a list of XML Elements being
+ contained within:</para>
- <para>Implement the example given in <xref
- linkend="saxRdbmsAccessPrinciple"/> to produce the output
- sketched in <xref linkend="saxPriceOut"/>. You may start by
- implementing <emphasis>and testing</emphasis> the following
- methods of a RDBMS interfacing class using <trademark
- xlink:href="http://electronics.zibb.com/trademark/jdbc/29545026">JDBC</trademark>:</para>
+ <programlisting>Opening Document
+<emphasis role="bold">Opening "catalog"</emphasis>
+Content "
+ "
+<emphasis role="bold">Opening "item"</emphasis>
+Content "Swinging headset"
+Closing "item"
+Content " ...</programlisting>
+
+ <para>If an element like e.g. <tag
+ class="starttag">item</tag> appears multiple times it will
+ also be written to standard output multiple times.</para>
+
+ <para>We are now interested to get the list of all elements
+ names being present in an arbitrary XML document. Consider
+ the following example:</para>
+
+ <programlisting language="xml"><memo>
+ <from>
+ <name>Martin</name>
+ <surname>Goik</surname>
+ </from>
+ <to>
+ <name>Adam</name>
+ <surname>Hacker</surname>
+ </to>
+ <to>
+ <name>Eve</name>
+ <surname>Intruder</surname>
+ </to>
+ <date year="2005" month="1" day="6"/>
+ <subject>Firewall problems</subject>
+ <content>
+ <para>Thanks for your excellent work.</para>
+ <para>Our firewall is definitely broken!</para>
+ </content>
+</memo></programlisting>
+
+ <para>The elements <tag class="starttag">to</tag> , <tag
+ class="starttag">name</tag>, <tag
+ class="starttag">surname</tag> and <tag
+ class="starttag">para</tag> both appear multiple times.
+ Write a SAX application which processes arbitrary XML
+ documents and creates an alphabetically sorted list of
+ elements being contained <emphasis role="bold">excluding
+ duplicates</emphasis>. The intended output for the above
+ example is: </para>
+
+ <programlisting>List of elements: {content date from memo name para subject surname to }</programlisting>
+
+ <para>The corresponding handler should be implemented in a
+ re-usable way. Thus if different XML documents are being
+ handled in succession the list of elements should be erased
+ prior to processing the current document. Hints:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Use a <classname>java.util.SortedSet</classname>
+ instance to collect element names thereby excluding
+ duplicates.</para>
+ </listitem>
+
+ <listitem>
+ <para>The method
+ <methodname>sax.count.ListTagNamesHandler.startDocument()</methodname>
+ may be used to initialize your handler.</para>
+ </listitem>
+ </itemizedlist>
+ </question>
+
+ <answer>
+ <para>A suitable handler reads:</para>
+
+ <programlisting language="java">package sax.count;
+
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+import org.xml.sax.Attributes;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.DefaultHandler;
+
+/** Reading attributes from element events */
+public class ListTagNamesHandler extends DefaultHandler {
- <programlisting language="java">package sax.rdbms;
+ // A SortedSet by definition does not contain any duplicates.
+ private SortedSet<String> elementNames = new TreeSet<>();
+
+ @Override
+ public void startDocument() throws SAXException {
+ elementNames.clear(); // May contain elements from a previous run.
+ }
+
+ public void startElement(String namespaceUri, String localName,
+ String rawName, Attributes attrs) {
+ // In case the current element name has already been inserted
+ // this method call will be silently ignored.
+ elementNames.add(rawName);
+ }
+
+ /**
+ * @return A sorted list of element names of he currently processed XML
+ * document without duplicates.
+ */
+ public String[] getTagNames() {
+ return elementNames.toArray(new String[0]);
+ }
+}</programlisting>
+
+ <para>A complete application requires a driver:</para>
+
+ <programlisting language="java">package sax.count;
+
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+import org.xml.sax.XMLReader;
+
+import sax.stat.v2.MyErrorHandler;
+
+public class Driver {
+
+ public static void main(String argv[]) throws Exception {
+
+ final SAXParserFactory saxPf = SAXParserFactory.newInstance();
+ final SAXParser saxParser = saxPf.newSAXParser();
+ final XMLReader xmlReader = saxParser.getXMLReader();
+ final ListTagNamesHandler handler = new ListTagNamesHandler();
+ xmlReader.setContentHandler(handler);
+ xmlReader.setErrorHandler(new MyErrorHandler());
+ xmlReader.parse("Input/Xml/Memo/message.xml");
+
+ System.out.print("List of elements: {");
+ for (String elementName : handler.getTagNames()) {
+ System.out.print(elementName + " ");
+ }
+ System.out.println("}");
+ }
+}</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+
+ <section xml:id="sda1SaxRdbms">
+ <title>SAX and RDBMS</title>
+
+ <qandaset defaultlabel="qanda" xml:id="exercise_saxAttrib">
+ <title>Reading XML attributes</title>
+
+ <qandadiv>
+ <qandaentry xml:id="saxRdbms">
+ <question>
+ <label>SAX processing with RDBMS access.</label>
+
+ <para>Implement the example given in <xref
+ linkend="saxRdbmsAccessPrinciple"/> to produce the output
+ sketched in <xref linkend="saxPriceOut"/>. You may start
+ by implementing <emphasis>and testing</emphasis> the
+ following methods of a RDBMS interfacing class using
+ <trademark
+ xlink:href="http://electronics.zibb.com/trademark/jdbc/29545026">JDBC</trademark>:</para>
+
+ <programlisting language="java">package sax.rdbms;
public class RdbmsAccess {
@@ -7731,30 +7895,30 @@ public class RdbmsAccess {
}
}</programlisting>
- <para>You may find it helpful to write a small testbed for
- the RDBMS access functionality prior to integrate it into
- your <acronym
- xlink:href="http://www.saxproject.org">SAX</acronym>
- application producing HTML output.</para>
- </question>
+ <para>You may find it helpful to write a small testbed for
+ the RDBMS access functionality prior to integrate it into
+ your <acronym
+ xlink:href="http://www.saxproject.org">SAX</acronym>
+ application producing HTML output.</para>
+ </question>
- <answer>
- <para>We start by creating a suitable RDBMS Table:</para>
+ <answer>
+ <para>We start by creating a suitable RDBMS Table:</para>
- <programlisting>CREATE SCHEMA AUTHORIZATION midb2
+ <programlisting>CREATE SCHEMA AUTHORIZATION midb2
CREATE TABLE Product(
orderNo CHAR(10) NOT NULL PRIMARY KEY
,price DECIMAL (9,2) NOT NULL
)</programlisting>
- <para>Next we feed some toy data:</para>
+ <para>Next we feed some toy data:</para>
- <programlisting>INSERT INTO Product VALUES('x-223', 330.20);
+ <programlisting>INSERT INTO Product VALUES('x-223', 330.20);
INSERT INTO Product VALUES('w-124', 110.40);</programlisting>
- <para>Now we implement our RDBMS access class:</para>
+ <para>Now we implement our RDBMS access class:</para>
- <programlisting language="java">package dom.xsl;
+ <programlisting language="java">package dom.xsl;
...
