org.fujion.model.GenericBinder Maven / Gradle / Ivy
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* fujion
* %%
* Copyright (C) 2018 Fujion Framework
* %%
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* #L%
*/
package org.fujion.model;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Observable;
import java.util.Observer;
import java.util.function.Function;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.lang.reflect.MethodUtils;
import org.fujion.ancillary.ConvertUtil;
import org.fujion.ancillary.DeferredInvocation;
import org.fujion.common.MiscUtil;
import org.fujion.component.BaseComponent;
import org.fujion.event.PropertychangeEvent;
import org.fujion.model.IBinding.IReadBinding;
import org.fujion.model.IBinding.IWriteBinding;
import org.springframework.util.Assert;
/**
* Generic data binder.
*
* @param Type of model object.
*/
public class GenericBinder implements IBinder, Observer {
private M model;
private List readBindings;
private List writeBindings;
private boolean updating;
private class GenericBinding implements IBinding {
private final String modelProperty;
private final Function readConverter;
private final Function writeConverter;
private DeferredInvocation getter;
private DeferredInvocation setter;
GenericBinding(String modelProperty, Function readConverter, Function writeConverter) {
this.modelProperty = modelProperty;
this.readConverter = readConverter;
this.writeConverter = writeConverter;
}
@Override
public void init(BaseComponent instance, String propertyName, Method getter, Method setter) {
if (this instanceof IReadBinding) {
Assert.notNull(setter, () -> "Property is not writable: " + propertyName);
this.setter = toDeferred(instance, setter, propertyName, 2);
readBindings = readBindings == null ? new ArrayList<>() : readBindings;
readBindings.add(this);
read();
} else {
this.setter = null;
}
if (this instanceof IWriteBinding) {
Assert.notNull(getter, () -> "Property is not readable: " + propertyName);
this.getter = toDeferred(instance, getter, propertyName, 1);
if (!(this instanceof IReadBinding)) {
writeBindings = writeBindings == null ? new ArrayList<>() : writeBindings;
writeBindings.add(this);
write();
}
instance.addEventListener(PropertychangeEvent.class, (event) -> {
if (!updating && ((PropertychangeEvent) event).getPropertyName().equals(propertyName)) {
write();
}
});
} else {
this.getter = null;
}
}
private DeferredInvocation toDeferred(BaseComponent instance, Method method, String name, int maxArgs) {
return method == null ? null
: new DeferredInvocation<>(instance, method,
method.getParameterCount() == maxArgs ? new Object[] { name } : null);
}
private void read() {
try {
if (model != null) {
Object value = PropertyUtils.getProperty(model, modelProperty);
value = convert(readConverter, value);
if (value != IBinder.NOVALUE) {
setter.invoke(value);
}
}
} catch (Exception e) {
throw MiscUtil.toUnchecked(e);
}
}
private void write() {
try {
if (model != null) {
Object value = convert(writeConverter, getter.invoke());
if (value != IBinder.NOVALUE) {
Class targetType = PropertyUtils.getPropertyDescriptor(model, modelProperty).getPropertyType();
value = ConvertUtil.convert(value, targetType);
BeanUtils.copyProperty(model, modelProperty, value);
}
}
} catch (Exception e) {
throw MiscUtil.toUnchecked(e);
}
}
@SuppressWarnings("unchecked")
private Object convert(Function converter, Object value) {
return converter == null ? value : ((Function) converter).apply(value);
}
}
private class ReadBinding extends GenericBinding implements IReadBinding {
ReadBinding(String modelProperty, Function readConverter) {
super(modelProperty, readConverter, null);
}
@Override
public void read() {
super.read();
}
}
private class WriteBinding extends GenericBinding implements IWriteBinding {
WriteBinding(String modelProperty, Function writeConverter) {
super(modelProperty, null, writeConverter);
}
@Override
public void write() {
super.write();
}
}
private class DualBinding extends GenericBinding implements IReadBinding, IWriteBinding {
DualBinding(String modelProperty, Function readConverter, Function writeConverter) {
super(modelProperty, readConverter, writeConverter);
}
@Override
public void read() {
super.read();
}
@Override
public void write() {
super.write();
}
}
public GenericBinder() {
this(null);
}
public GenericBinder(M model) {
setModel(model);
}
@Override
public M getModel() {
return model;
}
@Override
public void setModel(M model) {
if (this.model instanceof Observable) {
((Observable) this.model).deleteObserver(this);
}
this.model = model;
modelChanged(null);
targetChanged(null);
if (this.model instanceof Observable) {
((Observable) this.model).addObserver(this);
}
}
@Override
public IBinding read(String modelProperty, Function converter) {
return new ReadBinding(modelProperty, converter);
}
@Override
public IBinding write(String modelProperty, Function converter) {
return new WriteBinding(modelProperty, converter);
}
@Override
public IBinding dual(String modelProperty, Function readConverter, Function writeConverter) {
return new DualBinding(modelProperty, readConverter, writeConverter);
}
@Override
public void update(Observable o, Object arg) {
if (o == model) {
modelChanged(arg instanceof String ? (String) arg : null);
}
}
/**
* Call when the model has changed to update bindings.
*/
public void modelChanged() {
modelChanged(null);
}
private void targetChanged(String propertyName) {
processChanged(propertyName, false);
}
/**
* Call when a specific model property has changed.
*
* @param propertyName Name of the changed property (or null if unspecified).
*/
public void modelChanged(String propertyName) {
processChanged(propertyName, true);
}
/**
* Returns a lambda function (for use in spEL).
*
* @param instance Object instance that is target of method invocation.
* @param methodName Name of the method to invoke.
* @param args Optional additional arguments.
* @return The lambda function.
*/
public Function lambda(Object instance, String methodName, Object... args) {
int last = args == null ? 0 : args.length;
Object[] realArgs = args == null ? new Object[] { null } : Arrays.copyOf(args, last + 1);
return arg -> {
try {
realArgs[last] = arg;
return MethodUtils.invokeMethod(instance, methodName, realArgs, MiscUtil.getParameterTypes(realArgs));
} catch (Exception e) {
throw MiscUtil.toUnchecked(e);
}
};
}
/**
* Returns a lambda function that returns one of a choice of values depending on the input
* value.
*
* @param choices Possible choices to return.
* @return A lambda function for selecting among multiple choices.
*/
public Function choice(Object... choices) {
return arg -> {
int i = valueToInt(arg);
return i < 0 || i >= choices.length ? null : choices[i];
};
}
private int valueToInt(Object value) {
if (value == null) {
return -1;
}
if (value instanceof Enum) {
return ((Enum) value).ordinal();
}
for (int i = 0; i < 2; i++) {
try {
switch (i) {
case 0: // Boolean
return ConvertUtil.convert(value, Boolean.class) ? 0 : 1;
case 1: // Integer
return ConvertUtil.convert(value, Integer.class);
}
} catch (Exception e) {
// NOP
}
}
return -1;
}
private void processChanged(String propertyName, boolean read) {
List bindings = read ? readBindings : writeBindings;
if (!updating && bindings != null) {
try {
updating = true;
for (GenericBinding binding : bindings) {
if (propertyName == null || propertyName.equals(binding.modelProperty)) {
if (read) {
binding.read();
} else {
binding.write();
}
}
}
} finally {
updating = false;
}
}
}
}
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