IndexedType.java
/*
* 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.jexl3.internal.introspection;
import java.beans.IntrospectionException;
import java.lang.reflect.Method;
import org.apache.commons.jexl3.introspection.JexlPropertyGet;
/**
* Abstract an indexed property container.
* <p>This allows getting properties from expressions like <code>var.container.property</code>.
* This stores the container name and class as well as the list of available getter and setter methods.
* It implements JexlPropertyGet since such a container can only be accessed from its owning instance (not set).
*/
public final class IndexedType implements JexlPropertyGet {
/**
* A generic indexed property container, exposes get(key) and set(key, value)
* and solves method call dynamically based on arguments.
* <p>Must remain public for introspection purpose.</p>
*/
public static final class IndexedContainer {
/** The container instance. */
final Object container;
/** The container type instance. */
final IndexedType type;
/**
* Creates a new duck container.
* @param theType the container type
* @param theContainer the container instance
*/
IndexedContainer(final IndexedType theType, final Object theContainer) {
this.type = theType;
this.container = theContainer;
}
/**
* Gets a property from this indexed container.
* @param key the property key
* @return the property value
* @throws Exception if inner invocation fails
*/
public Object get(final Object key) throws Exception {
return type.invokeGet(container, key);
}
/**
* Gets the property container class.
* @return the container class
*/
public Class<?> getContainerClass() {
return type.clazz;
}
/**
* Gets the property container name.
* @return the container name
*/
public String getContainerName() {
return type.container;
}
/**
* Sets a property in this indexed container.
* @param key the property key
* @param value the property value
* @return the invocation result (frequently null)
* @throws Exception if inner invocation fails
*/
public Object set(final Object key, final Object value) throws Exception {
return type.invokeSet(container, key, value);
}
}
/**
* Attempts to find an indexed-property getter in an object.
* The code attempts to find the list of methods getXXX() and setXXX().
* Note that this is not equivalent to the strict bean definition of indexed properties; the type of the key
* is not necessarily an int and the set/get arrays are not resolved.
*
* @param is the introspector
* @param object the object
* @param name the container name
* @return a JexlPropertyGet is successful, null otherwise
*/
public static JexlPropertyGet discover(final Introspector is, final Object object, final String name) {
if (object != null && name != null && !name.isEmpty()) {
final String base = name.substring(0, 1).toUpperCase() + name.substring(1);
final String container = name;
final Class<?> clazz = object.getClass();
final Method[] getters = is.getMethods(object.getClass(), "get" + base);
final Method[] setters = is.getMethods(object.getClass(), "set" + base);
if (getters != null) {
return new IndexedType(container, clazz, getters, setters);
}
}
return null;
}
/** The container name. */
final String container;
/** The container class. */
final Class<?> clazz;
/** The array of getter methods. */
private final Method[] getters;
/** Last get method used. */
private volatile Method get;
/** The array of setter methods. */
private final Method[] setters;
/** Last set method used. */
private volatile Method set;
/**
* Creates a new indexed property container type.
* @param name the container name
* @param c the owning class
* @param gets the array of getter methods
* @param sets the array of setter methods
*/
private IndexedType(final String name, final Class<?> c, final Method[] gets, final Method[] sets) {
this.container = name;
this.clazz = c;
this.getters = gets;
this.setters = sets;
}
@Override
public Object invoke(final Object obj) throws Exception {
if (obj != null && clazz.equals(obj.getClass())) {
return new IndexedContainer(this, obj);
}
throw new IntrospectionException("property resolution error");
}
/**
* Gets the value of a property from a container.
* @param object the container instance (not null)
* @param key the property key (not null)
* @return the property value
* @throws Exception if invocation failed;
* IntrospectionException if a property getter could not be found
*/
Object invokeGet(final Object object, final Object key) throws Exception {
if (getters != null && getters.length > 0) {
Method jm = get;
if (jm != null) {
final Class<?>[] ptypes = jm.getParameterTypes();
if (ptypes[0].isAssignableFrom(key.getClass())) {
return jm.invoke(object, key);
}
}
final Object[] args = {key};
final String methodName = getters[0].getName();
final MethodKey km = new MethodKey(methodName, args);
jm = km.getMostSpecificMethod(getters);
if (jm != null) {
final Object invoked = jm.invoke(object, args);
get = jm;
return invoked;
}
}
throw new IntrospectionException("property get error: "
+ object.getClass().toString()
+ "@" + key.toString());
}
/**
* Sets the value of a property in a container.
* @param object the container instance (not null)
* @param key the property key (not null)
* @param value the property value (not null)
* @return the result of the method invocation (frequently null)
* @throws Exception if invocation failed;
* IntrospectionException if a property setter could not be found
*/
Object invokeSet(final Object object, final Object key, final Object value) throws Exception {
if (setters != null && setters.length > 0) {
Method jm = set;
if (jm != null) {
final Class<?>[] ptypes = jm.getParameterTypes();
if (ptypes[0].isAssignableFrom(key.getClass())
&& (value == null
|| ptypes[1].isAssignableFrom(value.getClass()))) {
return jm.invoke(object, key, value);
}
}
final Object[] args = {key, value};
final String methodName = setters[0].getName();
final MethodKey km = new MethodKey(methodName, args);
jm = km.getMostSpecificMethod(setters);
if (jm != null) {
final Object invoked = jm.invoke(object, args);
set = jm;
return invoked;
}
}
throw new IntrospectionException("property set error: "
+ object.getClass().toString()
+ "@" + key.toString());
}
@Override
public boolean isCacheable() {
return true;
}
@Override
public boolean tryFailed(final Object rval) {
return rval == Uberspect.TRY_FAILED;
}
@Override
public Object tryInvoke(final Object obj, final Object key) {
if (obj != null && key != null
&& clazz.equals(obj.getClass())
&& container.equals(key.toString())) {
return new IndexedContainer(this, obj);
}
return Uberspect.TRY_FAILED;
}
}