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
The newest version!
/*
* 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 java.util.function.Function;
import java.util.stream.Collectors;
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
*/
public class XMLBeanDeclaration implements BeanDeclaration {
/**
* An internal 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 nodeHandler;
/**
* Constructs a new instance of {@code NodeData}.
*
* @param node the node
* @param nodeHandler the node handler
*/
NodeData(final T node, final NodeHandler nodeHandler) {
this.node = node;
this.nodeHandler = nodeHandler;
}
/**
* 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
*/
String escapedNodeName(final HierarchicalConfiguration config) {
return config.getExpressionEngine().nodeKey(node, StringUtils.EMPTY, nodeHandler);
}
/**
* Gets 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
*/
Object getAttribute(final String key) {
return nodeHandler.getAttributeValue(node, key);
}
/**
* Gets a set with the names of the attributes of the wrapped node.
*
* @return the attribute names of this node
*/
Set getAttributes() {
return nodeHandler.getAttributes(node);
}
/**
* Gets a list with the children of the wrapped node, again wrapped into {@code NodeData} objects.
*
* @return a list with the children
*/
List> getChildren() {
return wrapInNodeData(nodeHandler.getChildren(node));
}
/**
* Gets 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
*/
List> getChildren(final String name) {
return wrapInNodeData(nodeHandler.getChildren(node, name));
}
/**
* 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
*/
boolean matchesConfigRootNode(final HierarchicalConfiguration config) {
return config.getNodeModel().getNodeHandler().getRootNode().equals(node);
}
/**
* Returns the name of the wrapped node.
*
* @return the node name
*/
String nodeName() {
return nodeHandler.nodeName(node);
}
/**
* Wraps the passed in list of nodes in {@code NodeData} objects.
*
* @param nodes the list with nodes
* @return the wrapped nodes
*/
List> wrapInNodeData(final List nodes) {
return nodes.stream().map(n -> new NodeData<>(n, nodeHandler)).collect(Collectors.toList());
}
}
/** 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";
/**
* 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(final HierarchicalConfiguration config) {
final NodeHandler handler = config.getNodeModel().getNodeHandler();
return new NodeData<>(handler.getRootNode(), handler);
}
/**
* Tests whether the constructor argument represented by the given configuration node is a bean declaration.
*
* @param nodeData the configuration node in question
* @return a flag whether this constructor argument is a bean declaration
*/
private static boolean isBeanDeclarationArgument(final NodeData nodeData) {
return !nodeData.getAttributes().contains(ATTR_BEAN_CLASS_NAME);
}
/** Stores the associated configuration. */
private final HierarchicalConfiguration configuration;
/** Stores the configuration node that contains the bean declaration. */
private final NodeData nodeData;
/** The name of the default bean class. */
private final String defaultBeanClassName;
/**
* Constructs 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(final HierarchicalConfiguration config, final NodeData node) {
this.nodeData = node;
configuration = config;
defaultBeanClassName = null;
initSubnodeConfiguration(config);
}
/**
* Constructs 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(final HierarchicalConfiguration config) {
this(config, (String) null);
}
/**
* Constructs 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(final HierarchicalConfiguration config, final String key) {
this(config, key, false);
}
/**
* Constructs 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(final HierarchicalConfiguration config, final String key, final boolean optional) {
this(config, key, optional, null);
}
/**
* Constructs 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(final HierarchicalConfiguration config, final String key, final boolean optional, final String defBeanClsName) {
if (config == null) {
throw new IllegalArgumentException("Configuration must not be null!");
}
HierarchicalConfiguration tmpconfiguration;
try {
tmpconfiguration = config.configurationAt(key);
} catch (final 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.nodeData = createNodeDataFromConfiguration(tmpconfiguration);
this.configuration = tmpconfiguration;
defaultBeanClassName = defBeanClsName;
initSubnodeConfiguration(getConfiguration());
}
/**
* 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 nodeData the child node, for which a {@code BeanDeclaration} is to be created
* @return the {@code BeanDeclaration} for this child node
*/
BeanDeclaration createBeanDeclaration(final NodeData nodeData) {
for (final HierarchicalConfiguration config : getConfiguration().configurationsAt(nodeData.escapedNodeName(getConfiguration()))) {
if (nodeData.matchesConfigRootNode(config)) {
return new XMLBeanDeclaration(config, nodeData);
}
}
throw new ConfigurationRuntimeException("Unable to match node for " + nodeData.nodeName());
}
/**
* Creates a {@code ConstructorArg} object for the specified configuration node.
*
* @param child the configuration node
* @return the corresponding {@code ConstructorArg} object
*/
private ConstructorArg createConstructorArg(final NodeData child) {
final String type = getAttribute(child, ATTR_CTOR_TYPE);
if (isBeanDeclarationArgument(child)) {
return ConstructorArg.forValue(getAttribute(child, ATTR_CTOR_VALUE), type);
}
return ConstructorArg.forBeanDeclaration(createBeanDeclaration(child), type);
}
/**
* Gets an attribute of a configuration node. This method also takes interpolation into account.
*
* @param nodeData the node
* @param attribute the name of the attribute
* @return the string value of this attribute (can be null)
*/
private String getAttribute(final NodeData nodeData, final String attribute) {
final Object value = nodeData.getAttribute(attribute);
return value == null ? null : String.valueOf(interpolate(value));
}
/**
* Gets 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();
}
/**
* Gets 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());
}
/**
* Gets 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);
}
/**
* Gets 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);
}
/**
* Gets 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() {
return getAttributeNames().stream().filter(e -> !isReservedAttributeName(e))
.collect(Collectors.toMap(Function.identity(), e -> interpolate(getNode().getAttribute(e))));
}
/**
* Gets the configuration object this bean declaration is based on.
*
* @return the associated configuration
*/
public HierarchicalConfiguration getConfiguration() {
return configuration;
}
/**
* {@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() {
return getNode().getChildren(ELEM_CTOR_ARG).stream().map(this::createConstructorArg).collect(Collectors.toCollection(LinkedList::new));
}
/**
* Gets 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;
}
/**
* Gets 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() {
final Map nested = new HashMap<>();
getNode().getChildren().forEach(child -> {
if (!isReservedChildName(child.nodeName())) {
final Object obj = nested.get(child.nodeName());
if (obj != null) {
final List list;
if (obj instanceof List) {
// Safe because we created the lists ourselves.
@SuppressWarnings("unchecked")
final 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;
}
/**
* Gets the data about the associated node.
*
* @return the node with the bean declaration
*/
NodeData getNode() {
return nodeData;
}
/**
* 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(final HierarchicalConfiguration conf) {
conf.setExpressionEngine(null);
}
/**
* 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(final Object value) {
final ConfigurationInterpolator interpolator = getConfiguration().getInterpolator();
return interpolator != null ? interpolator.interpolate(value) : value;
}
/**
* Tests 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(final String name) {
return isReservedName(name);
}
/**
* Tests 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(final String name) {
return isReservedName(name);
}
/**
* Tests 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(final String name) {
return name == null || name.startsWith(RESERVED_PREFIX);
}
}