initial commit for a new layout.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@969 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/PluginManager.java

@@ -0,0 +1,146 @@
+package hudson;
+
+import hudson.model.Hudson;
+import hudson.util.Service;
+import java.util.logging.Level;
+
+import javax.servlet.ServletContext;
+import java.io.File;
+import java.io.FilenameFilter;
+import java.io.IOException;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.logging.Logger;
+
+/**
+ * Manages {@link PluginWrapper}s.
+ *
+ * @author Kohsuke Kawaguchi
+ */
+public final class PluginManager {
+    /**
+     * All discovered plugins.
+     */
+    private final List<PluginWrapper> plugins = new ArrayList<PluginWrapper>();
+
+    /**
+     * All active plugins.
+     */
+    private final List<PluginWrapper> activePlugins = new ArrayList<PluginWrapper>();
+
+    /**
+     * Plug-in root directory.
+     */
+    public final File rootDir;
+
+    public final ServletContext context;
+
+    /**
+     * {@link ClassLoader} that can load all the publicly visible classes from plugins
+     * (and including the classloader that loads Hudson itself.)
+     *
+     */
+    // implementation is minmal --- just enough to run XStream
+    // and load plugin-contributed classes.
+    public final ClassLoader uberClassLoader = new UberClassLoader();
+
+    public PluginManager(ServletContext context) {
+        this.context = context;
+        rootDir = new File(Hudson.getInstance().getRootDir(),"plugins");
+        if(!rootDir.exists())
+            rootDir.mkdirs();
+
+        File[] archives = rootDir.listFiles(new FilenameFilter() {
+            public boolean accept(File dir, String name) {
+                return name.endsWith(".hpi")        // plugin jar file
+                    || name.endsWith(".hpl");       // linked plugin. for debugging.
+            }
+        });
+
+        if(archives==null) {
+            LOGGER.severe("Hudson is unable to create "+rootDir+"\nPerhaps its security privilege is insufficient");
+            return;
+        }
+        for( File arc : archives ) {
+            try {
+                PluginWrapper p = new PluginWrapper(this, arc);
+                plugins.add(p);
+                if(p.isActive())
+                    activePlugins.add(p);
+            } catch (IOException e) {
+                LOGGER.log(Level.SEVERE, "Failed to load a plug-in " + arc, e);
+            }
+        }
+    }
+
+    public List<PluginWrapper> getPlugins() {
+        return plugins;
+    }
+
+    public PluginWrapper getPlugin(String shortName) {
+        for (PluginWrapper p : plugins) {
+            if(p.getShortName().equals(shortName))
+                return p;
+        }
+        return null;
+    }
+
+    /**
+     * Discover all the service provider implementations of the given class,
+     * via <tt>META-INF/services</tt>.
+     */
+    public <T> Collection<Class<? extends T>> discover( Class<T> spi ) {
+        Set<Class<? extends T>> result = new HashSet<Class<? extends T>>();
+
+        for (PluginWrapper p : activePlugins) {
+            Service.load(spi, p.classLoader, result);
+        }
+
+        return result;
+    }
+
+    /**
+     * Orderly terminates all the plugins.
+     */
+    public void stop() {
+        for (PluginWrapper p : activePlugins) {
+            p.stop();
+        }
+    }
+
+    private final class UberClassLoader extends ClassLoader {
+        public UberClassLoader() {
+            super(PluginManager.class.getClassLoader());
+        }
+
+        @Override
+        protected Class<?> findClass(String name) throws ClassNotFoundException {
+            for (PluginWrapper p : activePlugins) {
+                try {
+                    return p.classLoader.loadClass(name);
+                } catch (ClassNotFoundException e) {
+                    //not found. try next
+                }
+            }
+            // not found in any of the classloader. delegate.
+            throw new ClassNotFoundException(name);
+        }
+
+        @Override
+        protected URL findResource(String name) {
+            for (PluginWrapper p : activePlugins) {
+                URL url = p.classLoader.getResource(name);
+                if(url!=null)
+                    return url;
+            }
+            return null;
+        }
+    }
+
+    private static final Logger LOGGER = Logger.getLogger(PluginManager.class.getName());
+
+}