org.apache.commons.configuration2.beanutils.XMLBeanDeclaration Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of commons-configuration2 Show documentation
Show all versions of commons-configuration2 Show documentation
Tools to assist in the reading of configuration/preferences files in
various formats
/*
* 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.commons.configuration2.beanutils;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.configuration2.BaseHierarchicalConfiguration;
import org.apache.commons.configuration2.HierarchicalConfiguration;
import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
import org.apache.commons.configuration2.interpol.ConfigurationInterpolator;
import org.apache.commons.configuration2.tree.NodeHandler;
import org.apache.commons.lang3.StringUtils;
/**
*
* An implementation of the {@code BeanDeclaration} interface that is
* suitable for XML configuration files.
*
*
* This class defines the standard layout of a bean declaration in an XML
* configuration file. Such a declaration must look like the following example
* fragment:
*
*
*
* ...
* <personBean config-class="my.model.PersonBean"
* lastName="Doe" firstName="John">
* <config-constrarg config-value="ID03493" config-type="java.lang.String"/>
* <address config-class="my.model.AddressBean"
* street="21st street 11" zip="1234"
* city="TestCity"/>
* </personBean>
*
*
*
* The bean declaration can be contained in an arbitrary element. Here it is the
* {@code personBean} element. In the attributes of this element
* there can occur some reserved attributes, which have the following meaning:
*
*
* - {@code config-class}
* - Here the full qualified name of the bean's class can be specified. An
* instance of this class will be created. If this attribute is not specified,
* the bean class must be provided in another way, e.g. as the
* {@code defaultClass} passed to the {@code BeanHelper} class.
* - {@code config-factory}
* - This attribute can contain the name of the
* {@link BeanFactory} that should be used for creating the bean.
* If it is defined, a factory with this name must have been registered at the
* {@code BeanHelper} class. If this attribute is missing, the default
* bean factory will be used.
* - {@code config-factoryParam}
* - With this attribute a parameter can be specified that will be passed to
* the bean factory. This may be useful for custom bean factories.
*
*
* All further attributes starting with the {@code config-} prefix are
* considered as meta data and will be ignored. All other attributes are treated
* as properties of the bean to be created, i.e. corresponding setter methods of
* the bean will be invoked with the values specified here.
*
*
* If the bean to be created has also some complex properties (which are itself
* beans), their values cannot be initialized from attributes. For this purpose
* nested elements can be used. The example listing shows how an address bean
* can be initialized. This is done in a nested element whose name must match
* the name of a property of the enclosing bean declaration. The format of this
* nested element is exactly the same as for the bean declaration itself, i.e.
* it can have attributes defining meta data or bean properties and even further
* nested elements for complex bean properties.
*
*
* If the bean should be created using a specific constructor, the constructor
* arguments have to be specified. This is done by an arbitrary number of
* nested {@code } elements. Each element can either have the
* {@code config-value} attribute - then it defines a simple value - or must be
* again a bean declaration (conforming to the format defined here) defining
* the complex value of this constructor argument.
*
*
* A {@code XMLBeanDeclaration} object is usually created from a
* {@code HierarchicalConfiguration}. From this it will derive a
* {@code SubnodeConfiguration}, which is used to access the needed
* properties. This subnode configuration can be obtained using the
* {@link #getConfiguration()} method. All of its properties can
* be accessed in the usual way. To ensure that the property keys used by this
* class are understood by the configuration, the default expression engine will
* be set.
