Github user martin-g commented on a diff in the pull request:
https://github.com/apache/wicket/pull/249#discussion_r155464694
--- Diff:
wicket-core/src/main/java/org/apache/wicket/core/util/string/ComponentRenderer.java
---
@@ -16,35 +16,321 @@
*/
package org.apache.wicket.core.util.string;
+import java.io.Serializable;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Supplier;
+
import org.apache.wicket.Application;
import org.apache.wicket.Component;
import org.apache.wicket.MarkupContainer;
+import org.apache.wicket.Page;
+import org.apache.wicket.RuntimeConfigurationType;
+import org.apache.wicket.Session;
import org.apache.wicket.ThreadContext;
import org.apache.wicket.core.request.handler.PageProvider;
import org.apache.wicket.markup.IMarkupCacheKeyProvider;
import org.apache.wicket.markup.IMarkupResourceStreamProvider;
import org.apache.wicket.markup.MarkupNotFoundException;
import org.apache.wicket.markup.html.WebPage;
+import org.apache.wicket.mock.MockApplication;
+import org.apache.wicket.mock.MockWebRequest;
import org.apache.wicket.protocol.http.BufferedWebResponse;
+import org.apache.wicket.protocol.http.WebApplication;
+import org.apache.wicket.protocol.http.mock.MockServletContext;
+import org.apache.wicket.request.Request;
import org.apache.wicket.request.Response;
+import org.apache.wicket.request.Url;
import org.apache.wicket.request.cycle.RequestCycle;
+import org.apache.wicket.request.http.WebRequest;
+import org.apache.wicket.serialize.ISerializer;
+import org.apache.wicket.session.ISessionStore;
import org.apache.wicket.util.resource.IResourceStream;
import org.apache.wicket.util.resource.StringResourceStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A helper class for rendering components and pages.
- *
- * <p><strong>Note</strong>: {@link #renderComponent(Component)} does
<strong>not</strong>
- * support rendering {@link org.apache.wicket.markup.html.panel.Fragment}
instances!</p>
+ * <p>
+ * With the static methods of this class components and pages can be
rendered on a thread already
+ * processing an {@link Application}.
+ * <p>
+ * If you want to render independently from any web request processing
(e.g. generating an email
+ * body on a worker thread), you can create an instance of this class.<br/>
+ * You may use an existing application, create a fresh one or just use the
defaults of
+ * {@link #ComponentRenderer()} for a mocked application with sensible
defaults.
+ * <p>
+ * Note: For performance instances can and should be reused, be sure to
call {@link #destroy()} when
+ * they are no longer needed.
*/
public class ComponentRenderer
{
private static final Logger LOGGER =
LoggerFactory.getLogger(ComponentRenderer.class);
+ private WebApplication application;
+
+ /**
+ * A renderer using a default mocked application, which
+ * <ul>
+ * <li>never shares anything in a session</li>
+ * <li>never serializes anything</li>
+ * </ul>
+ */
+ public ComponentRenderer()
+ {
+ this(new MockApplication()
+ {
+ @Override
+ public RuntimeConfigurationType getConfigurationType()
+ {
+ return RuntimeConfigurationType.DEPLOYMENT;
+ }
+
+ @Override
+ protected void init()
+ {
+ super.init();
+
+ setSessionStoreProvider(() -> new
NeverSessionStore());
+ getFrameworkSettings().setSerializer(new
NeverSerializer());
+ }
+ });
+ }
+
+ /**
+ * A renderer using the given application.
+ * <p>
+ * If the application was not yet initialized - e.g. it is not reused
from an already running
+ * web container - it will be initialized.
+ */
+ public ComponentRenderer(WebApplication application)
+ {
+ this.application = application;
+
+ if (application.getName() == null)
+ {
+ // not yet initialized
+
+ inThreadContext(() -> {
+ application.setServletContext(new
MockServletContext(application, null));
+ application.setName(
+ "ComponentRenderer[" +
System.identityHashCode(ComponentRenderer.this) + "]");
+ application.initApplication();
+ });
+ }
+ }
+
+ /**
+ * Destroy this renderer.
+ */
+ public void destroy()
+ {
+ inThreadContext(() -> {
+ application.internalDestroy();
+ });
+ }
+
+ /**
+ *
+ * Collects the html generated by the rendering a component.
