Java DOM processing XML Keeping Carriage Returns

[Dr. Laurence Leff]

I am writing a Java program to read in XML file, modify some elements
slightly, and then write it out. That XML file is prepared
in Docbook.

It works fine, except that it is disturbing the carriage returns in places
where they have meaning.

Attached are a sample input file, the sample output file, and a simplified
version of my Java program. My real file, examines certain element's attributes
and adds certain elements to the DOM data structure.

How, best to write such a program, without disturbing the carriage returns
between "<programlisting>" and "</programlisting>"

Here is the input file. I need to preserve the formatting of the material
between "<programlisting>" and "</programlisting>"

<test>
<programlisting>
a
b
c d e f
</programlisting>
</test>



Here is the output file -- observe how the "a b c d e f" are now on
one line.
<?xml version="1.0" encoding="UTF-8"?>
<test>
<programlisting> a b c d e f </programlisting>
</test>

Here is the Java program:

import java.text.*;
import java.io.*;

import javax.xml.parsers.*;
import org.apache.xml.serialize.*;
import org.w3c.dom.*;
import org.xml.sax.*;

public class Test {
static PrintWriter debug = null;
static Document document = null;
static String OutputFileName;

static Element CreateElement (String ElementName, String Contents){
Element ToReturn;
ToReturn = document.createElement(ElementName);
Text T = document.createTextNode(Contents);
ToReturn.appendChild(T);
return ToReturn;
}
static Element CreateElement (String ElementName, String Contents, String AttributeName, String AttributeValue){
Element ToReturn = CreateElement(ElementName,Contents);
ToReturn.setAttribute(AttributeName,AttributeValue);
return ToReturn;
}


public static void main (String[] args) throws FileNotFoundException {
try {
debug = new PrintWriter (new FileWriter("debug.out"));
}
catch (Exception d) {System.out.println("cannot open debug file");}
Text T;
int j;
DocumentBuilder parser = null;
// Here we read in the data from the XML file
DocumentBuilderFactory Factory = DocumentBuilderFactory.newInstance();
String xmlFile = args[0];
File file = new File (xmlFile);
try {
parser = Factory.newDocumentBuilder();
}
catch (ParserConfigurationException pce) {
System.out.println ("Parser Configuration Exception " + pce.getMessage());
System.exit(0);
}
try {
document = parser.parse(file);
}
catch (SAXException se) {
System.out.println ("SAX Exception on parsing document " + se.getMessage());
System.exit(0);
}
catch (IOException ioe) {
System.out.println ("IO Exception on parsing document " + ioe.getMessage());
System.exit(0);
}
FileWriter out = null;
XMLSerializer X = null;
Element root = null;
OutputFileName=args[0];
try {
out = new FileWriter(OutputFileName+".OUT"+".xml");
out.flush();
OutputFormat o = new OutputFormat(document);
o.setIndent(5);
o.setIndenting(true);
X = new XMLSerializer(o);
X.setOutputCharStream(out);
}
catch (IOException e0) {
System.out.println ("problem in setting up to save XML file" + e0.getMessage());
e0.printStackTrace();
}

// use the XML functions to dump the materials
try {
X.serialize(document);
out.flush();
} catch (IOException e2) {System.out.println("error writing file " + e2.getMessage());e2.printStackTrace();}

debug.close();

}
}

Dr. Laurence Leff Western Illinois University, Macomb IL 61455 ||(309) 298-1315
Stipes 447 Assoc. Prof. of Computer Sci. Pager: 309-367-0787 FAX: 309-298-2302
Secretary: eContracts Technical Committee OASIS Legal XML Member Section

 

[Stanimir Stamenkov]

/Dr. Laurence Leff/:

It works fine, except that it is disturbing the carriage returns in places
where they have meaning.

... XML processor MUST behave as if it normalized all line breaks in
external parsed entities (including the document entity) on input,
before parsing, by translating both the two-character sequence #xD
#xA and any #xD that is not followed by #xA to a single #xA
character.

So you have to include the carriage returns in the source XML data
using character references -

 

[Stanimir Stamenkov]

/Stanimir Stamenkov/:

So you have to include the carriage returns in the source XML data using
character references -

As far as I see:

Document doc;
... // initialize a new empty 'doc'
Element elem = doc.createElement("test");
elem.appendChild(doc.createTextNode(
"A line of text.\r\n\r\nAnother line."));
doc.appendChild(elem);
// serialize the 'doc'

Serialization using the standard JAXP Transformations API (using a
"copy transformer") correctly outputs
in place of the CR
characters so they would be the read next time again.