*
*
* @since 1.3
* @version $Id: XMLBeanDeclaration.java 1790899 2017-04-10 21:56:46Z ggregory $
*/
public class XMLBeanDeclaration implements BeanDeclaration
{
/** Constant for the prefix of reserved attributes. */
public static final String RESERVED_PREFIX = "config-";
/** Constant for the prefix for reserved attributes.*/
public static final String ATTR_PREFIX = "[@" + RESERVED_PREFIX;
/** Constant for the bean class attribute. */
public static final String ATTR_BEAN_CLASS = ATTR_PREFIX + "class]";
/** Constant for the bean factory attribute. */
public static final String ATTR_BEAN_FACTORY = ATTR_PREFIX + "factory]";
/** Constant for the bean factory parameter attribute. */
public static final String ATTR_FACTORY_PARAM = ATTR_PREFIX
+ "factoryParam]";
/** Constant for the name of the bean class attribute. */
private static final String ATTR_BEAN_CLASS_NAME = RESERVED_PREFIX + "class";
/** Constant for the name of the element for constructor arguments. */
private static final String ELEM_CTOR_ARG = RESERVED_PREFIX + "constrarg";
/**
* Constant for the name of the attribute with the value of a constructor
* argument.
*/
private static final String ATTR_CTOR_VALUE = RESERVED_PREFIX + "value";
/**
* Constant for the name of the attribute with the data type of a
* constructor argument.
*/
private static final String ATTR_CTOR_TYPE = RESERVED_PREFIX + "type";
/** Stores the associated configuration. */
private final HierarchicalConfiguration configuration;
/** Stores the configuration node that contains the bean declaration. */
private final NodeData node;
/** The name of the default bean class. */
private final String defaultBeanClassName;
/**
* Creates a new instance of {@code XMLBeanDeclaration} and initializes it
* from the given configuration. The passed in key points to the bean
* declaration.
*
* @param config the configuration (must not be null)
* @param key the key to the bean declaration (this key must point to
* exactly one bean declaration or a {@code IllegalArgumentException}
* exception will be thrown)
* @param the node type of the configuration
* @throws IllegalArgumentException if required information is missing to
* construct the bean declaration
*/
public XMLBeanDeclaration(HierarchicalConfiguration config, String key)
{
this(config, key, false);
}
/**
* Creates a new instance of {@code XMLBeanDeclaration} and initializes it
* from the given configuration supporting optional declarations.
*
* @param config the configuration (must not be null)
* @param key the key to the bean declaration
* @param optional a flag whether this declaration is optional; if set to
* true, no exception will be thrown if the passed in key is
* undefined
* @param the node type of the configuration
* @throws IllegalArgumentException if required information is missing to
* construct the bean declaration
*/
public XMLBeanDeclaration(HierarchicalConfiguration config, String key,
boolean optional)
{
this(config, key, optional, null);
}
/**
* Creates a new instance of {@code XMLBeanDeclaration} and initializes it
* from the given configuration supporting optional declarations and a
* default bean class name. The passed in key points to the bean
* declaration. If the key does not exist and the boolean argument is
* true, the declaration is initialized with an empty configuration.
* It is possible to create objects from such an empty declaration if a
* default class is provided. If the key on the other hand has multiple
* values or is undefined and the boolean argument is false, a
* {@code IllegalArgumentException} exception will be thrown. It is possible
* to set a default bean class name; this name is used if the configuration
* does not contain a bean class.
*
* @param config the configuration (must not be null)
* @param key the key to the bean declaration
* @param optional a flag whether this declaration is optional; if set to
* true, no exception will be thrown if the passed in key is
* undefined
* @param defBeanClsName a default bean class name
* @param the node type of the configuration
* @throws IllegalArgumentException if required information is missing to
* construct the bean declaration
* @since 2.0
*/
public XMLBeanDeclaration(HierarchicalConfiguration config, String key,
boolean optional, String defBeanClsName)
{
if (config == null)
{
throw new IllegalArgumentException(
"Configuration must not be null!");
}
HierarchicalConfiguration tmpconfiguration;
try
{
tmpconfiguration = config.configurationAt(key);
}
catch (ConfigurationRuntimeException iex)
{
// If we reach this block, the key does not have exactly one value
if (!optional || config.getMaxIndex(key) > 0)
{
throw iex;
}
tmpconfiguration = new BaseHierarchicalConfiguration();
}
this.node = createNodeDataFromConfiguration(tmpconfiguration);
this.configuration = tmpconfiguration;
defaultBeanClassName = defBeanClsName;
initSubnodeConfiguration(getConfiguration());
}
/**
* Creates a new instance of {@code XMLBeanDeclaration} and
* initializes it from the given configuration. The configuration's root
* node must contain the bean declaration.
