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This GeoLatte-common library contains the transformer framework and other common classes used by other
GeoLatte modules.
/*
* This file is part of the GeoLatte project.
*
* GeoLatte is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GeoLatte is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with GeoLatte. If not, see
* - The method {@link EntityClassReader#getId(Object)} is identical to {@link EntityClassReader#getPropertyValue(Object, String)}
*
- The method {@link EntityClassReader#getGeometry(Object)} will return the value of the first field encountered that can be assigned to a geometry.
* If more than one of those fields are present, you will therefore get a random one! If no geometry fields exist, null
* will always be returned.
*
*
*
* Creation-Date: 9-apr-2010
* Creation-Time: 11:48:54
*
*
* @author Yves Vandewoude
* @author Bert Vanhooff
* @author Qmino bvba
* @since SDK1.5
*/
public class EntityClassReader {
private final static String DEFAULT_ID_PROPERTY = "id";
// Map with all readers, to avoid duplicate readers
private static Map> allReaders = new HashMap>();
// Map with all property getter names, except for the id and the geometry property
private Map accessorMap = new HashMap();
// Methods to access the geometry and id respectively
private Accessor geometryAccessor;
private Accessor idAccessor;
// Class mapped by this reader
private Class entityClass;
/*
* The declaredmethods of the feature-interface which is accessed by the proxy implementation
*/
private Method proxyIdGetMethod;
private Method proxyExistsMethod;
private Method proxyGeomGetMethod;
private Method proxyGeomNameGetMethod;
private Method proxyPropertiesGetMethod;
private Method proxyAttributeGetMethod;
private static String determineGeomProperty(Class entityClass) {
if (entityClass == null) return null;
for (Method method : getPropertyMethods(entityClass)){
if ( com.vividsolutions.jts.geom.Geometry.class.isAssignableFrom(method.getReturnType())
|| Geometry.class.isAssignableFrom(method.getReturnType())){
return propertyName(method);
}
}
return null;
}
/**
* Returns the property-accessors for the specified class;
*
* @param entityClass
* @return
*/
private static List getPropertyMethods(Class entityClass) {
List result = new ArrayList();
for (Method m : entityClass.getMethods()) {
if (m.getParameterTypes().length == 0 && m.getName().startsWith("get") && m.getReturnType() != void.class) {
if (m.getName().equals("getClass")) continue;
result.add(m);
}
}
return result;
}
/*
* Create a reader for a given entityclass which allows for easy access to properties of an object of an unknown
* class. Although any class can be given to the reader, the reader is made specifically for features.
*
* A feature has two special properties, which do not appear in the list of properties but
* are instead retrieved through a dedicated method: getGeometry() and getId(), the names of those properties
* are specified in this constructor. If for some reason, the given properties would not exist in the
* given class, or if the given property names are null, calling getId() or getGeometry() respectively
* will just return null. If the property that corresponds with the geometryPropertyName exists but corresponds with
* a non-geometry type, it is ignored and getGeometry() will return null. The property will, however, be added
* as a normal property.
*
* @param entityClass the class for which a reader is desired.
* @param geometryPropertyName the name of the property to map as the geometry. If null, no property will be mapped as the geometry property.
* @param idPropertyName the name of the property to use as the objectid. If null, no property will be mapped as the geometry property.
* @throws IllegalArgumentException if the given class is null
*/
private EntityClassReader(Class entityClass, String geometryPropertyName, String idPropertyName) {
if (entityClass == null) {
throw new IllegalArgumentException("Given entityclass may not be null");
}
this.entityClass = entityClass;
for (Method m : getPropertyMethods(entityClass)) {
String propertyName = propertyName(m);
boolean toAdd = true;
if (isPropertyGeometryProperty(geometryPropertyName, m, propertyName)) {
geometryAccessor = Accessor.newInstance(m, propertyName);
toAdd = false;
}
if (isPropertyIdProperty(idPropertyName, propertyName)) {
idAccessor = Accessor.newInstance(m, propertyName);
toAdd = false;
}
if (toAdd) {
accessorMap.put(propertyName, Accessor.newInstance(m, propertyName));
}
}
}
private boolean isPropertyIdProperty(String idPropertyName, String propertyName) {
if (idAccessor != null){
return false;
}
return idPropertyName != null && idPropertyName.equals(propertyName);
}
private boolean isPropertyGeometryProperty(String geometryPropertyName, Method method, String propertyName) {
if (geometryAccessor != null) {
return false;
}
boolean isGeometry = (com.vividsolutions.jts.geom.Geometry.class.isAssignableFrom(method.getReturnType()))
|| (Geometry.class.isAssignableFrom(method.getReturnType()));
return geometryPropertyName != null && isGeometry;
}
/**
* Factorymethod that returns the reader for a given entity class which allows for easy access to properties of an
* object of an unknown class. Although any class can be given to the reader, the reader is made specifically for features.