 

[Dr. Laurence Leff]

Dr. Stamenkov:

Thank you for your quick responses to my question on using Java
to process XML files that contain formatted text such as programs.

I tried your suggestion of using the entity reference for carriage
return,
, (I wrote a perl script to identify my
programlisting sections and make the replacement.)

It did not help.

Here is the sample input (after including the entity references)

<section><para>
abc
def
<programlisting>
ghi
jkl
mno
</programlisting>
ghi
jkl
</para></section>

Here is the output of the Java program. Observe that the carriage return
and formatting in the "programlisting" section are being changed.

<?xml version="1.0" encoding="UTF-8"?>
<section>
<para> abc def <programlisting> ghi jkl mno </programlisting>
ghi jkl </para>
</section>

This output was from the same Java program as before.

I also tried the startPreserving() option on the OutputSerializer
and removing the invocations of the methods setIndent and setIndenting.
I also tried removing the carraige returns between the line, replacing
them with the return,
These made no change.

I then tried the other suggestion:

import java.text.*;
import java.io.*;

import javax.xml.parsers.*;
import org.apache.xml.serialize.*;
import org.w3c.dom.*;
import org.xml.sax.*;

public class T{
static PrintWriter debug = null;
static String OutputFileName;



public static void main (String[] args) throws ParserConfigurationException,FileNotFoundException {
try {
debug = new PrintWriter (new FileWriter("debug.out"));
}
catch (Exception d) {System.out.println("cannot open debug file");}
Text T;
int j;
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
Document doc;
DocumentBuilder db = dbf.newDocumentBuilder();
doc = db.newDocument();
Element elem = doc.createElement("test");
elem.appendChild(doc.createTextNode(
"A line of text \r\n\r\nAnother line"));

doc.appendChild(elem);

FileWriter out = null;
XMLSerializer X = null;
Element root = null;
try {
out = new FileWriter(OutputFileName+".OUT"+".xml");
out.flush();
OutputFormat o = new OutputFormat(doc);
//o.setIndent(5);
//o.setIndenting(true);
X = new XMLSerializer(o);
X.setOutputCharStream(out);
}
catch (IOException e0) {
System.out.println ("problem in setting up to save XML file" + e0.getMessage());
e0.printStackTrace();
}

// use the XML functions to dump the materials
try {
X.serialize(doc);
out.flush();
} catch (IOException e2) {System.out.println("error writing file " + e2.getMessage());e2.printStackTrace();}

debug.close();

}
}

I got this output:

<?xml version="1.0" encoding="UTF-8"?>
<test>A line of text Another line</test>

Perhaps, there is a version or configuration problem with my parser software.
I am using Xerces-2_4_0.

Thank you for any further assistance that you or anyone else
reading this newsgroup can provide.

Dr. Laurence Leff Western Illinois University, Macomb IL 61455 ||(309) 298-1315
Stipes 447 Assoc. Prof. of Computer Sci. Pager: 309-367-0787 FAX: 309-298-2302
Secretary: eContracts Technical Committee OASIS Legal XML Member Section

 

[Stanimir Stamenkov]

/Dr. Laurence Leff/:

I tried your suggestion of using the entity reference for carriage
return,
...

It did not help.

Here is the sample input (after including the entity references)

<section><para>
abc
def
<programlisting>
ghi
jkl
mno
</programlisting>
ghi
jkl
</para></section>
[...]

Perhaps, there is a version or configuration problem with my parser software.
I am using Xerces-2_4_0.

As I've mentioned in my previous reply I've used the JAXP
Transformations API (part of the standard Java 1.4 framework) to
serialize the data. I have Xerces2 version 2.6.2 but I haven't used
its 'serialize' package. It could be these 'Serializer' classes need
additional configuration or just they don't behave well in the
version you have. The Xerces version I have provides implementation
of the DOM Level 3 Load and Save API (which is now part of the
standard Java 5 framework) but I haven't tried that, too.

I've prepared an example for you to try:

http://www.geocities.com/stanio/test/XMLInputOutputTest.java
http://www.geocities.com/stanio/test/input.xml

It reads the "input.xml" file (which is copy of the sample input
you've given above), dumps its contents to the console where CR and
LF characters are indicated/replaced with "[CR]" and "[LF]" strings
(all on one line). Then it saves the read DOM data to "output.xml".

In addtion a "test.xml" file is created with DOM data constructed
using the 'Document' factory methods (as in my previous example).