Developing an Eclipse BIRT XML Report Rendering Extension, Page 5

Understanding LoadExportSchema

The org.eclipse.birt.report.engine.emitter.xml.LoadExportSchema class optionally loads an XML Schema by performing the following operations:

• Specifies the default substitution patterns for the XML tags
• Calls the readSchemaFile( ) method
• Specifies an accessor method for each tag that returns a value to XMLReportEmitter for output to the export file

Listing 8 shows the specification of the default substitution patterns for the XML tags and the constructor, which calls the readSchemaFile( ) method.

Listing 8: The LoadExportSchema class

package org.eclipse.birt.report.engine.emitter.xml;
...
public class LoadExportSchema{

   protected String fileName = "";

   protected String startTag = "<?xml version=\"1.0\"
                    encoding=\"UTF-8\"?>";
   protected String textTag = "<text>??value</text>";
   protected String imageTag = "<image>??value</image>";
   protected String dataTag = "<data>??value</data>";
   protected String labelTag = "<label>??value</label>";
   protected String endTag = "</report>";
   protected String reportTag = "<report:??name>";

   public LoadExportSchema(String fileName)
   {
      if ( fileName.length() > 0 )
      {
         this.fileName = fileName;
         readSchemaFile();
      }
   }

The readSchemaFile( ) method reads the XML Schema file, one line at a time, replacing the default values for the patterns of the XML version, text, image, data, label, and report tags with the values specified in the XML Schema file.

Listing 9 shows the code for the readSchemaFile( ) method.

Listing 9: The readSchemaFile( ) method

private void readSchemaFile()
{
   BufferedReader input = null;
   try
   {
      input = new BufferedReader(
         new FileReader(fileName) );
      String line = null; //not declared within while loop
      while (( line = input.readLine()) != null){
         int pos = line.indexOf("=");
         if ( pos > 0 )
         {
            String index = line.substring(0, pos );
            String indexTag = line.substring(pos + 1,
               line.length());
            if ( index.equalsIgnoreCase(
               XMLTags.labelControl ) )
            {
               labelTag = indexTag;
         }
         if ( index.equalsIgnoreCase( XMLTags.imageControl ) )
         {
            imageTag = indexTag;
         }
         if ( index.equalsIgnoreCase( XMLTags.dataControl ) )
         {
            dataTag = indexTag;
         }
         if ( index.equalsIgnoreCase( XMLTags.startControl ) )
         {
            startTag = indexTag;
         }
         if ( index.equalsIgnoreCase( XMLTags.endControl ) )
         {
            endTag = indexTag;
         }
         if ( index.equalsIgnoreCase( XMLTags.reportControl ) )
         {
            reportTag = indexTag;
         }
      }
      catch (FileNotFoundException ex)
      {
         ex.printStackTrace( );
      }
      catch (IOException ex)
      {
         ex.printStackTrace( );
      }
      finally
      {
         try
         {
            if (input!= null)
            {
               input.close( );
            }
         }
         catch (IOException ex)
         {
            ex.printStackTrace( );
         }
      }
}