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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
package org.apache.cassandra.config;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonIgnore;
import org.yaml.snakeyaml.error.YAMLException;
import org.yaml.snakeyaml.introspector.FieldProperty;
import org.yaml.snakeyaml.introspector.MethodProperty;
import org.yaml.snakeyaml.introspector.Property;
import static org.apache.cassandra.utils.FBUtilities.camelToSnake;
public class DefaultLoader implements Loader
{
@Override
public Map getProperties(Class root)
{
Map properties = new HashMap<>();
for (Class c = root; c != null; c = c.getSuperclass())
{
for (Field f : c.getDeclaredFields())
{
String name = camelToSnake(f.getName());
int modifiers = f.getModifiers();
if (!Modifier.isStatic(modifiers)
&& !f.isAnnotationPresent(JsonIgnore.class)
&& !Modifier.isTransient(modifiers)
&& Modifier.isPublic(modifiers)
&& !properties.containsKey(name))
properties.put(name, new FieldProperty(f));
}
}
try
{
PropertyDescriptor[] descriptors = Introspector.getBeanInfo(root).getPropertyDescriptors();
if (descriptors != null)
{
for (PropertyDescriptor d : descriptors)
{
String name = camelToSnake(d.getName());
Method writeMethod = d.getWriteMethod();
// if the property can't be written to, then ignore it
if (writeMethod == null || writeMethod.isAnnotationPresent(JsonIgnore.class))
continue;
// if read method exists, override the field version in case get/set does validation
if (properties.containsKey(name) && (d.getReadMethod() == null || d.getReadMethod().isAnnotationPresent(JsonIgnore.class)))
continue;
d.setName(name);
properties.put(name, new MethodPropertyPlus(d));
}
}
}
catch (IntrospectionException e)
{
throw new RuntimeException(e);
}
return properties;
}
/**
* .get() acts differently than .set() and doesn't do a good job showing the cause of the failure, this
* class rewrites to make the errors easier to reason with.
*/
private static class MethodPropertyPlus extends MethodProperty
{
private final Method readMethod;
public MethodPropertyPlus(PropertyDescriptor property)
{
super(property);
this.readMethod = property.getReadMethod();
}
@Override
public Object get(Object object)
{
if (!isReadable())
throw new YAMLException("No readable property '" + getName() + "' on class: " + object.getClass().getName());
try
{
return readMethod.invoke(object);
}
catch (IllegalAccessException e)
{
throw new YAMLException("Unable to find getter for property '" + getName() + "' on class " + object.getClass().getName(), e);
}
catch (InvocationTargetException e)
{
throw new YAMLException("Failed calling getter for property '" + getName() + "' on class " + object.getClass().getName(), e.getCause());
}
}
}
}