Include charset in text/html responses (#8777) (#9123)

Addresses #8775 for version 8.1+

server/src/main/java/com/vaadin/server/BootstrapHandler.java

@@ -363,7 +363,8 @@ public abstract class BootstrapHandler extends SynchronizedRequestHandler {
 
     private void writeBootstrapPage(VaadinResponse response, String html)
             throws IOException {
-        response.setContentType("text/html");
+        response.setContentType(
+                ApplicationConstants.CONTENT_TYPE_TEXT_HTML_UTF_8);
         try (BufferedWriter writer = new BufferedWriter(
                 new OutputStreamWriter(response.getOutputStream(), "UTF-8"))) {
             writer.append(html);
@@ -383,8 +384,8 @@ public abstract class BootstrapHandler extends SynchronizedRequestHandler {
         document.child(0).before(doctype);
 
         Element head = document.head();
-        head.appendElement("meta").attr("http-equiv", "Content-Type")
-                .attr("content", "text/html; charset=utf-8");
+        head.appendElement("meta").attr("http-equiv", "Content-Type").attr(
+                "content", ApplicationConstants.CONTENT_TYPE_TEXT_HTML_UTF_8);
 
         /*
          * Enable Chrome Frame in all versions of IE if installed.

server/src/main/java/com/vaadin/server/VaadinServlet.java

@@ -55,6 +55,7 @@ import com.vaadin.annotations.VaadinServletConfiguration;
 import com.vaadin.annotations.VaadinServletConfiguration.InitParameterName;
 import com.vaadin.sass.internal.ScssStylesheet;
 import com.vaadin.server.communication.ServletUIInitHandler;
+import com.vaadin.shared.ApplicationConstants;
 import com.vaadin.shared.JsonConstants;
 import com.vaadin.shared.Version;
 import com.vaadin.ui.UI;
@@ -585,7 +586,7 @@ public class VaadinServlet extends HttpServlet implements Constants {
                 output += "</a>";
             }
             getService().writeStringResponse(response,
-                    "text/html; charset=UTF-8", output);
+                    ApplicationConstants.CONTENT_TYPE_TEXT_HTML_UTF_8, output);
         }
     }
 

server/src/main/java/com/vaadin/server/communication/FileUploadHandler.java

@@ -36,6 +36,7 @@ import com.vaadin.server.UploadException;
 import com.vaadin.server.VaadinRequest;
 import com.vaadin.server.VaadinResponse;
 import com.vaadin.server.VaadinSession;
+import com.vaadin.shared.ApplicationConstants;
 import com.vaadin.ui.UI;
 import com.vaadin.ui.Upload.FailedEvent;
 
@@ -675,7 +676,8 @@ public class FileUploadHandler implements RequestHandler {
      */
     protected void sendUploadResponse(VaadinRequest request,
             VaadinResponse response) throws IOException {
-        response.setContentType("text/html");
+        response.setContentType(
+                ApplicationConstants.CONTENT_TYPE_TEXT_HTML_UTF_8);
         try (OutputStream out = response.getOutputStream()) {
             final PrintWriter outWriter = new PrintWriter(
                     new BufferedWriter(new OutputStreamWriter(out, "UTF-8")));

server/src/main/java/com/vaadin/ui/LoginForm.java

@@ -25,6 +25,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 import com.vaadin.server.StreamResource;
+import com.vaadin.shared.ApplicationConstants;
 import com.vaadin.shared.Registration;
 import com.vaadin.shared.ui.loginform.LoginFormConstants;
 import com.vaadin.shared.ui.loginform.LoginFormRpc;
@@ -307,7 +308,7 @@ public class LoginForm extends AbstractSingleComponentContainer {
 
         StreamResource resource = new StreamResource(new LoginStreamSource(),
                 LoginFormConstants.LOGIN_RESOURCE_NAME);
-        resource.setMIMEType("text/html; charset=utf-8");
+        resource.setMIMEType(ApplicationConstants.CONTENT_TYPE_TEXT_HTML_UTF_8);
         resource.setCacheTime(-1);
         setResource(LoginFormConstants.LOGIN_RESOURCE_NAME, resource);
 

shared/src/main/java/com/vaadin/shared/ApplicationConstants.java

@@ -179,4 +179,9 @@ public class ApplicationConstants implements Serializable {
      */
     public static final String WIDGETSET_VERSION_ID = "wsver";
 
+    /**
+     * Content type to use for text/html responses (should always be UTF-8).
+     */
+    public static final String CONTENT_TYPE_TEXT_HTML_UTF_8 = "text/html; charset=utf-8";
+
 }