Fix a bug in the factory finding algorithm for service files.

git-svn-id: https://svn.apache.org/repos/asf/xml/commons/trunk@226248 13f79535-47bb-0310-9956-ffa450edef68

java/external/src/javax/xml/xpath/XPathFactoryFinder.java

@@ -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 @@ import java.util.Properties;
 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 @@ class XPathFactoryFinder  {
             URL resource = (URL)sitr.next();
             debugPrintln("looking into " + resource);
             try {
-                //sf = loadFromProperty(uri,resource.toExternalForm(),resource.openStream());
+                sf = loadFromServicesFile(uri, resource.toExternalForm(), ss.getURLInputStream(resource));
-                sf = loadFromProperty(uri,resource.toExternalForm(),ss.getURLInputStream(resource));
                 if(sf!=null)    return sf;
             } catch(IOException e) {
                 if( debug ) {
@@ -271,28 +279,66 @@ class XPathFactoryFinder  {
         protected abstract Object value();
     }
     
-    /**
+    /** Searches for a XPathFactory for a given uri in a META-INF/services file. */
-     * Looks up a value in a property file
+    private XPathFactory loadFromServicesFile(String uri, String resourceName, InputStream in) {
-     * 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();
+        BufferedReader rd;
-        props.load(in);
+        try {
-        in.close();
+            rd = new BufferedReader(new InputStreamReader(in, "UTF-8"), DEFAULT_LINE_LENGTH);
-        String factoryClassName = props.getProperty(keyName);
+        } catch (java.io.UnsupportedEncodingException e) {
-        if(factoryClassName != null){
+            rd = new BufferedReader(new InputStreamReader(in), DEFAULT_LINE_LENGTH);
-            debugPrintln("found "+keyName+" = " + factoryClassName);
-            return createInstance(factoryClassName);
-        } else {
-            debugPrintln(keyName+" is not in the property file");
-            return null;
         }
+        
+        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;
     }
         
     /**