reloadingjavaactionfactory.java

webwork source

package webwork.action.factory;

import java.net.URL;
import java.net.MalformedURLException;
import java.util.StringTokenizer;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import webwork.util.classloader.WebworkClassLoader;
import webwork.util.ClassLoaderUtils;
import webwork.action.Action;
import webwork.config.Configuration;

public class ReloadingJavaActionFactory extends JavaActionFactory
{
  private static final Log log = LogFactory.getLog(ReloadingJavaActionFactory.class);
  //we store this here as well as the parent field to avoid having to cast to call methods on the classloader
  private WebworkClassLoader reloadingClassLoader;
  private URL source;

  public ReloadingJavaActionFactory()
  {
    URL url = getClass().getResource("/webwork.properties");
    System.out.println(this + " " + url);
    if (url == null)
    {
      log.warn("Cannot find CodeSource for webwork, unable to creare reloading action factory");
    }
    else
    {
      try
      {
        String urlVal = url.toString();
        source = new URL(urlVal.substring(0, urlVal.lastIndexOf("webwork.properties")));
        log.debug("Creating classloader for url "  + source);
        WebworkClassLoader actionLoader = WebworkClassLoader.getInstance(source, Thread.currentThread().getContextClassLoader());
        StringTokenizer tok = new StringTokenizer(Configuration.getString("webwork.action.packages").trim(), ", ");
        String[] packages = new String[tok.countTokens()];
        int counter = 0;
        while(tok.hasMoreTokens())
        {
          packages[counter++] = tok.nextToken();
        }
        actionLoader.setPackages(packages);
        this.actionLoader = actionLoader;
        this.reloadingClassLoader = actionLoader;
      }
      catch(MalformedURLException ex)
      {
        log.error("Grr", ex);
      }
    }
  }

  /**
   * Returns a loaded and instantiated action class instance using a fully
   * qualified classname.
   *
   * @param name classname of the action to be created
   * @return the action corresponding to the given Java class name
   */
  public Action getActionImpl(String name) throws Exception
  {
    if(reloadingClassLoader!=null && reloadingClassLoader.isStale())
    {
      synchronized(this)
      {
        log.debug("Classes modified, reloading...");
        reloadingClassLoader = (WebworkClassLoader)reloadingClassLoader.clone();
        actionLoader = reloadingClassLoader;
      }
    }
    Class actionClass = null;
    try
    {
      actionClass = reloadingClassLoader.loadClass(name);
    }
    catch (Exception e)
    {
      try
      {
        actionClass = ClassLoaderUtils.loadClass(name, getClass());
      }
      catch (Exception e2)
      {
        // Not found
        throw new IllegalArgumentException("Action '" + name + "' not found");
      }
    }
    try
    {
      Action action = (Action)actionClass.newInstance();
      return action;
    }
    catch (Exception e)
    {
      throw new IllegalArgumentException("Action '" + name + "' could not be instantiated:" + e);
    }
  }
}