*
* A feature has two special properties, which do not appear in the list of properties but
* are instead retrieved through a dedicated method: getGeometry() and getId(). The reader retrieved by this method
* will consider the first property encountered with type geometry (or a subclass of geometry) to be the geometry,
* and the property with name "id" is considered the id. For a custom mapping of those properties, the alternative
* factory method should be used. If for some reason the property 'id' is of type geometry, and it is
* encountered as the first property of that type, it functions as both the id and the geometry of the feature.
*
* Presence of those properties is not required. If they are not present, calling getId() or getGeometry()
* will just return null.
*
* @param entityClass the class for which a reader is desired.
* @return the reader for the given class, which is unique. Subsequent calls to this with the same entityclass will
* return the same readerobject.
*/
public static synchronized EntityClassReader getClassReaderFor(Class entityClass) {
return getClassReaderFor(entityClass, determineGeomProperty(entityClass), DEFAULT_ID_PROPERTY);
}
/**
* Factorymethod that returns the reader for a given entity class which allows for easy access to properties of an
* object of an unknown class. Although any class can be given to the reader, the reader is made specifically for features.
*
* A feature has two special properties, which do not appear in the list of properties but
* are instead retrieved through a dedicated method: getGeometry() and getId(). The reader retrieved by this method
* allows the user to specify the name of the geometry and id property. If for some reason, the given properties
* would not exist in the given class, or if the given property names are null, calling getId() or getGeometry() respectively
* will just return null. If the property that corresponds with the geometryPropertyName exists but corresponds with
* a non-geometry type, it is ignored and getGeometry() will return null. The property will, however, be added
* as a normal property.
*
*
* @param entityClass the class for which a reader is desired.
* @param geometryPropertyName the name of the property representing the geometry of the feature
* @param idPropertyName the name of the property representing the id of the feature
* @return the reader for the given class, which is unique. Subsequent calls to this with the same entityclass and
* propertynames will return the same readerobject.
*/
public static synchronized EntityClassReader getClassReaderFor(Class entityClass, String geometryPropertyName, String idPropertyName) {
if (entityClass == null) {
return null;
}
String entryKey = "" + geometryPropertyName + "|" + idPropertyName;
Map readersForClass = allReaders.get(entityClass);
if (readersForClass == null) {
readersForClass = new HashMap();
allReaders.put(entityClass, readersForClass);
}
if (!readersForClass.containsKey(entryKey)) {
readersForClass.put(entryKey, new EntityClassReader(entityClass, geometryPropertyName, idPropertyName));
}
return readersForClass.get(entryKey);
}
/**
* Returns the name of the geometryfield of the given entity. If no geometry field exists, null is returned.
*
* @return the name of the geometryproperty, or null if no geometryproperty exists
*/
public String getGeometryName() {
String result = null;
if (geometryAccessor != null) {
result = geometryAccessor.getPropertyName();
}
return result;
}
/**
* Returns the name of the idfield of the given entity. If no id field exists, null is returned.
*
* @return the name of the idproperty, or null if no geometryproperty exists
*/
public String getIdName() {
String result = null;
if (idAccessor != null) {
result = idAccessor.getPropertyName();
}
return result;
}
/**
* Returns the value of the id of the given object if it is present. If no id property
* could be found, null is returned.
*
* @param objectToGet the object from which the id is desired.
