Dynamically determine correct app XSL file to include; default to an empty template file; default to a string if all else fails.

Author	Dave Jarvis <email>
Date	2015-01-15 01:44:20 GMT-0800
Commit	b6aec12ae4fd0fc3c6c23a52eb22ed2382a1cce4
Parent	6aac04e

source/java/to/discuss/App.java

		import javax.xml.transform.TransformerFactory;
		import javax.xml.transform.Transformer;
		+import javax.xml.transform.URIResolver;
		+
		+import to.discuss.util.AppURIResolver;

		/**


		protected void applyParameters( Transformer t ) {
		- t.setParameter( "app", getClass().getSimpleName().toLowerCase() );
		+ t.setParameter( "app", getAppName() );
		}



		private String getDocumentFilename() {
		- return String.format(
		- "database/%s.xml", getClass().getSimpleName().toLowerCase() );
		+ return String.format( "database/%s.xml", getAppName() );
		}



		protected TransformerFactory getTransformerFactory() {
		- return TransformerFactory.newInstance();
		+ TransformerFactory tf = TransformerFactory.newInstance();
		+ URIResolver resolver = tf.getURIResolver();
		+ tf.setURIResolver( new AppURIResolver( this, resolver ) );
		+
		+ return tf;
		}

		protected Transformer getTransformer() throws Exception {
		return getTransformerFactory().newTransformer( getStylesheet() );
		+ }
		+
		+ /**
		+ * Returns the app name, in lowercase.
		+ */
		+ public String getAppName() {
		+ return getClass().getSimpleName().toLowerCase();
		}
		}

source/java/to/discuss/Base.java

		package to.discuss;

		+import java.io.FileNotFoundException;
		import java.io.InputStream;
		+import java.io.IOException;

		/**

		* @throws Exception Any error opening the file.
		*/
		- public default InputStream open( String filename ) throws Exception {
		+ public default InputStream open( String filename ) throws IOException {
		ClassLoader loader = Thread.currentThread().getContextClassLoader();
		- return loader.getResourceAsStream( filename );
		+ InputStream result = loader.getResourceAsStream( filename );
		+
		+ if( result == null ) {
		+ throw new FileNotFoundException( filename );
		+ }
		+
		+ return result;
		}
		}

source/java/to/discuss/util/AppURIResolver.java


		+/**
		+ * MIT License
		+ *
		+ * Copyright 2015 White Magic Software, Ltd.
		+ */
		+package to.discuss.util;
		+
		+import java.io.IOException;
		+import java.io.Reader;
		+import java.io.StringReader;
		+
		+import java.net.URI;
		+
		+import javax.xml.transform.Source;
		+import javax.xml.transform.TransformerException;
		+import javax.xml.transform.URIResolver;
		+import javax.xml.transform.stream.StreamSource;
		+
		+import to.discuss.App;
		+import to.discuss.Base;
		+
		+/**
		+ * Extends java.util.Properties to recursively parse ${property} values. This
		+ */
		+public class AppURIResolver implements URIResolver, Base {
		+ private URIResolver delegate;
		+ private App app;
		+
		+ public AppURIResolver( App app, URIResolver delegate ) {
		+ setApp( app );
		+ setDelegate( delegate );
		+ }
		+
		+ /**
		+ * Dynamically resolve the path to the include file based on the app name.
		+ */
		+ @Override
		+ public Source resolve( String href, String base )
		+ throws TransformerException {
		+ Source result = null;
		+ URI uri = null;
		+
		+ try {
		+ uri = new URI( href );
		+ }
		+ catch( Exception e ) {
		+ throw new TransformerException( e );
		+ }
		+
		+ // The XSLT file has a URI path that allows for a file to be included
		+ // dynamically.
		+ if( "import".equalsIgnoreCase( uri.getScheme() ) &&
		+ "discuss.to".equalsIgnoreCase( uri.getAuthority() ) ) {
		+ result = openAppTemplate();
		+ }
		+ else {
		+ result = getDelegate().resolve( href, base );
		+ }
		+
		+ return result;
		+ }
		+
		+ /**
		+ * Guaranteed to open an XSL template that corresponds to the app name.
		+ * If no template is found, or the default template file is missing, this
		+ * will return a hard-coded string as a StreamSource.
		+ *
		+ * @return A valid StreamSource containing a stylesheet DOM.
		+ */
		+ private Source openAppTemplate() {
		+ Source result = null;
		+
		+ try {
		+ result = new StreamSource( open( getStylesheetFilename() ) );
		+ }
		+ catch( IOException ioe ) {
		+ try {
		+ result = new StreamSource( open( "xsl/template.xsl" ) );
		+ }
		+ catch( Exception e ) {
		+ result = new StreamSource( getDefaultTemplate() );
		+ }
		+ }
		+
		+ return result;
		+ }
		+
		+ /**
		+ * If the file-based template cannot be found, then use a hard-coded,
		+ * fail-safe version.
		+ */
		+ private Reader getDefaultTemplate() {
		+ return new StringReader(
		+ "<?xml version='1.0' encoding='utf-8'?>" +
		+ "<xsl:stylesheet version='2.0' " +
		+ "xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>" +
		+ "</xsl:stylesheet>" );
		+ }
		+
		+ private String getStylesheetFilename() {
		+ return String.format( "xsl/%s.xsl", getApp().getAppName() );
		+ }
		+
		+ private void setApp( App app ) {
		+ this.app = app;
		+ }
		+
		+ private App getApp() {
		+ return this.app;
		+ }
		+
		+ private void setDelegate( URIResolver delegate ) {
		+ this.delegate = delegate;
		+ }
		+
		+ private URIResolver getDelegate() {
		+ return this.delegate;
		+ }
		+}
		+
		+

source/xsl/common.xsl

		encoding="utf-8"/>

		-<!-- For including CSS and JavaScript references. -->
		+<!-- Custom URI resolver to import an XSL file corresponding to the app. -->
		+<xsl:include href="import://discuss.to/app"/>
		+
		+<!-- Include CSS and JavaScript files corresponding to the app. -->
		<xsl:param name="app" />

source/xsl/template.xsl

		+<?xml version='1.0' encoding='utf-8'?>
		+<xsl:stylesheet version='2.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>
		+</xsl:stylesheet>

Delta	155 lines added, 7 lines removed, 148-line increase