*
* @param config the configuration with the bean declaration
* @param the node type of the configuration
*/
public XMLBeanDeclaration(HierarchicalConfiguration config)
{
this(config, (String) null);
}
/**
* Creates a new instance of {@code XMLBeanDeclaration} and
* initializes it with the configuration node that contains the bean
* declaration. This constructor is used internally.
*
* @param config the configuration
* @param node the node with the bean declaration.
*/
XMLBeanDeclaration(HierarchicalConfiguration config,
NodeData node)
{
this.node = node;
configuration = config;
defaultBeanClassName = null;
initSubnodeConfiguration(config);
}
/**
* Returns the configuration object this bean declaration is based on.
*
* @return the associated configuration
*/
public HierarchicalConfiguration getConfiguration()
{
return configuration;
}
/**
* Returns the name of the default bean class. This class is used if no bean
* class is specified in the configuration. It may be null if no
* default class was set.
*
* @return the default bean class name
* @since 2.0
*/
public String getDefaultBeanClassName()
{
return defaultBeanClassName;
}
/**
* Returns the name of the bean factory. This information is fetched from
* the {@code config-factory} attribute.
*
* @return the name of the bean factory
*/
@Override
public String getBeanFactoryName()
{
return getConfiguration().getString(ATTR_BEAN_FACTORY, null);
}
/**
* Returns a parameter for the bean factory. This information is fetched
* from the {@code config-factoryParam} attribute.
*
* @return the parameter for the bean factory
*/
@Override
public Object getBeanFactoryParameter()
{
return getConfiguration().getProperty(ATTR_FACTORY_PARAM);
}
/**
* Returns the name of the class of the bean to be created. This information
* is obtained from the {@code config-class} attribute.
*
* @return the name of the bean's class
*/
@Override
public String getBeanClassName()
{
return getConfiguration().getString(ATTR_BEAN_CLASS, getDefaultBeanClassName());
}
/**
* Returns a map with the bean's (simple) properties. The properties are
* collected from all attribute nodes, which are not reserved.
*
* @return a map with the bean's properties
*/
@Override
public Map getBeanProperties()
{
Map props = new HashMap<>();
for (String key : getAttributeNames())
{
if (!isReservedAttributeName(key))
{
props.put(key, interpolate(getNode().getAttribute(key)));
}
}
return props;
}
/**
* Returns a map with bean declarations for the complex properties of the
* bean to be created. These declarations are obtained from the child nodes
* of this declaration's root node.
*
* @return a map with bean declarations for complex properties
*/
@Override
public Map getNestedBeanDeclarations()
{
Map nested = new HashMap<>();
for (NodeData child : getNode().getChildren())
{
if (!isReservedChildName(child.nodeName()))
{
if (nested.containsKey(child.nodeName()))
{
Object obj = nested.get(child.nodeName());
List list;
if (obj instanceof List)
{
// Safe because we created the lists ourselves.
@SuppressWarnings("unchecked")
List tmpList = (List) obj;
list = tmpList;
}
else
{
list = new ArrayList<>();
list.add((BeanDeclaration) obj);
nested.put(child.nodeName(), list);
}
list.add(createBeanDeclaration(child));
}
else
{
nested.put(child.nodeName(), createBeanDeclaration(child));
}
}
}
return nested;
}
/**
* {@inheritDoc} This implementation processes all child nodes with the name
* {@code config-constrarg}. If such a node has a {@code config-class}
* attribute, it is considered a nested bean declaration; otherwise it is
* interpreted as a simple value. If no nested constructor argument
* declarations are found, result is an empty collection.
