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Groovy: A powerful, dynamic language for the JVM
/**
* 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 groovy.sql;
import groovy.lang.GroovyObject;
import groovy.lang.GroovySystem;
import groovy.lang.MetaClass;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.ResultSet;
import org.codehaus.groovy.runtime.InvokerHelper;
/**
* GroovyResultSetProxy is used to create a proxy for GroovyResultSet.
* Due to the version incompatibility between java 6 and older versions
* methods with additional logic were moved into an extension class. When
* getting properties or calling methods, the runtime will try to first
* execute these on the extension and then on the ResultSet itself.
* This way it is possible to replace and add methods. To overload methods
* from ResultSet all methods have to be implemented on the extension
* class.
*
* @author Jochen Theodorou
*/
public final class GroovyResultSetProxy implements InvocationHandler {
private GroovyResultSetExtension extension;
/**
* Creates a new proxy instance.
* This will create the extension automatically using
* GroovyResultSetExtension
*
* @param set the result set to delegate to
* @see GroovyResultSetExtension
*/
public GroovyResultSetProxy(ResultSet set) {
extension = new GroovyResultSetExtension(set);
}
/**
* Creates a new proxy instance with a custom extension.
*
* @param ext the extension
* @see GroovyResultSetExtension
*/
public GroovyResultSetProxy(GroovyResultSetExtension ext) {
extension = ext;
}
/**
* Invokes a method for the GroovyResultSet.
* This will try to invoke the given method first on the extension
* and then on the result set given as proxy parameter.
*
* @param proxy the result set
* @param method the method name of this method will be used
* to make a call on the extension. If this fails the call will be
* done on the proxy instead
* @param args for the call
* @see ResultSet
* @see java.lang.reflect.InvocationHandler#invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[])
*/
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String name = method.getName();
if (method.getDeclaringClass() == GroovyObject.class) {
if (name.equals("getMetaClass")) {
return getMetaClass();
} else if (name.equals("setMetaClass")) {
return setMetaClass((MetaClass) args[0]);
}
}
return InvokerHelper.invokeMethod(extension, method.getName(), args);
}
private MetaClass metaClass;
private MetaClass setMetaClass(MetaClass mc) {
metaClass = mc;
return mc;
}
/**
* This class is introduced as a workaround for GROOVY-6187, which failed
* because if you use a metaclass from an interface, methods defined on
* Object cannot be called.
*/
private abstract static class DummyResultSet implements GroovyResultSet {}
private MetaClass getMetaClass() {
if (metaClass == null) {
metaClass = GroovySystem.getMetaClassRegistry().getMetaClass(DummyResultSet.class);
}
return metaClass;
}
/**
* Gets a proxy instance that can be used as GroovyResultSet.
*
* @return the proxy
*/
public GroovyResultSet getImpl() {
return (GroovyResultSet)
Proxy.newProxyInstance(
this.getClass().getClassLoader(),
new Class[]{GroovyResultSet.class},
this
);
}
}