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Diffstat (limited to 'server/src/com/vaadin/data/util/TransactionalPropertyWrapper.java')
-rw-r--r-- | server/src/com/vaadin/data/util/TransactionalPropertyWrapper.java | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/server/src/com/vaadin/data/util/TransactionalPropertyWrapper.java b/server/src/com/vaadin/data/util/TransactionalPropertyWrapper.java new file mode 100644 index 0000000000..d042bfaac2 --- /dev/null +++ b/server/src/com/vaadin/data/util/TransactionalPropertyWrapper.java @@ -0,0 +1,114 @@ +/* +@VaadinApache2LicenseForJavaFiles@ + */ +package com.vaadin.data.util; + +import com.vaadin.data.Property; +import com.vaadin.data.Property.ValueChangeEvent; +import com.vaadin.data.Property.ValueChangeNotifier; + +/** + * Wrapper class that helps implement two-phase commit for a non-transactional + * property. + * + * When accessing the property through the wrapper, getting and setting the + * property value take place immediately. However, the wrapper keeps track of + * the old value of the property so that it can be set for the property in case + * of a roll-back. This can result in the underlying property value changing + * multiple times (first based on modifications made by the application, then + * back upon roll-back). + * + * Value change events on the {@link TransactionalPropertyWrapper} are only + * fired at the end of a successful transaction, whereas listeners attached to + * the underlying property may receive multiple value change events. + * + * @see com.vaadin.data.Property.Transactional + * + * @author Vaadin Ltd + * @version @version@ + * @since 7.0 + * + * @param <T> + */ +public class TransactionalPropertyWrapper<T> extends AbstractProperty<T> + implements ValueChangeNotifier, Property.Transactional<T> { + + private Property<T> wrappedProperty; + private boolean inTransaction = false; + private boolean valueChangePending; + private T valueBeforeTransaction; + + public TransactionalPropertyWrapper(Property<T> wrappedProperty) { + this.wrappedProperty = wrappedProperty; + if (wrappedProperty instanceof ValueChangeNotifier) { + ((ValueChangeNotifier) wrappedProperty) + .addListener(new ValueChangeListener() { + + @Override + public void valueChange(ValueChangeEvent event) { + fireValueChange(); + } + }); + } + } + + @Override + public Class getType() { + return wrappedProperty.getType(); + } + + @Override + public T getValue() { + return wrappedProperty.getValue(); + } + + @Override + public void setValue(Object newValue) throws ReadOnlyException { + // Causes a value change to be sent to this listener which in turn fires + // a new value change event for this property + wrappedProperty.setValue(newValue); + } + + @Override + public void startTransaction() { + inTransaction = true; + valueBeforeTransaction = getValue(); + } + + @Override + public void commit() { + endTransaction(); + } + + @Override + public void rollback() { + try { + wrappedProperty.setValue(valueBeforeTransaction); + } finally { + valueChangePending = false; + endTransaction(); + } + } + + protected void endTransaction() { + inTransaction = false; + valueBeforeTransaction = null; + if (valueChangePending) { + fireValueChange(); + } + } + + @Override + protected void fireValueChange() { + if (inTransaction) { + valueChangePending = true; + } else { + super.fireValueChange(); + } + } + + public Property<T> getWrappedProperty() { + return wrappedProperty; + } + +} |