*/
@Override
public Collection getConstructorArgs()
{
Collection args = new LinkedList<>();
for (NodeData child : getNode().getChildren(ELEM_CTOR_ARG))
{
args.add(createConstructorArg(child));
}
return args;
}
/**
* Performs interpolation for the specified value. This implementation will
* interpolate against the current subnode configuration's parent. If sub
* classes need a different interpolation mechanism, they should override
* this method.
*
* @param value the value that is to be interpolated
* @return the interpolated value
*/
protected Object interpolate(Object value)
{
ConfigurationInterpolator interpolator =
getConfiguration().getInterpolator();
return (interpolator != null) ? interpolator.interpolate(value) : value;
}
/**
* Checks if the specified child node name is reserved and thus should be
* ignored. This method is called when processing child nodes of this bean
* declaration. It is then possible to ignore some nodes with a specific
* meaning. This implementation delegates to {@link #isReservedName(String)}
* .
*
* @param name the name of the child node to be checked
* @return a flag whether this name is reserved
* @since 2.0
*/
protected boolean isReservedChildName(String name)
{
return isReservedName(name);
}
/**
* Checks if the specified attribute name is reserved and thus does not
* point to a property of the bean to be created. This method is called when
* processing the attributes of this bean declaration. It is then possible
* to ignore some attributes with a specific meaning. This implementation
* delegates to {@link #isReservedName(String)}.
*
* @param name the name of the attribute to be checked
* @return a flag whether this name is reserved
* @since 2.0
*/
protected boolean isReservedAttributeName(String name)
{
return isReservedName(name);
}
/**
* Checks if the specified name of a node or attribute is reserved and thus
* should be ignored. This method is called per default by the methods for
* checking attribute and child node names. It checks whether the passed in
* name starts with the reserved prefix.
*
* @param name the name to be checked
* @return a flag whether this name is reserved
*/
protected boolean isReservedName(String name)
{
return name == null || name.startsWith(RESERVED_PREFIX);
}
/**
* Returns a set with the names of the attributes of the configuration node
* holding the data of this bean declaration.
*
* @return the attribute names of the underlying configuration node
*/
protected Set getAttributeNames()
{
return getNode().getAttributes();
}
/**
* Returns the data about the associated node.
*
* @return the node with the bean declaration
*/
NodeData getNode()
{
return node;
}
/**
* Creates a new {@code BeanDeclaration} for a child node of the
* current configuration node. This method is called by
* {@code getNestedBeanDeclarations()} for all complex sub properties
* detected by this method. Derived classes can hook in if they need a
* specific initialization. This base implementation creates a
* {@code XMLBeanDeclaration} that is properly initialized from the
* passed in node.
*
* @param node the child node, for which a {@code BeanDeclaration} is
* to be created
* @return the {@code BeanDeclaration} for this child node
*/
BeanDeclaration createBeanDeclaration(NodeData node)
{
for (HierarchicalConfiguration config : getConfiguration()
.configurationsAt(node.escapedNodeName(getConfiguration())))
{
if (node.matchesConfigRootNode(config))
{
return new XMLBeanDeclaration(config, node);
}
}
throw new ConfigurationRuntimeException("Unable to match node for "
+ node.nodeName());
}
/**
* Initializes the internally managed sub configuration. This method
* will set some default values for some properties.
*
* @param conf the configuration to initialize
*/
private void initSubnodeConfiguration(HierarchicalConfiguration conf)
{
conf.setExpressionEngine(null);
}
/**
* Creates a {@code ConstructorArg} object for the specified configuration
* node.
*
* @param child the configuration node
* @return the corresponding {@code ConstructorArg} object
*/
private ConstructorArg createConstructorArg(NodeData child)
{
String type = getAttribute(child, ATTR_CTOR_TYPE);
if (isBeanDeclarationArgument(child))
{
return ConstructorArg.forValue(
getAttribute(child, ATTR_CTOR_VALUE), type);
}
else
{
return ConstructorArg.forBeanDeclaration(
createBeanDeclaration(child), type);
}
}
/**
* Helper method for obtaining an attribute of a configuration node.