* @return the value of the id property of the given object
* @throws IllegalStateException if no value can be retrieved from the object.
*/
public Object getId(Object objectToGet)
throws InvalidObjectReaderException {
if (objectToGet == null) {
throw new IllegalArgumentException("Given object may not be null");
}
if (objectToGet.getClass() != entityClass) {
throw new InvalidObjectReaderException("Class of target object does not correspond with entityclass of this reader.");
}
if (idAccessor == null) {
return null;
} else {
return idAccessor.getValueFrom(objectToGet);
}
}
/**
* Will retrieve the value of the geometryfield in the given object. If no geometryfield
* exists, null is returned. If more than one exist, a random one is returned.
*
* @param objectToGet the object from which the geometry is to be fetched.
* @return the geometry of the given object
* @throws InvalidObjectReaderException If the class of objectToGet does not correspond with the entityclass of this reader.
* @throws IllegalArgumentException the given object may not be null
*/
public Geometry getGeometry(Object objectToGet) throws InvalidObjectReaderException {
if (objectToGet == null) {
throw new IllegalArgumentException("The given object may not be null");
}
if (objectToGet.getClass() != entityClass) {
throw new InvalidObjectReaderException("Class of target object does not correspond with entityclass of this reader.");
}
if (geometryAccessor == null) {
return null;
} else {
return (Geometry) geometryAccessor.getValueFrom(objectToGet);
}
}
/**
* Returns the value of the property with a given name from the given object
*
* @param objectToGet The object from which the property value is to be retrieved
* @param propertyPath The dot-separated path of the property to retrieve. E.g. directly property: "name",
* sub property: "streetAddress.number"
* @return The value of the named property in the given object or null if the property can not
* be found
* @throws InvalidObjectReaderException If the class of the given object does not correspond with the entityclass
* of this reader
* @throws IllegalArgumentException if the given objectToGet or propertyValue is null
*/
public Object getPropertyValue(Object objectToGet, String propertyPath) throws InvalidObjectReaderException {
if (objectToGet == null || propertyPath == null) {
throw new IllegalArgumentException("Given object/propertyname may not be null");
}
if (objectToGet.getClass() != entityClass) {
throw new InvalidObjectReaderException("Class of target object does not correspond with entityclass of this reader.");
}
StringTokenizer tokenizer = new StringTokenizer(propertyPath, ".", false);
return getPropertyValue(objectToGet, tokenizer);
}
/**
* Recursive method to get the value of a property path.
*
* @param objectToGet The object from which the property value is to be retrieved.
* @param propertyPathParts A set of property names, with enumeration pointer pointed at the last handled part.
* @return The value of the named property in the given object or null if the property can not be found.
*/
private Object getPropertyValue(Object objectToGet, StringTokenizer propertyPathParts) {
String propertyName = propertyPathParts.nextToken();
Object propertyValue = null;
if (accessorMap.containsKey(propertyName)) {
propertyValue = accessorMap.get(propertyName).getValueFrom(objectToGet);
}
if (!propertyPathParts.hasMoreTokens() || propertyValue == null)
return propertyValue;
else {
EntityClassReader currentPathReader = EntityClassReader.getClassReaderFor(propertyValue.getClass());
return currentPathReader.getPropertyValue(propertyValue, propertyPathParts);
}
}
/**
* Retrieves the type of the given property path.
*
* @param propertyPath The dot-separated path of the property type to retrieve. E.g. directly property: "name",
* sub property: "streetAddress.number"
* @return the type of the property with the given name or null if the propertyName is not a property of the class managed
* by this reader.
* @throws IllegalArgumentException if propertyName is null.
*/
public Class getPropertyType(String propertyPath) {
if (propertyPath == null) {
throw new IllegalArgumentException("Propertyname may not be null");
}
StringTokenizer tokenizer = new StringTokenizer(propertyPath, ".", false);
return getPropertyType(tokenizer);
}
/**
* Recursive method to retrieve the type of the given property path.
*
* @param propertyPathParts A set of property names, with enumeration pointer pointed at the last handled part.
* @return The value of the named property in the given object or null if the property can not be found.
