com.vaadin.flow.server

Interface VaadinContext

All Superinterfaces:

Serializable

All Known Implementing Classes:

VaadinServletContext

public interface VaadinContext
extends Serializable

Context in which VaadinService is running. This is used to store service-scoped attributes and also works as a wrapper for context objects with properties e.g. ServletContext and PortletContext

Since:

2.0.0

Method Summary

Modifier and Type	Method and Description
default <T> T	getAttribute(Class<T> type) Returns value of the specified attribute.
<T> T	getAttribute(Class<T> type, Supplier<T> defaultValueSupplier) Returns value of the specified attribute, creating and storing a default value if attribute not present.
String	getContextParameter(String name) Returns the value for the requested parameter, or null if the parameter does not exist.
Enumeration<String>	getContextParameterNames() Returns the names of the initialization parameters as an Enumeration, or an empty Enumeration if there are o initialization parameters.
void	removeAttribute(Class<?> clazz) Removes an attribute identified by the given type.
<T> void	setAttribute(Class<T> clazz, T value) Sets the attribute value for the give type, overriding previously existing one.
default void	setAttribute(Object value) Sets the attribute value, overriding previously existing one.

Method Detail

getAttribute

<T> T getAttribute(Class<T> type,
                   Supplier<T> defaultValueSupplier)

Returns value of the specified attribute, creating and storing a default value if attribute not present.

If attribute is not yet available the defaultValueSupplier is used to get the default value which is set as the attribute value and the value is returned. The operation is executed atomically.

Parameters:

type - Type of the attribute.

defaultValueSupplier - Supplier of the default value, called when there is no value already present. May be null.

Returns:

Value of the specified attribute.

getAttribute

default <T> T getAttribute(Class<T> type)

Returns value of the specified attribute.

Parameters:

type - Type of the attribute.

Returns:

Value of the specified attribute.

setAttribute

<T> void setAttribute(Class<T> clazz,
                      T value)

Sets the attribute value for the give type, overriding previously existing one. Values are based on exact type, meaning only one attribute of given type is possible at any given time.

Parameters:

clazz - the type to associate the value with, not null

value - the attribute value to set, or null to remove the current value

Since:

setAttribute

default void setAttribute(Object value)

Sets the attribute value, overriding previously existing one. Values are based on exact type, meaning only one attribute of given type is possible at any given time.

Parameters:

value - attribute value, not null.

See Also:

for removing attributes.

removeAttribute

void removeAttribute(Class<?> clazz)

Removes an attribute identified by the given type. If the attribute does not exist, no action will be taken.

Parameters:

clazz - Attribute type.

See Also:

for setting attributes.

getContextParameterNames

Enumeration<String> getContextParameterNames()

Returns the names of the initialization parameters as an Enumeration, or an empty Enumeration if there are o initialization parameters.

Returns:

initialization parameters as a Enumeration

getContextParameter

String getContextParameter(String name)

Returns the value for the requested parameter, or null if the parameter does not exist.

Parameters:

name - name of the parameter whose value is requested

Returns:

parameter value as String or null for no parameter