Changeset 26494 for main/trunk/greenstone3

Timestamp:

2012-11-21T16:13:59+13:00 (11 years ago)

Author:

ak19

Message:

1. Adding new Library class TransformingLibrary.java that takes a GS3 o=xml input file and an XSLT file (like o=skinandlibdoc) and applies the XSLT to the XML to produce the final GS3 html page. 2. Needed a custom transform() method in XMLTransformer to get this to work as the XML and XSLT files can be located anywhere, but the XSLT import statements that the input XSLT file makes should be resolved to absolute paths despite specifying only relative paths. 3. Updated Library2.java to ensure GSDL3SRCHOME is set before it is run, in order to set GSDL3HOME correctly.

Location:

main/trunk/greenstone3/src/java/org/greenstone/gsdl3

Files:

• Library2.java (modified) (1 diff)
• TransformingLibrary.java (added)
• util/XMLTransformer.java (modified) (3 diffs)

main/trunk/greenstone3/src/java/org/greenstone/gsdl3/Library2.java

@@ -95 +95 @@
     {
 
+        if (System.getenv("GSDL3SRCHOME") == null) {
+        System.out.println("Before calling this script, run: source gs3-setup.sh"); 
+        System.exit(1);
+        }
+
         if (args.length != 2)
         {

main/trunk/greenstone3/src/java/org/greenstone/gsdl3/util/XMLTransformer.java

@@ -25 +25 @@
 import java.io.FileWriter;
 import java.io.InputStreamReader;
+import java.io.IOException;
 import java.io.StringReader;
 import java.io.StringWriter;
 import java.io.UnsupportedEncodingException;
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URI;
+import java.net.URL;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -40 +45 @@
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.URIResolver;
 import javax.xml.transform.dom.DOMResult;
 import javax.xml.transform.dom.DOMSource;
@@ -264 +270 @@
         }
     }
+
+    /**
+      When transforming an XML with an XSLT from the command-line, there's two problems if calling 
+      XMLTransformer.transform(File xslt, File xml):
+
+      1. Need to run the transformation process from the location of the stylesheet, else it can't find
+      the stylesheet in order to load it. This is resolved by setting the SystemID for the stylesheet.
+
+      2. The XSLT stylesheet has <xsl:import> statements importing further XSLTs which are furthermore 
+      specified by relative paths, requiring that the XSLT (and perhaps also XML) input file is located
+      in the folder from which the relative paths of the import statements are specified. This is resolved
+      by working out the absolute path of each imported XSLT file and setting their SystemIDs too.
+
+      Without solving these problems, things will only work if we 1. run the transformation from the 
+      web/interfaces/default/transform folder and 2. need to have the input XSLT file (and XML?)
+      placed in the web/interfacces/default/transform folder too
+
+      Both parts of the solution are described in:
+      http://stackoverflow.com/questions/3699860/resolving-relative-paths-when-loading-xslt-filse
+
+      After the systemID on the XSLT input file is set, we can run the command from the toplevel GS3 
+      folder.
+      After resolving the URIs of the XSLT files imported by the input XSLT, by setting their systemIDs,
+      the input XSLT (and XML) file need not be located in web/interfaces/default/transform anymore.
+     */
+    public Node transform(File stylesheet, File source, String interfaceName, Document docDocType)
+    {
+        try
+        {
+            TransformErrorListener transformerErrorListener = (TransformErrorListener) this.t_factory.getErrorListener();
+            transformerErrorListener.setStylesheet(stylesheet);
+
+            // http://stackoverflow.com/questions/3699860/resolving-relative-paths-when-loading-xslt-files
+            Source xsltSource = new StreamSource(new InputStreamReader(new FileInputStream(stylesheet), "UTF-8"));
+            URI systemID = stylesheet.toURI();
+            try {               
+                URL url = systemID.toURL();         
+                xsltSource.setSystemId(url.toExternalForm());
+            } catch (MalformedURLException mue) {
+                logger.error("Warning: Unable to set systemID for stylesheet to " + systemID);
+                logger.error("Got exception: " + mue.getMessage(), mue);
+            }
+
+            this.t_factory.setURIResolver(new ClasspathResourceURIResolver(interfaceName));         
+            Transformer transformer = this.t_factory.newTransformer(xsltSource);
+            // Alternative way of instantiating a newTransformer():
+            //Templates cachedXSLT = this.t_factory.newTemplates(xsltSource);
+            //Transformer transformer = cachedXSLT.newTransformer();
+
+            DOMResult result = (docDocType == null) ? new DOMResult() : new DOMResult(docDocType);
+            StreamSource streamSource = new StreamSource(new InputStreamReader(new FileInputStream(source), "UTF-8"));
+
+            transformer.setErrorListener(new TransformErrorListener(stylesheet, streamSource));
+
+            transformer.transform(streamSource, result);
