Package com.vaadin.flow.component

Class Html

java.lang.Object

com.vaadin.flow.component.Component

com.vaadin.flow.component.Html

All Implemented Interfaces:

AttachNotifier, DetachNotifier, HasElement, HasStyle, Serializable

public class Html
extends Component

A component which encapsulates a given HTML fragment with a single root element.

Note that it is the developer's responsibility to sanitize and remove any dangerous parts of the HTML before sending it to the user through this component. Passing raw input data to the user will possibly lead to cross-site scripting attacks.

This component does not expand the HTML fragment into a server side DOM tree so you cannot traverse or modify the HTML on the server. The root element can be accessed through Component.getElement() and the inner HTML through getInnerHtml().

The HTML fragment cannot be changed after creation. You should create a new instance to encapsulate another fragment.

Note that this component doesn't support svg element as a root node. See separate Svg component if you want to display SVG images.

Since:

1.0

Author:

Vaadin Ltd

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
Html(Signal<String> htmlSignal)	Creates an instance based on the given HTML fragment signal.
Html(InputStream stream)	Creates an instance based on the HTML fragment read from the stream.
Html(String outerHtml)	Creates an instance based on the given HTML fragment.

Method Summary

Modifier and Type	Method	Description
void	bindHtmlContent(Signal<String> htmlSignal)	Binds a Signal's value to this component's HTML content (outer HTML) and keeps the content synchronized with the signal value while the component is attached.
String	getInnerHtml()	Gets the inner HTML, i.e.
void	setHtmlContent(String html)	Sets the content based on the given HTML fragment.

Methods inherited from class com.vaadin.flow.component.Component

addListener, bindVisible, findAncestor, fireEvent, from, get, getChildren, getElement, getEventBus, getId, getListeners, getLocale, getParent, getTranslation, getTranslation, getTranslation, getTranslation, getTranslation, getTranslation, getUI, hasListener, isAttached, isTemplateMapped, isVisible, onAttach, onDetach, onEnabledStateChanged, removeFromParent, scrollIntoView, scrollIntoView, set, setElement, setId, setVisible

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.vaadin.flow.component.AttachNotifier

addAttachListener

Methods inherited from interface com.vaadin.flow.component.DetachNotifier

addDetachListener

Methods inherited from interface com.vaadin.flow.component.HasStyle

addClassName, addClassNames, bindClassName, getClassName, getClassNames, getStyle, hasClassName, removeClassName, removeClassNames, setClassName, setClassName

Constructor Details

Html

public Html(InputStream stream)

Creates an instance based on the HTML fragment read from the stream. The fragment must have exactly one root element.

A best effort is done to parse broken HTML but no guarantees are given for how invalid HTML is handled.

Any heading or trailing whitespace is removed while parsing but any whitespace inside the root tag is preserved.

Parameters:

stream - the input stream which provides the HTML in UTF-8

Throws:

UncheckedIOException - if reading the stream fails

Html

public Html(String outerHtml)

Creates an instance based on the given HTML fragment. The fragment must have exactly one root element.

A best effort is done to parse broken HTML but no guarantees are given for how invalid HTML is handled.

Any heading or trailing whitespace is removed while parsing but any whitespace inside the root tag is preserved.

Parameters:

outerHtml - the HTML to wrap

Html

public Html(Signal<String> htmlSignal)

Creates an instance based on the given HTML fragment signal. The signal's current value must have exactly one root element. Subsequent changes to the signal will update the component's content (root tag cannot be changed after creation).

Parameters:

htmlSignal - the signal that provides the HTML outer content

Throws:

IllegalArgumentException - if the signal is null or its current value is null or empty, or doesn't have exactly one root element

Method Details

setHtmlContent

public void setHtmlContent(String html)

Sets the content based on the given HTML fragment. The fragment must have exactly one root element, which matches the existing one.

A best effort is done to parse broken HTML but no guarantees are given for how invalid HTML is handled.

Any heading or trailing whitespace is removed while parsing but any whitespace inside the root tag is preserved.

Parameters:

html - the HTML to wrap

getInnerHtml

public String getInnerHtml()

Gets the inner HTML, i.e. everything inside the root element.

Returns:

the inner HTML, not null

bindHtmlContent

public void bindHtmlContent(Signal<String> htmlSignal)

Binds a Signal's value to this component's HTML content (outer HTML) and keeps the content synchronized with the signal value while the component is attached. When the component is detached, signal value changes have no effect.

While a Signal is bound to the HTML content, any attempt to set the HTML content manually via setHtmlContent(String) throws BindingActiveException. The same happens when trying to bind a new Signal while one is already bound.

The first value of the signal must have exactly one root element. When updating the content, the root tag name must remain the same as the component's current root tag.

Parameters:

htmlSignal - the signal to bind, not null

Throws:

BindingActiveException - thrown when there is already an existing binding