actiontag.java

webwork source

/*
 * WebWork, Web Application Framework
 *
 * Distributable under Apache license.
 * See terms of license at opensource.org
 */
package webwork.view.taglib;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;

import org.apache.commons.logging.*;
import webwork.action.ActionContext;
import webwork.action.ServletActionContext;
import webwork.dispatcher.GenericDispatcher;

import java.security.Principal;

/**
 * Instantiate an Action and execute it.
 * It is lazily executed, which means that you can set parameters
 * by using the "param" tag.
 *
 * @author Rickard 謆erg ([e-mail])
 * @version $Revision: 1.19 $
 */
public class ActionTag
        extends BeanTag {
    protected static Log log = LogFactory.getLog(ActionTag.class);

    GenericDispatcher gd;

    // BodyTag implementation ----------------------------------------
    public int doStartTag() throws JspException {
        String name = (String) findValue(nameAttr);
        if (name == null)
            throw new JspException("No action named " + nameAttr + " found. Try putting quotes around name");

        Principal oldPrincipal = ActionContext.getPrincipal();

        gd = new GenericDispatcher(name, true);
        ActionContext context = gd.prepareContext();
        ServletActionContext.setContext((HttpServletRequest) pageContext.getRequest(),
                (HttpServletResponse) pageContext.getResponse(),
                pageContext.getServletContext(),
                name);
        gd.prepareValueStack();
        ActionContext.setPrincipal(oldPrincipal);
        try {
            gd.executeAction();
            bean = gd.getActions().get(0);
        } catch (Throwable t) {
      	   String msg = "Caught throwable when instantiating action: " + name;
      	   log.error(msg, t);
      	   throw new JspException(msg + ", throwable: " + t);
        }

        if (getId() != null) {
           pageContext.setAttribute(getId(), bean);
           pageContext.setAttribute(getId(), bean, PageContext.REQUEST_SCOPE);
        }

        return EVAL_BODY_INCLUDE;
    }

    public int doEndTag() throws JspException {
        gd.finish();
        gd.finalizeContext();
        return EVAL_PAGE;
    }
}