* This method also takes interpolation into account.
*
* @param nd the node
* @param attr the name of the attribute
* @return the string value of this attribute (can be null)
*/
private String getAttribute(NodeData nd, String attr)
{
Object value = nd.getAttribute(attr);
return (value == null) ? null : String.valueOf(interpolate(value));
}
/**
* Checks whether the constructor argument represented by the given
* configuration node is a bean declaration.
*
* @param nd the configuration node in question
* @return a flag whether this constructor argument is a bean declaration
*/
private static boolean isBeanDeclarationArgument(NodeData nd)
{
return !nd.getAttributes().contains(ATTR_BEAN_CLASS_NAME);
}
/**
* Creates a {@code NodeData} object from the root node of the given
* configuration.
*
* @param config the configuration
* @param the type of the nodes
* @return the {@code NodeData} object
*/
private static NodeData createNodeDataFromConfiguration(
HierarchicalConfiguration config)
{
NodeHandler handler = config.getNodeModel().getNodeHandler();
return new NodeData<>(handler.getRootNode(), handler);
}
/**
* An internally used helper class which wraps the node with the bean
* declaration and the corresponding node handler.
*
* @param the type of the node
*/
static class NodeData
{
/** The wrapped node. */
private final T node;
/** The node handler for interacting with this node. */
private final NodeHandler handler;
/**
* Creates a new instance of {@code NodeData}.
*
* @param nd the node
* @param hndlr the handler
*/
public NodeData(T nd, NodeHandler hndlr)
{
node = nd;
handler = hndlr;
}
/**
* Returns the name of the wrapped node.
*
* @return the node name
*/
public String nodeName()
{
return handler.nodeName(node);
}
/**
* Returns the unescaped name of the node stored in this data object.
* This method handles the case that the node name may contain reserved
* characters with a special meaning for the current expression engine.
* In this case, the characters affected have to be escaped accordingly.
*
* @param config the configuration
* @return the escaped node name
*/
public String escapedNodeName(HierarchicalConfiguration config)
{
return config.getExpressionEngine().nodeKey(node,
StringUtils.EMPTY, handler);
}
/**
* Returns a list with the children of the wrapped node, again wrapped
* into {@code NodeData} objects.
*
* @return a list with the children
*/
public List> getChildren()
{
return wrapInNodeData(handler.getChildren(node));
}
/**
* Returns a list with the children of the wrapped node with the given
* name, again wrapped into {@code NodeData} objects.
*
* @param name the name of the desired child nodes
* @return a list with the children with this name
*/
public List> getChildren(String name)
{
return wrapInNodeData(handler.getChildren(node, name));
}
/**
* Returns a set with the names of the attributes of the wrapped node.
*
* @return the attribute names of this node
*/
public Set getAttributes()
{
return handler.getAttributes(node);
}
/**
* Returns the value of the attribute with the given name of the wrapped
* node.
*
* @param key the key of the attribute
* @return the value of this attribute
*/
public Object getAttribute(String key)
{
return handler.getAttributeValue(node, key);
}
/**
* Returns a flag whether the wrapped node is the root node of the
* passed in configuration.
*
* @param config the configuration
* @return a flag whether this node is the configuration's root node
*/
public boolean matchesConfigRootNode(HierarchicalConfiguration config)
{
return config.getNodeModel().getNodeHandler().getRootNode()
.equals(node);
}
/**
* Wraps the passed in list of nodes in {@code NodeData} objects.
*
* @param nodes the list with nodes
* @return the wrapped nodes
*/
private List> wrapInNodeData(List nodes)
{
List> result = new ArrayList<>(nodes.size());
for (T node : nodes)
{
result.add(new NodeData<>(node, handler));
}
return result;
}
}
}