com.github.bordertech.wcomponents.examples.picker.SafetyContainer Maven / Gradle / Ivy
package com.github.bordertech.wcomponents.examples.picker;
import com.github.bordertech.wcomponents.AbstractMutableContainer;
import com.github.bordertech.wcomponents.ActionEscape;
import com.github.bordertech.wcomponents.ComponentModel;
import com.github.bordertech.wcomponents.RenderContext;
import com.github.bordertech.wcomponents.Request;
import com.github.bordertech.wcomponents.UIContext;
import com.github.bordertech.wcomponents.UIContextDelegate;
import com.github.bordertech.wcomponents.UIContextHolder;
import com.github.bordertech.wcomponents.WComponent;
import com.github.bordertech.wcomponents.WHorizontalRule;
import com.github.bordertech.wcomponents.WInvisibleContainer;
import com.github.bordertech.wcomponents.WebUtilities;
import com.github.bordertech.wcomponents.servlet.WServlet;
import com.github.bordertech.wcomponents.servlet.WebXmlRenderContext;
import com.github.bordertech.wcomponents.util.SystemException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;
/**
* Provides some protection against bad code when examples are being written.
*
* @author Yiannis Paschalidis
* @since 1.0.0
*/
final class SafetyContainer extends AbstractMutableContainer {
/**
* An invisible shim is used to exclude the contents from normal WComponent processing.
*/
private final WInvisibleContainer shim = new WInvisibleContainer();
/**
* An attribute key used to temporarily store any exception which occurs in the example.
*/
private static final String ERROR_KEY = "error";
/**
* Creates a SafetyContainer.
*/
SafetyContainer() {
super.add(shim);
// Set a static ID on container and it becomes a naming context for the example.
shim.setIdName("eg");
shim.setNamingContext(true);
}
/**
* Override handleRequest in order to safely process the example component, which has been excluded from normal
* WComponent processing.
*
* @param request the request being responded to.
*/
@Override
public void handleRequest(final Request request) {
if (!isInitialised()) {
getOrCreateComponentModel().delegate = new SafetyContainerDelegate(UIContextHolder.getCurrent());
setInitialised(true);
}
try {
UIContext delegate = getComponentModel().delegate;
UIContextHolder.pushContext(delegate);
try {
for (int i = 0; i < shim.getChildCount(); i++) {
shim.getChildAt(i).serviceRequest(request);
}
delegate.doInvokeLaters();
} finally {
UIContextHolder.popContext();
}
} catch (final ActionEscape e) {
// We don't want to catch ActionEscapes (e.g. ForwardExceptions)
throw e;
} catch (final Exception e) {
if (isAjaxOrTargetedRequest(request)) {
throw new SystemException(e.getMessage(), e);
} else {
setAttribute(ERROR_KEY, e);
}
}
}
/**
*
* Override preparePaintComponent to provide some protection against bad code when examples are being developed,
* resulting in invalid XML.
*
*
* Real applications should not emit HTML directly.
*
* @param request the request being responded to.
*/
@Override
protected void preparePaintComponent(final Request request) {
if (getAttribute(ERROR_KEY) == null) {
try {
for (int i = 0; i < shim.getChildCount(); i++) {
shim.getChildAt(i).preparePaint(request);
}
} catch (final Exception e) {
if (isAjaxOrTargetedRequest(request)) {
throw new SystemException(e.getMessage(), e);
} else {
setAttribute(ERROR_KEY, e);
}
}
}
}
/**
*
* Override paintComponent to provide some protection against bad code when examples are being developed, resulting
* in invalid XML.
*
*
* Real applications should not emit HTML directly.
*
* @param renderContext the RenderContext to send the output to.
*/
@Override
protected void paintComponent(final RenderContext renderContext) {
final Throwable error = (Throwable) getAttribute(ERROR_KEY);
if (error == null) {
if (renderContext instanceof WebXmlRenderContext) {
// For a WebXmlContext, we can output partial XML.