public class DbAccess {
@@ -7797,10 +7961,10 @@ public class DbAccess {
private Connection conn = null;
}</programlisting>
- <para>This access layer may be tested independently from
- handling catalog instances:</para>
+ <para>This access layer may be tested independently from
+ handling catalog instances:</para>
- <programlisting language="java">package dom/xsl;
+ <programlisting language="java">package dom/xsl;
public class DbAccessDriver {
@@ -7814,12 +7978,12 @@ public class DbAccessDriver {
}
}</programlisting>
- <para>If the above test succeeds we may embed the RDBMS
- access layer into our The <acronym
- xlink:href="http://www.saxproject.org">SAX</acronym>
- handler:</para>
+ <para>If the above test succeeds we may embed the RDBMS
+ access layer into our The <acronym
+ xlink:href="http://www.saxproject.org">SAX</acronym>
+ handler:</para>
- <programlisting language="java">package sax.rdbms;
+ <programlisting language="java">package sax.rdbms;
...
public class HtmlEventHandler extends DefaultHandler{
public void startDocument() {
@@ -7861,10 +8025,11 @@ public class HtmlEventHandler extends DefaultHandler{
}
private DbAccess dbaccess = new DbAccess();
}</programlisting>
- </answer>
- </qandaentry>
- </qandadiv>
- </qandaset>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
</section>
<section xml:id="saxValidate">
diff --git a/ws/eclipse/Jdbc/src/main/java/sax/count/Driver.java b/ws/eclipse/Jdbc/src/main/java/sax/count/Driver.java
new file mode 100644
index 000000000..e09282ff6
--- /dev/null
+++ b/ws/eclipse/Jdbc/src/main/java/sax/count/Driver.java
@@ -0,0 +1,34 @@
+package sax.count;
+
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+import org.xml.sax.XMLReader;
+
+import sax.stat.v2.MyErrorHandler;
+
+/** Driver class */
+public class Driver {
+
+ /**
+ * @param argv
+ * unused
+ * @throws Exception
+ */
+ public static void main(String argv[]) throws Exception {
+
+ final SAXParserFactory saxPf = SAXParserFactory.newInstance();
+ final SAXParser saxParser = saxPf.newSAXParser();
+ final XMLReader xmlReader = saxParser.getXMLReader();
+ final ListTagNamesHandler handler = new ListTagNamesHandler();
+ xmlReader.setContentHandler(handler);
+ xmlReader.setErrorHandler(new MyErrorHandler());
+ xmlReader.parse("Input/Xml/Memo/message.xml");
+
+ System.out.print("List of elements: {");
+ for (String elementName : handler.getTagNames()) {
+ System.out.print(elementName + " ");
+ }
+ System.out.println("}");
+ }
+}
\ No newline at end of file
diff --git a/ws/eclipse/Jdbc/src/main/java/sax/count/ListTagNamesHandler.java b/ws/eclipse/Jdbc/src/main/java/sax/count/ListTagNamesHandler.java
new file mode 100644
index 000000000..cfb6bb92c
--- /dev/null
+++ b/ws/eclipse/Jdbc/src/main/java/sax/count/ListTagNamesHandler.java
@@ -0,0 +1,35 @@
+package sax.count;
+
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+import org.xml.sax.Attributes;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.DefaultHandler;
+
+/** Reading attributes from element events */
+public class ListTagNamesHandler extends DefaultHandler {
+
+ // A SortedSet by definition does not contain any duplicates.
+ private SortedSet<String> elementNames = new TreeSet<>();
+
+ @Override
+ public void startDocument() throws SAXException {
+ elementNames.clear(); // May contain elements from a previous run.
+ }
+
+ public void startElement(String namespaceUri, String localName,
+ String rawName, Attributes attrs) {
+ // In case the current element name has already been inserted
+ // this method call will be silently ignored.
+ elementNames.add(rawName);
+ }
+
+ /**
+ * @return A sorted list of element names of he currently processed XML
+ * document without duplicates.
+ */
+ public String[] getTagNames() {
+ return elementNames.toArray(new String[0]);
+ }
+}
\ No newline at end of file
--
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