package org.g4studio.core.mvc.xstruts.chain.commands;
import org.apache.commons.chain.Catalog;
import org.apache.commons.chain.CatalogFactory;
import org.apache.commons.chain.Command;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.g4studio.core.mvc.xstruts.chain.contexts.ActionContext;
import org.g4studio.core.mvc.xstruts.config.ActionConfig;
/**
* <p>
* Invoke the appropriate <code>Command</code> for this request. If the
* context's <code>ActionConfig</code> has no <code>command</code> property
* defined, no action will be taken. If the specified command cannot be found, a
* warning will be logged, but processing will continue. Depending on how the
* chain is configured, this can be used in place of an <code>Action</code> or
* as a method of performing pre-processing.
* </p>
*
* <p>
* If used instead of an action, the command which is looked up should put an
* ActionForward into the context, unless it has already dealt with the
* response.
* </p>
*
* @version $Id: ExecuteCommand.java 421119 2006-07-12 04:49:11Z wsmoak $
*/
public class ExecuteCommand extends ActionCommandBase {
// ------------------------------------------------------ Instance Variables
/**
* Provide Commons Logging instance for this class.
*/
private static final Log LOG = LogFactory.getLog(ExecuteCommand.class);
// ---------------------------------------------------------- Public Methods
/**
* <p>
* If the <code>context</code> is "valid", lookup a command and execute it.
* </p>
*
* @param actionCtx
* The <code>Context</code> for the current request
* @return the result of the lookup command's <code>execute</code> method,
* if executed, or <code>false</code> if it was not executed.
* @throws Exception
* on any error
*/
public boolean execute(ActionContext actionCtx) throws Exception {
if (shouldProcess(actionCtx)) {
Command command = getCommand(actionCtx);
if (command != null) {
return (command.execute(actionCtx));
}
}
return (false);
}
/**
* <p>
* Evaluate the current context to see if a command should even be executed.
* </p>
*
* @param context
* A valid ActionContext
* @return TRUE if the pending Command should be executed
*/
protected boolean shouldProcess(ActionContext context) {
// Skip processing if the current request is not valid
Boolean valid = context.getFormValid();
return ((valid != null) && valid.booleanValue());
}
/**
* <p>
* Find the <code>ActionConfig</code> in the current context and, if it is
* properly configured, lookup the appropriate <code>commons-chain</code>
* command.
* </p>
*
* @param context
* A valid ActionContext
* @return a <code>Command</code> to execute, or null if none is specified
* or if the specified command cannot be found.
*/
protected Command getCommand(ActionContext context) {
ActionConfig actionConfig = context.getActionConfig();
String commandName = actionConfig.getCommand();
if (commandName == null) {
return null;
}
String catalogName = actionConfig.getCatalog();
return getCommand(commandName, catalogName);
}
/**
* <p>
* Retrieve the specified Command from the specified Catalog.
* </p>
*
* @param commandName
* The Command to retrieve.
* @param catalogName
* The Catalog to search.
* @return Instantiated Command, or null
*/
protected Command getCommand(String commandName, String catalogName) {
if (commandName == null) {
return null;
}
Catalog catalog;
if (catalogName != null) {
catalog = CatalogFactory.getInstance().getCatalog(catalogName);
if (catalog == null) {
LOG.warn("When looking up " + commandName + "," + " no catalog found under " + catalogName);
return null;
}
} else {
catalogName = "the default catalog";
catalog = CatalogFactory.getInstance().getCatalog();
if (catalog == null) {
LOG.warn("When looking up " + commandName + "," + " no default catalog found.");
return null;
}
}
if (LOG.isDebugEnabled()) {
LOG.debug("looking up command " + commandName + " in " + catalogName);
}
return catalog.getCommand(commandName);
}
}