*/
private Class getPropertyType(StringTokenizer propertyPathParts) {
String propertyName = propertyPathParts.nextToken();
Class propertyType = null;
if (accessorMap.containsKey(propertyName)) {
propertyType = accessorMap.get(propertyName).getReturnType();
} else if (propertyName.equals(getIdName())) {
propertyType = idAccessor.getReturnType();
} else if (propertyName.equals(getGeometryName())) {
propertyType = geometryAccessor.getReturnType();
}
if (!propertyPathParts.hasMoreTokens() || propertyType == null)
return propertyType;
else {
EntityClassReader currentPathReader = EntityClassReader.getClassReaderFor(propertyType);
return currentPathReader.getPropertyType(propertyPathParts);
}
}
/**
*
* Parses a given string into an object whose class corresponds with the type of the property given. For example,
* if you give the method "4", and you ask it to parse like "width", and width is of the type Long, you will
* receive an object of the type Long. If the property of the underlying class has a primitive type as its type,
* the method will return the boxed variant instead.
*
*
* Currently, this method is only implemented for all numeric and boolean java types.
*
*
* @param stringToParse The string to convert into an object
* @param propertyPath Dot-separated path to the property whose type is to be used as the class to convert to
* @return A converted instance of the given string into the type of the given property. If the propertyName does
* not correspond with a property name, null is returned. If the propertyName has any other type than a supported type
* the original string is returned.
*/
public Object parseAsPropertyType(String stringToParse, String propertyPath) {
Class propertyType = getPropertyType(propertyPath);
if (propertyType == null) {
return null;
}
NumberTransformer parser = transformers.get(propertyType);
return parser == null ? stringToParse : parser.parseObject(stringToParse);
}
/**
* Returns whether a 'normal' property exists with a given name. A property a is said to exist
* if the underlying class contains a method A getA().
*
* The id and geometry of the feature are not considered as normal properties. Depending on the value of the second
* parameter, the method will return true or false if the given propertyname corresponds with the id or geometryfield
*
* @param propertyName the name of the property to check
* @param trueForSpecialProperties the answer to return if the given property corresponds with either the id or the
* geometry property of the feature
* @return whether a property with that name exists
* @throws IllegalArgumentException if the given propertyname is null
*/
public boolean exists(String propertyName, boolean trueForSpecialProperties) {
if (propertyName == null) {
throw new IllegalArgumentException("Given object may not be null");
}
boolean normalProperty = accessorMap.containsKey(propertyName);
return normalProperty || (trueForSpecialProperties &&
(getIdName() != null && getIdName().equals(propertyName) ||
getGeometryName() != null && getGeometryName().equals(propertyName)));
}
/**
* Get a list of all properties of the underlying class.
*
* @return the list of all properties of the given class.
*/
public Collection getProperties() {
return accessorMap.keySet();
}
/**
* Wraps the given object in a feature interface. This method will first validate whether the
* class it represents is indeed a feature (containing exactly one geometry and id) and will then
* generate a wrapper around the original object that obeys to the Feature interface.
* If this method is invoked multiple times on the same object, the same wrapper will be returned in
* each of these calls.
*
* @param objectToTransform the object for which a feature is desired.
* @return a feature wrapper around the given object
* @throws InvalidObjectReaderException If the class of objectToTransform does not correspond with the entityclass
* of this reader
* @throws IllegalArgumentException if the given objectToTransform is null
*/
public Feature asFeature(Object objectToTransform) throws InvalidObjectReaderException {
if (objectToTransform == null) {
throw new IllegalArgumentException("Given object may not be null");
}
if (proxyPropertiesGetMethod == null) {
Class[] emptyArray = new Class[]{};
try {
//This is not terribly threadsafe, and also inefficient. Should this not be moved to the constructor?