WebXmlRenderContext webRenderContext = (WebXmlRenderContext) renderContext;
final StringWriter buf = new StringWriter();
WebXmlRenderContext bufferedContext = new WebXmlRenderContext(new PrintWriter(buf));
try {
for (int i = 0; i < shim.getChildCount(); i++) {
shim.getChildAt(i).paint(bufferedContext);
}
webRenderContext.getWriter().write(buf.toString());
} catch (final Exception e) {
new ErrorComponent("Error during rendering", e).paint(renderContext);
new WHorizontalRule().paint(renderContext);
PrintWriter writer = webRenderContext.getWriter();
writer.println("\n
Partial XML:
\n\n");
writer.println(WebUtilities.encode(buf.toString()));
writer.println("\n");
}
} else {
try {
for (int i = 0; i < shim.getChildCount(); i++) {
shim.getChildAt(i).paint(renderContext);
}
} catch (final Exception e) {
new ErrorComponent("Error during rendering", e).paint(renderContext);
new WHorizontalRule().paint(renderContext);
}
}
} else {
new ErrorComponent("Error during action phase", error).paint(renderContext);
}
}
/**
* Resets the contents.
*/
public void resetContent() {
for (int i = 0; i < shim.getChildCount(); i++) {
WComponent child = shim.getChildAt(i);
child.reset();
}
removeAttribute(SafetyContainer.ERROR_KEY);
}
/**
* Remove the content.
*/
public void removeContent() {
// Remove the content by resetting the shim which also clears any static IDs from the naming context
shim.reset();
}
/**
* Override add so that components are added to the shim.
*
* @param component the component to add.
*/
@Override
public void add(final WComponent component) {
shim.add(component);
}
/**
* Override remove so that components are removed from the shim.
*
* @param component the component to remove.
*/
@Override
public void remove(final WComponent component) {
shim.remove(component);
}
/**
* Override removeAll so that all components are removed from the shim.
*/
@Override
public void removeAll() {
shim.removeAll();
}
/**
* {@inheritDoc}
*/
@Override // For type safety only
protected SafetyContainerModel getComponentModel() {
return (SafetyContainerModel) super.getComponentModel();
}
/**
* {@inheritDoc}
*/
@Override // For type safety only
protected SafetyContainerModel getOrCreateComponentModel() {
return (SafetyContainerModel) super.getOrCreateComponentModel();
}
/**
* Creates a new component model appropriate for this component.
*
* @return a new SafetyContainerModel.
*/
@Override
protected ComponentModel newComponentModel() {
return new SafetyContainerModel();
}
/**
* Holds the extrinsic state information of the SafetyContainer.
*/
public static final class SafetyContainerModel extends ComponentModel {
private UIContext delegate;
}
/**
* We need to keep the Example's invoke later actions separate from the rest, so this delegate keeps its own list of
* runnables.
*/
private static final class SafetyContainerDelegate extends UIContextDelegate {
/**
* A list of runnables to invoke later.
*/
private transient List invokeLaterRunnables;
/**
* Creates a SafetyContainerDelegate.
*
* @param uic the backing UIContext.
*/
private SafetyContainerDelegate(final UIContext uic) {
super(uic);
}
@Override
public void invokeLater(final Runnable runnable) {
if (invokeLaterRunnables == null) {
invokeLaterRunnables = new ArrayList<>();
}
invokeLaterRunnables.add(runnable);
}
/**
* Runs the runnables that were added using {@link #invokeLater(Runnable)}.
*/
@Override
public void doInvokeLaters() {
if (invokeLaterRunnables == null) {
return;
}
// The Runnables we are about to run may add their own invoke later
// runnables, so
// loop to make sure we process them all.
while (!invokeLaterRunnables.isEmpty()) {
final List runnables = new ArrayList<>();
runnables.addAll(invokeLaterRunnables);
invokeLaterRunnables.clear();
for (final Runnable run : runnables) {
run.run();
}
}
}
}
/**
* @param request the request being processed
* @return true if request is AJAX or Target request
*/
private boolean isAjaxOrTargetedRequest(final Request request) {
return request.getParameter(WServlet.AJAX_TRIGGER_PARAM_NAME) != null
|| request.getParameter(WServlet.TARGET_ID_PARAM_NAME) != null;
}
}