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/*
* Copyright (C) 2000-2024 Vaadin Ltd
*
* This program is available under Vaadin Commercial License and Service Terms.
*
* See for the full
* license.
*/
package com.vaadin.server.communication;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.IOException;
import java.io.OutputStream;
import java.io.StringWriter;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.vaadin.annotations.PreserveOnRefresh;
import com.vaadin.server.LegacyApplicationUIProvider;
import com.vaadin.server.SynchronizedRequestHandler;
import com.vaadin.server.UIClassSelectionEvent;
import com.vaadin.server.UICreateEvent;
import com.vaadin.server.UIProvider;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinResponse;
import com.vaadin.server.VaadinService;
import com.vaadin.server.VaadinSession;
import com.vaadin.shared.ApplicationConstants;
import com.vaadin.shared.JsonConstants;
import com.vaadin.shared.communication.PushMode;
import com.vaadin.shared.ui.ui.Transport;
import com.vaadin.shared.ui.ui.UIConstants;
import com.vaadin.ui.UI;
import elemental.json.Json;
import elemental.json.JsonException;
import elemental.json.JsonObject;
import elemental.json.impl.JsonUtil;
/**
* Handles an initial request from the client to initialize a {@link UI}.
*
* @author Vaadin Ltd
* @since 7.1
*/
public abstract class UIInitHandler extends SynchronizedRequestHandler {
public static final String BROWSER_DETAILS_PARAMETER = "v-browserDetails";
private static final boolean IS_MPR_PRESENT;
static {
boolean mprDetected = false;
try {
Class.forName("com.vaadin.mpr.MprServlet", false,
UIInitHandler.class.getClassLoader());
mprDetected = true;
} catch (Exception e) {
}
IS_MPR_PRESENT = mprDetected;
}
protected abstract boolean isInitRequest(VaadinRequest request);
@Override
protected boolean canHandleRequest(VaadinRequest request) {
return isInitRequest(request);
}
private boolean assertUINull() {
return IS_MPR_PRESENT ? true : UI.getCurrent() == null;
}
@Override
public boolean synchronizedHandleRequest(VaadinSession session,
VaadinRequest request, VaadinResponse response) throws IOException {
try {
assert assertUINull();
// Update browser information from the request
session.getBrowser().updateRequestDetails(request);
UI uI = getBrowserDetailsUI(request, session);
session.getCommunicationManager().repaintAll(uI);
JsonObject params = Json.createObject();
params.put(UIConstants.UI_ID_PARAMETER, uI.getUIId());
String initialUIDL = getInitialUidl(request, uI);
params.put("uidl", initialUIDL);
return commitJsonResponse(request, response,
JsonUtil.stringify(params));
} catch (JsonException e) {
throw new IOException("Error producing initial UIDL", e);
}
}
/**
* Commit the JSON response. We can't write immediately to the output stream
* as we want to write only a critical notification if something goes wrong
* during the response handling.
*
* @param request
* The request that resulted in this response
* @param response
* The response to write to
* @param json
* The JSON to write
* @return true if the JSON was written successfully, false otherwise
* @throws IOException
* If there was an exception while writing to the output
*/
static boolean commitJsonResponse(VaadinRequest request,
VaadinResponse response, String json) throws IOException {
// The response was produced without errors so write it to the client
response.setContentType(JsonConstants.JSON_CONTENT_TYPE);
// Response might contain sensitive information, so prevent all forms of
// caching
response.setNoCacheHeaders();
byte[] b = json.getBytes(UTF_8);
response.setContentLength(b.length);
OutputStream outputStream = response.getOutputStream();
outputStream.write(b);
// NOTE GateIn requires the buffers to be flushed to work
outputStream.flush();
return true;
}
private UI getBrowserDetailsUI(VaadinRequest request,
VaadinSession session) {
VaadinService vaadinService = request.getService();
List uiProviders = session.getUIProviders();
UIClassSelectionEvent classSelectionEvent = new UIClassSelectionEvent(
request);
UIProvider provider = null;
Class uiClass = null;
for (UIProvider p : uiProviders) {
// Check for existing LegacyWindow
if (p instanceof LegacyApplicationUIProvider) {
LegacyApplicationUIProvider legacyProvider = (LegacyApplicationUIProvider) p;
UI existingUi = legacyProvider
.getExistingUI(classSelectionEvent);
if (existingUi != null) {
reinitUI(existingUi, request);
return existingUi;
}
}
uiClass = p.getUIClass(classSelectionEvent);
if (uiClass != null) {
provider = p;
break;
}
}
if (provider == null || uiClass == null) {
return null;
}
// Check for an existing UI based on embed id
String embedId = getEmbedId(request);
UI retainedUI = session.getUIByEmbedId(embedId);
if (retainedUI != null) {
if (vaadinService.preserveUIOnRefresh(provider,
new UICreateEvent(request, uiClass))) {
if (uiClass.isInstance(retainedUI)) {
reinitUI(retainedUI, request);
return retainedUI;
} else {
getLogger().info("Not using the preserved UI " + embedId
+ " because it is of type " + retainedUI.getClass()
+ " but " + uiClass
+ " is expected for the request.");
}
}
/*
* Previous UI without preserve on refresh will be closed when the
* new UI gets added to the session.