+ *
+ * @param component
+ * supplier of the component
+ * @return the html rendered by the panel
+ */
+ public CharSequence renderComponent(final Supplier<Component> component)
+ {
+ return renderPage(() -> new RenderPage(component.get()));
+ }
+
+ /**
+ * Collects the html generated by the rendered a component.
+ *
+ * @param page
+ * supplier of the page
+ * @return the html rendered by the panel
+ */
+ public CharSequence renderPage(final Supplier<? extends Page> page)
+ {
+ return inThreadContext(() -> {
+ WebRequest request = newWebRequest();
+
+ BufferedWebResponse response = new
BufferedWebResponse(null);
+
+ RequestCycle cycle =
application.createRequestCycle(request, response);
+
+ ThreadContext.setRequestCycle(cycle);
+
+ page.get().renderPage();
+
+ return response.getText();
+ });
+ }
+
+ /**
+ * Run the given runnable inside a valid {@link ThreadContext}.
+ *
+ * @param runnable
+ * runnable
+ */
+ private void inThreadContext(Runnable runnable)
+ {
+ inThreadContext(() -> {
+ runnable.run();
+ return null;
+ });
+ }
+
+ /**
+ * Get the result from the given supplier inside a valid {@link
ThreadContext}.
+ *
+ * @param supplier
+ * supplier
+ * @return result of {@link Supplier#get()}
+ */
+ private <T> T inThreadContext(Supplier<T> supplier)
+ {
+ ThreadContext oldContext = ThreadContext.detach();
+
+ try
+ {
+ ThreadContext.setApplication(application);
+
+ return supplier.get();
+ }
+ finally
+ {
+
+ ThreadContext.restore(oldContext);
+ }
+ }
+
+ /**
+ * Create a new request, by default a {@link MockWebRequest}.
+ */
+ protected WebRequest newWebRequest()
+ {
+ return new MockWebRequest(Url.parse("/"));
+ }
+
+ /**
+ * Never serialize.
+ */
+ private static final class NeverSerializer implements ISerializer
+ {
+ @Override
+ public byte[] serialize(Object object)
+ {
+ return null;
+ }
+
+ @Override
+ public Object deserialize(byte[] data)
+ {
+ return null;
+ }
+ }
+
+ /**
+ * Never share anything.
+ */
+ private static class NeverSessionStore implements ISessionStore
+ {
+
+ @Override
+ public Serializable getAttribute(Request request, String name)
+ {
+ return null;
+ }
+
+ @Override
+ public List<String> getAttributeNames(Request request)
+ {
+ return null;
+ }
+
+ @Override
+ public void setAttribute(Request request, String name,
Serializable value)
+ {
+ }
+
+ @Override
+ public void removeAttribute(Request request, String name)
+ {
+ }
+
+ @Override
+ public void invalidate(Request request)
+ {
+ }
+
+ @Override
+ public String getSessionId(Request request, boolean create)
+ {
+ return null;
+ }
+
+ @Override
+ public Session lookup(Request request)
+ {
+ return null;
+ }
+
+ @Override
+ public void bind(Request request, Session newSession)
+ {
+ }
+
+ @Override
+ public void flushSession(Request request, Session session)
+ {
+ }
+
+ @Override
+ public void destroy()
+ {
+ }
+
+ @Override
+ public void registerUnboundListener(UnboundListener listener)
+ {
+ }
+
+ @Override
+ public void unregisterUnboundListener(UnboundListener listener)
+ {
+ }
+
+ @Override
+ public Set<UnboundListener> getUnboundListener()
+ {
+ return null;
+ }
+
+ @Override
+ public void registerBindListener(BindListener listener)
+ {
+ }
+
+ @Override
+ public void unregisterBindListener(BindListener listener)
+ {
+ }
+
+
+ @Override
+
+ public Set<BindListener> getBindListeners()
+ {
+ return null;
+ }
+ }
+
/**
* Collects the html generated by the rendering of a page.
+ * <p>
+ * Important note: Must be called on a thread already processing a
{@link WebApplication}!
--- End diff --
What does it mean "a thread processing an application" ?
Processing a request is clear, but application is not.
---