+            return result.getNode().getFirstChild();
+        }
+        catch (TransformerConfigurationException e)
+        {
+            return transformError("XMLTransformer.transform(File, File)" + "\ncouldn't create transformer object for files\n" + stylesheet + "\n" + source, e);
+        }
+        catch (TransformerException e)
+        {
+            return transformError("XMLTransformer.transform(File, File)" + "\ncouldn't transform the source for files\n" + stylesheet + "\n" + source, e);
+        }
+        catch (UnsupportedEncodingException e)
+        {
+            return transformError("XMLTransformer.transform(File, File)" + "\ncouldn't read file due to an unsupported encoding\n" + stylesheet + "\n" + source, e);
+        }
+        catch (FileNotFoundException e)
+        {
+            return transformError("XMLTransformer.transform(File, File)" + "\ncouldn't find the file specified\n" + stylesheet + "\n" + source, e);
+        }
+    }
+
+    /** 
+     * Class for resolving the relative paths used for <xsl:import>s 
+     * when transforming XML with an XSLT
+    */
+    class ClasspathResourceURIResolver implements URIResolver {
+    String interface_name;
+
+    public ClasspathResourceURIResolver(String interfaceName) {
+        interface_name = interfaceName;     
+    }
+
+    /** 
+     * Override the URIResolver.resolve() method to turn relative paths of imported xslt files into
+     * absolute paths and set these absolute paths as their SystemIDs when loading them into memory.
+     * @see http://stackoverflow.com/questions/3699860/resolving-relative-paths-when-loading-xslt-files
+     */
+    
+    @Override
+        public Source resolve(String href, String base) throws TransformerException {
+        
+        //System.err.println("href: " + href); // e.g. href: layouts/main.xsl
+        //System.err.println("base: " + base); // e.g for *toplevel* base: file:/path/to/gs3-svn/CL1.xslt
+
+
+        // 1. for any xsl imported by the original stylesheet, try to work out its absolute path location
+        // by concatenating the parent folder of the base stylesheet file with the href of the file it
+        // imports (which is a path relative to the base file). This need not hold true for the very 1st
+        // base stylesheet: it may be located somewhere entirely different from the greenstone XSLT
+        // files it refers to. This is the case when running transforms on the commandline for testing
+
+        File importXSLfile = new File(href); // assume the xsl imported has an absolute path
+
+        if(!importXSLfile.isAbsolute()) { // imported xsl specifies a path relative to parent of base
+        try {
+            URI baseURI = new URI(base);
+            importXSLfile = new File(new File(baseURI).getParent(), href);
+
+            if(!importXSLfile.exists()) { // if the imported file does not exist, it's not
+            // relative to the base (the stylesheet file importing it). So look in the
+            // interface's transform subfolder for the xsl file to be imported
+            importXSLfile = new File(GSFile.interfaceStylesheetFile(GlobalProperties.getGSDL3Home(), interface_name, href));
+            }
+        } catch(URISyntaxException use) {
+            importXSLfile = new File(href); // try
+        }
+        }
+        
+        String importXSLfilepath = ""; // for printing the expected file path on error
+        try {
+        // path of import XSL file after resolving any .. and . dir paths
+        importXSLfilepath = importXSLfile.getCanonicalPath();
+        } catch(IOException ioe) { // resort to using the absolute path
+        importXSLfilepath = importXSLfile.getAbsolutePath();
+        }
+
+        // 2. now we know where the XSL file being imported lives, so set the systemID to its
+        // absolute path when loading it into a Source object
+        URI systemID = importXSLfile.toURI();
+        Source importXSLsrc = null;
+        try {
+        importXSLsrc = new StreamSource(new InputStreamReader(new FileInputStream(importXSLfile), "UTF-8"));        
+        URL url = systemID.toURL();         
+        importXSLsrc.setSystemId(url.toExternalForm());
+        } catch (MalformedURLException mue) {
+        logger.error("Warning: Unable to set systemID for imported stylesheet to " + systemID);
+        logger.error("Got exception: " + mue.getMessage(), mue);
+        } catch(FileNotFoundException fne) {
+        logger.error("ERROR: importXSLsrc file does not exist " + importXSLfilepath);
+        logger.error("\tError msg: " + fne.getMessage(), fne);
+        } catch(UnsupportedEncodingException uee) {
+        logger.error("ERROR: could not resolve relative path of import XSL file " + importXSLfilepath
+                 + " because of encoding issues: " + uee.getMessage(), uee);
+        }       
+        return importXSLsrc;
+        //return new StreamSource(this.getClass().getClassLoader().getResourceAsStream(href)); // won't work
+    }   
+    }
 
     public Node transform(File stylesheet, File source)