*/
}
// No existing UI found - go on by creating and initializing one
Integer uiId = Integer.valueOf(session.getNextUIid());
// Explicit Class.cast to detect if the UIProvider does something
// unexpected
UICreateEvent event = new UICreateEvent(request, uiClass, uiId);
UI ui = uiClass.cast(provider.createInstance(event));
// Set thread local here so it is available in init
UI.setCurrent(ui);
// Initialize some fields for a newly created UI
if (ui.getSession() != session) {
// Session already set for LegacyWindow
ui.setSession(session);
}
PushMode pushMode = provider.getPushMode(event);
if (pushMode == null) {
pushMode = session.getService().getDeploymentConfiguration()
.getPushMode();
}
ui.getPushConfiguration().setPushMode(pushMode);
Transport transport = provider.getPushTransport(event);
if (transport != null) {
ui.getPushConfiguration().setTransport(transport);
}
Exception initException = null;
try {
ui.doInit(request, uiId.intValue(), embedId);
} catch (Exception e) {
initException = e;
}
session.addUI(ui);
if (initException != null) {
ui.getSession().getCommunicationManager()
.handleConnectorRelatedException(ui, initException);
}
// Warn if the window can't be preserved
if (embedId == null
&& vaadinService.preserveUIOnRefresh(provider, event)) {
getLogger().warning("There is no embed id available for UI "
+ uiClass + " that should be preserved.");
}
return ui;
}
/**
* Constructs an embed id based on information in the request.
*
* @since 7.2
*
* @param request
* the request to get embed information from
* @return the embed id, or null if id is not available.
*
* @see UI#getEmbedId()
*/
protected String getEmbedId(VaadinRequest request) {
// Parameters sent by vaadinBootstrap.js
String windowName = request.getParameter("v-wn");
String appId = request.getParameter("v-appId");
if (windowName != null && appId != null) {
return windowName + '.' + appId;
} else {
return null;
}
}
/**
* Updates a UI that has already been initialized but is now loaded again,
* e.g. because of {@link PreserveOnRefresh}.
*
* @param ui
* @param request
*/
private void reinitUI(UI ui, VaadinRequest request) {
UI.setCurrent(ui);
ui.doRefresh(request);
}
/**
* Generates the initial UIDL message that can e.g. be included in a html
* page to avoid a separate round trip just for getting the UIDL.
*
* @param request
* the request that caused the initialization
* @param uI
* the UI for which the UIDL should be generated
* @return a string with the initial UIDL message
* @throws IOException
*/
protected String getInitialUidl(VaadinRequest request, UI uI)
throws IOException {
try (StringWriter writer = new StringWriter()) {
writer.write("{");
VaadinSession session = uI.getSession();
if (session.getConfiguration().isXsrfProtectionEnabled()) {
writer.write(getSecurityKeyUIDL(session));
}
writer.write(getPushIdUIDL(session));
new UidlWriter().write(uI, writer, false);
writer.write("}");
String initialUIDL = writer.toString();
getLogger().log(Level.FINE, "Initial UIDL:" + initialUIDL);
return initialUIDL;
}
}
/**
* Gets the security key (and generates one if needed) as UIDL.
*
* @param session
* the vaadin session to which the security key belongs
* @return the security key UIDL or "" if the feature is turned off
*/
private static String getSecurityKeyUIDL(VaadinSession session) {
String seckey = session.getCsrfToken();
return "\"" + ApplicationConstants.UIDL_SECURITY_TOKEN_ID + "\":\""
+ seckey + "\",";
}
/**
* Gets the push connection identifier as UIDL.
*
* @param session
* the vaadin session to which the security key belongs
* @return the push identifier UIDL
*/
private static String getPushIdUIDL(VaadinSession session) {
return "\"" + ApplicationConstants.UIDL_PUSH_ID + "\":\""
+ session.getPushId() + "\",";
}
private static final Logger getLogger() {
return Logger.getLogger(UIInitHandler.class.getName());
}
}
