org.apache.commons.chain.web.servlet: public class: ChainProcessor

org.apache.commons.chain.web.servlet
public class: ChainProcessor [javadoc | source]

java.lang.Object
   javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
         org.apache.commons.chain.web.ChainServlet
            org.apache.commons.chain.web.servlet.ChainProcessor

All Implemented Interfaces:
Serializable, Servlet, ServletConfig

Custom subclass of ChainServlet that also dispatches incoming requests to a configurable Command loaded from the specified Catalog .

In addition to the servlet init parameters supported by ChainServlet , this class supports the following additional parameters:

org.apache.commons.chain.CATALOG - Name of the catalog from which to acquire commands to be executed. If not specified, the default catalog for this application will be used.
org.apache.commons.chain.COMMAND - Name of the Command (looked up in our configured Catalog used to process all incoming servlet requests. If not specified, defaults to command.

Also, the org.apache.commons.chain.CONFIG_ATTR init parameter is also used to identify the org.apache.commons.chain.Context attribute under which our configured Catalog will be made available to Command s processing our requests, in addition to its definition of the ServletContext attribute key under which the Catalog is available.

Field Summary
public static final String	CATALOG	The name of the servlet init parameter containing the name of the Catalog to use for processing incoming requests.
public static final String	CATALOG_DEFAULT	The default request attribute under which we expose the Catalog being used to subordinate Command s.
public static final String	COMMAND	The name of the servlet init parameter containing the name of the Command (loaded from our configured Catalog to use for processing each incoming request.

Fields inherited from org.apache.commons.chain.web.ChainServlet:
CONFIG_ATTR, CONFIG_CLASS_RESOURCE, CONFIG_WEB_RESOURCE, RULE_SET

Method from org.apache.commons.chain.web.servlet.ChainProcessor Summary:
destroy, init, service

Methods from org.apache.commons.chain.web.ChainServlet:
destroy, init, service

Methods from javax.servlet.http.HttpServlet:
service

Methods from javax.servlet.GenericServlet:
destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log, service

Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from org.apache.commons.chain.web.servlet.ChainProcessor Detail:
public void destroy() { // --------------------------------------------------------- Servlet Methods super.destroy(); attribute = null; catalog = null; command = null; } Clean up as this application is shut down.
public void init() throws ServletException { super.init(); attribute = getServletConfig().getInitParameter(CONFIG_ATTR); catalog = getServletConfig().getInitParameter(CATALOG); command = getServletConfig().getInitParameter(COMMAND); if (command == null) { command = COMMAND_DEFAULT; } } Cache the name of the command we should execute for each request.
public void service(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { ServletWebContext context = new ServletWebContext(getServletContext(), request, response); Catalog theCatalog = null; if (attribute != null) { theCatalog = (Catalog) getServletContext().getAttribute (this.attribute); } else if (catalog != null) { theCatalog = CatalogFactory.getInstance().getCatalog(catalog); } else { theCatalog = CatalogFactory.getInstance().getCatalog(); } if (attribute == null) { request.setAttribute(CATALOG_DEFAULT, theCatalog); } Command command = theCatalog.getCommand(this.command); try { command.execute(context); } catch (Exception e) { throw new ServletException(e); } } Configure a ServletWebContext for the current request, and pass it to the `execute()` method of the specified Command , loaded from our configured Catalog .

Method from org.apache.commons.chain.web.servlet.ChainProcessor Detail:

 public  void destroy() {
    // --------------------------------------------------------- Servlet Methods
        super.destroy();
        attribute = null;
        catalog = null;
        command = null;
}

Clean up as this application is shut down.

 public  void init() throws ServletException {
        super.init();
        attribute = getServletConfig().getInitParameter(CONFIG_ATTR);
        catalog = getServletConfig().getInitParameter(CATALOG);
        command = getServletConfig().getInitParameter(COMMAND);
        if (command == null) {
            command = COMMAND_DEFAULT;
        }
}

Cache the name of the command we should execute for each request.

 public  void service(HttpServletRequest request,
    HttpServletResponse response) throws IOException, ServletException {
        ServletWebContext context =
            new ServletWebContext(getServletContext(), request, response);
        Catalog theCatalog = null;
        if (attribute != null) {
            theCatalog = (Catalog) getServletContext().getAttribute
                (this.attribute);
        } else if (catalog != null) {
            theCatalog = CatalogFactory.getInstance().getCatalog(catalog);
        } else {
            theCatalog = CatalogFactory.getInstance().getCatalog();
        }
        if (attribute == null) {
            request.setAttribute(CATALOG_DEFAULT, theCatalog);
        }
        Command command = theCatalog.getCommand(this.command);
        try {
            command.execute(context);
        } catch (Exception e) {
            throw new ServletException(e);
        }
}

Configure a ServletWebContext for the current request, and pass it to the execute() method of the specified Command , loaded from our configured Catalog .