cvs commit: xml-commons/java/external/src/javax/xml/xpath XPathFactoryFinder.java

[mk...@apache.org]

mkwan       2005/06/21 08:08:51

  Modified:    java/external/src/javax/xml/xpath XPathFactoryFinder.java
  Log:
  Fix a bug in the factory finding algorithm for service files.
  
  Revision  Changes    Path
  1.2       +72 -26    xml-commons/java/external/src/javax/xml/xpath/XPathFactoryFinder.java
  
  Index: XPathFactoryFinder.java
  ===================================================================
  RCS file: /home/cvs/xml-commons/java/external/src/javax/xml/xpath/XPathFactoryFinder.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -r1.1 -r1.2
  --- XPathFactoryFinder.java	8 Apr 2005 10:39:14 -0000	1.1
  +++ XPathFactoryFinder.java	21 Jun 2005 15:08:51 -0000	1.2
  @@ -17,10 +17,12 @@
   
   package javax.xml.xpath;
   
  +import java.io.BufferedReader;
   import java.io.File;
   import java.io.FileInputStream;
   import java.io.IOException;
   import java.io.InputStream;
  +import java.io.InputStreamReader;
   import java.net.URL;
   import java.util.ArrayList;
   import java.util.Enumeration;
  @@ -38,8 +40,15 @@
   class XPathFactoryFinder  {
   
       private static SecuritySupport ss = new SecuritySupport() ;
  +    
       /** debug support code. */
       private static boolean debug = false;
  +    
  +    /**
  +     * Default columns per line.
  +     */
  +    private static final int DEFAULT_LINE_LENGTH = 80;
  +    
       static {
           // Use try/catch block to support applets
           try {
  @@ -204,8 +213,7 @@
               URL resource = (URL)sitr.next();
               debugPrintln("looking into " + resource);
               try {
  -                //sf = loadFromProperty(uri,resource.toExternalForm(),resource.openStream());
  -                sf = loadFromProperty(uri,resource.toExternalForm(),ss.getURLInputStream(resource));
  +                sf = loadFromServicesFile(uri, resource.toExternalForm(), ss.getURLInputStream(resource));
                   if(sf!=null)    return sf;
               } catch(IOException e) {
                   if( debug ) {
  @@ -271,30 +279,68 @@
           protected abstract Object value();
       }
       
  -    /**
  -     * Looks up a value in a property file
  -     * while producing all sorts of debug messages.
  -     * 
  -     * @return null
  -     *      if there was an error.
  -     */
  -    private XPathFactory loadFromProperty( String keyName, String resourceName, InputStream in )
  -        throws IOException {
  -        debugPrintln("Reading "+resourceName );
  -        
  -        Properties props = new Properties();
  -        props.load(in);
  -        in.close();
  -        String factoryClassName = props.getProperty(keyName);
  -        if(factoryClassName != null){
  -            debugPrintln("found "+keyName+" = " + factoryClassName);
  -            return createInstance(factoryClassName);
  -        } else {
  -            debugPrintln(keyName+" is not in the property file");
  -            return null;
  +    /** Searches for a XPathFactory for a given uri in a META-INF/services file. */
  +    private XPathFactory loadFromServicesFile(String uri, String resourceName, InputStream in) {
  +
  +        debugPrintln("Reading " + resourceName );
  +        
  +        BufferedReader rd;
  +        try {
  +            rd = new BufferedReader(new InputStreamReader(in, "UTF-8"), DEFAULT_LINE_LENGTH);
  +        } catch (java.io.UnsupportedEncodingException e) {
  +            rd = new BufferedReader(new InputStreamReader(in), DEFAULT_LINE_LENGTH);
  +        }
  +        
  +        String factoryClassName = null;
  +        XPathFactory resultFactory = null;
  +        // See spec for provider-configuration files: http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html#Provider%20Configuration%20File
  +        while (true) {
  +            try {
  +                factoryClassName = rd.readLine();   
  +            } catch (IOException x) {
  +                // No provider found
  +                break;
  +            }
  +            if (factoryClassName != null) {
  +                // Ignore comments in the provider-configuration file
  +                int hashIndex = factoryClassName.indexOf('#');
  +                if (hashIndex != -1) {
  +                    factoryClassName = factoryClassName.substring(0, hashIndex);
  +                }
  +                
  +                // Ignore leading and trailing whitespace
  +                factoryClassName = factoryClassName.trim();
  +                
  +                // If there's no text left or if this was a blank line, go to the next one.
  +                if (factoryClassName.length() == 0) {
  +                    continue;
  +                }
  +                
  +                try {
  +                    // Found the right XPathFactory if its isObjectModelSupported(String uri) method returns true.
  +                    XPathFactory foundFactory = (XPathFactory) createInstance(factoryClassName);
  +                    if (foundFactory.isObjectModelSupported(uri)) {
  +                        resultFactory = foundFactory;
  +                        break;
  +                    }
  +                }
  +                catch (Exception e) {}
  +            }
  +            else {
  +                break;
  +            }
  +        }
  +        
  +        try {
  +            // try to close the reader.
  +            rd.close();
           }
  +        // Ignore the exception.
  +        catch (IOException exc) {}
  +        
  +        return resultFactory;
       }
  -    
  +        
       /**
        * Returns an {@link Iterator} that enumerates all 
        * the META-INF/services files that we care.