//TODO -- refactor
proxyGeomGetMethod = Feature.class.getDeclaredMethod("getGeometry", emptyArray);
proxyGeomNameGetMethod = Feature.class.getDeclaredMethod("getGeometryName", emptyArray);
proxyIdGetMethod = Feature.class.getDeclaredMethod("getId", emptyArray);
proxyExistsMethod = Feature.class.getDeclaredMethod("hasProperty", new Class[]{String.class, boolean.class});
proxyAttributeGetMethod = Feature.class.getDeclaredMethod("getProperty", new Class[]{String.class});
proxyPropertiesGetMethod = Feature.class.getDeclaredMethod("getProperties", emptyArray);
} catch (NoSuchMethodException e) {
// This can not happen, since we control the feature interface class. So this must be some version-
// error in the geolatte library!
throw new RuntimeException("Version mismatch: apparantly certain methods are not present in the Feature interface");
}
}
if (objectToTransform.getClass() != entityClass) {
throw new InvalidObjectReaderException("Class of target object does not correspond with entityclass of this reader.");
}
Feature proxy = (Feature) Proxy.newProxyInstance(entityClass.getClassLoader(),
new Class[]{Feature.class}, new ObjectInvocationHandler(objectToTransform));
return proxy;
}
private static String propertyName(Method m) {
return decapitalize(m.getName().substring(3));
}
/**
* Returns a string that is identical to the original string except that the fist character is now lowercase
* (regardless of how it was originally)
*
* @param inputString the string to capitalize
* @return a capitalized version of the string
*/
private static String decapitalize(String inputString) {
return inputString.length() > 1 ? Character.toLowerCase(inputString.charAt(0)) + inputString.substring(1)
: inputString.toUpperCase();
}
/**
* The objectinvocationhandler class is an internal class that implements the proxy interface of a feature
* by redirecting their calls to the creating entityclassreader.
*/
class ObjectInvocationHandler implements InvocationHandler {
private Object target;
ObjectInvocationHandler(Object targetObject) {
target = targetObject;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (proxyAttributeGetMethod.equals(method)) {
return EntityClassReader.this.getPropertyValue(target, (String) args[0]);
} else if (proxyIdGetMethod.equals(method)) {
return EntityClassReader.this.getId(target);
} else if (proxyGeomGetMethod.equals(method)) {
return EntityClassReader.this.getGeometry(target);
} else if (proxyGeomNameGetMethod.equals(method)) {
return EntityClassReader.this.getGeometryName();
} else if (proxyPropertiesGetMethod.equals(method)) {
return EntityClassReader.this.getProperties();
} else if (proxyExistsMethod.equals(method)) {
return EntityClassReader.this.exists((String) args[0], (Boolean) args[1]);
} else {
// This should not happen! I use a runtimeexception since we can not
// change the interface of the invoke method.
throw new RuntimeException("Unexisting method invoked on proxy.");
}
}
}
// Static objectconvertors.
private static Map transformers = new HashMap();
static {
transformers.put(Integer.class, new IntegerTransformer());
transformers.put(int.class, new IntegerTransformer());
transformers.put(Long.class, new LongTransformer());
transformers.put(long.class, new LongTransformer());
transformers.put(Double.class, new DoubleTransformer());
transformers.put(double.class, new DoubleTransformer());
transformers.put(Short.class, new ShortTransformer());
transformers.put(short.class, new ShortTransformer());
transformers.put(Float.class, new FloatTransformer());
transformers.put(float.class, new FloatTransformer());
transformers.put(Boolean.class, new BooleanTransformer());
transformers.put(boolean.class, new BooleanTransformer());
transformers.put(Byte.class, new ByteTransformer());
transformers.put(byte.class, new ByteTransformer());
transformers.put(BigDecimal.class, new BigDecimalTransformer());
}
private static interface NumberTransformer {
Object parseObject(String s);
}
private static class IntegerTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Integer.valueOf(s);
}
}
private static class BigDecimalTransformer implements NumberTransformer {
public Object parseObject(String s) {
return BigDecimal.valueOf(Double.valueOf(s));
}
}
private static class DoubleTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Double.valueOf(s);
}
}
private static class LongTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Long.valueOf(s);
}
}
private static class BooleanTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Boolean.valueOf(s);
}
}
private static class FloatTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Float.valueOf(s);
}
}
private static class ByteTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Byte.valueOf(s);
}
}
private static class ShortTransformer implements NumberTransformer {
public Object parseObject(String s) {
return Short.valueOf(s);
}
}
}
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