/*
* Copyright (C) 2013, 2014 Brett Wooldridge
*
* Licensed 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 com.zaxxer.hikari.proxy;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.HashSet;
import java.util.Set;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.CtNewMethod;
import javassist.LoaderClassPath;
import javassist.Modifier;
import javassist.NotFoundException;
import com.zaxxer.hikari.util.ClassLoaderUtils;
/**
* This class generates the proxy objects for {@link Connection}, {@link Statement},
* {@link PreparedStatement}, and {@link CallableStatement}. Additionally it injects
* method bodies into the {@link ProxyFactory} class methods that can instantiate
* instances of the generated proxies.
*
* @author Brett Wooldridge
*/
public final class JavassistProxyFactory
{
private ClassPool classPool;
static {
ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
try {
Thread.currentThread().setContextClassLoader(JavassistProxyFactory.class.getClassLoader());
JavassistProxyFactory proxyFactoryFactory = new JavassistProxyFactory();
proxyFactoryFactory.modifyProxyFactory();
}
catch (Exception e) {
throw new RuntimeException("Fatal exception during proxy generation", e);
}
finally {
Thread.currentThread().setContextClassLoader(contextClassLoader);
}
}
/**
* Simply invoking this method causes the initialization of this class. All work
* by this class is performed in static initialization.
*/
public static void initialize()
{
// no-op
}
private JavassistProxyFactory() throws Exception
{
classPool = new ClassPool();
classPool.importPackage("java.sql");
classPool.appendClassPath(new LoaderClassPath(this.getClass().getClassLoader()));
// Connection is special, it has a checkClosed() call at the beginning
String methodBody = "{ checkClosed(); try { return delegate.method($$); } catch (SQLException e) { throw checkException(e); } }";
generateProxyClass(Connection.class, ConnectionProxy.class, methodBody);
// Cast is not needed for these
methodBody = "{ try { return delegate.method($$); } catch (SQLException e) { throw checkException(e); } }";
generateProxyClass(Statement.class, StatementProxy.class, methodBody);
generateProxyClass(ResultSet.class, ResultSetProxy.class, methodBody);
// For these we have to cast the delegate
methodBody = "{ try { return ((cast) delegate).method($$); } catch (SQLException e) { throw checkException(e); } }";
generateProxyClass(PreparedStatement.class, PreparedStatementProxy.class, methodBody);
generateProxyClass(CallableStatement.class, CallableStatementProxy.class, methodBody);
}
private void modifyProxyFactory() throws Exception
{
String packageName = JavassistProxyFactory.class.getPackage().getName();
CtClass proxyCt = classPool.getCtClass("com.zaxxer.hikari.proxy.ProxyFactory");
for (CtMethod method : proxyCt.getMethods()) {
switch (method.getName()) {
case "getProxyConnection":
method.setBody("{return new " + packageName + ".ConnectionJavassistProxy($$);}");
break;
case "getProxyStatement":
method.setBody("{return new " + packageName + ".StatementJavassistProxy($$);}");
break;
case "getProxyPreparedStatement":
method.setBody("{return new " + packageName + ".PreparedStatementJavassistProxy($$);}");
break;
case "getProxyCallableStatement":
method.setBody("{return new " + packageName + ".CallableStatementJavassistProxy($$);}");
break;
case "getProxyResultSet":
method.setBody("{return new " + packageName + ".ResultSetJavassistProxy($$);}");
break;
}
}
proxyCt.toClass(classPool.getClassLoader(), getClass().getProtectionDomain());
}
/**
* Generate Javassist Proxy Classes
*/
@SuppressWarnings("unchecked")
private <T> Class<T> generateProxyClass(Class<T> primaryInterface, Class<?> superClass, String methodBody) throws Exception
{
// Make a new class that extends one of the JavaProxy classes (ie. superClass); use the name to XxxJavassistProxy instead of XxxProxy
String superClassName = superClass.getName();
CtClass superClassCt = classPool.getCtClass(superClassName);
CtClass targetCt = classPool.makeClass(superClassName.replace("Proxy", "JavassistProxy"), superClassCt);
targetCt.setModifiers(Modifier.FINAL);
// Make a set of method signatures we inherit implementation for, so we don't generate delegates for these
Set<String> superSigs = new HashSet<String>();
for (CtMethod method : superClassCt.getMethods()) {
if ((method.getModifiers() & Modifier.FINAL) == Modifier.FINAL) {
superSigs.add(method.getName() + method.getSignature());
}
}
Set<String> methods = new HashSet<String>();
Set<Class<?>> interfaces = ClassLoaderUtils.getAllInterfaces(primaryInterface);
for (Class<?> intf : interfaces) {
CtClass intfCt = classPool.getCtClass(intf.getName());
targetCt.addInterface(intfCt);
for (CtMethod intfMethod : intfCt.getDeclaredMethods()) {
final String signature = intfMethod.getName() + intfMethod.getSignature();
// don't generate delegates for methods we override
if (superSigs.contains(signature)) {
continue;
}
// Ignore already added methods that come from other interfaces
if (methods.contains(signature)) {
continue;
}
// Track what methods we've added
methods.add(signature);
// Clone the method we want to inject into
CtMethod method = CtNewMethod.copy(intfMethod, targetCt, null);
String modifiedBody = methodBody;
// If the super-Proxy has concrete methods (non-abstract), transform the call into a simple super.method() call
CtMethod superMethod = superClassCt.getMethod(intfMethod.getName(), intfMethod.getSignature());
if ((superMethod.getModifiers() & Modifier.ABSTRACT) != Modifier.ABSTRACT) {
modifiedBody = modifiedBody.replace("((cast) ", "");
modifiedBody = modifiedBody.replace("delegate", "super");
modifiedBody = modifiedBody.replace("super)", "super");
}
modifiedBody = modifiedBody.replace("cast", primaryInterface.getName());
// Generate a method that simply invokes the same method on the delegate
if (isThrowsSqlException(intfMethod)) {
modifiedBody = modifiedBody.replace("method", method.getName());
}
else {
modifiedBody = "{ return ((cast) delegate).method($$); }".replace("method", method.getName()).replace("cast", primaryInterface.getName());
}
if (method.getReturnType() == CtClass.voidType) {
modifiedBody = modifiedBody.replace("return", "");
}
method.setBody(modifiedBody);
targetCt.addMethod(method);
}
}
return targetCt.toClass(classPool.getClassLoader(), getClass().getProtectionDomain());
}
private boolean isThrowsSqlException(CtMethod method)
{
try {
for (CtClass clazz : method.getExceptionTypes()) {
if (clazz.getSimpleName().equals("SQLException")) {
return true;
}
}
}
catch (NotFoundException e) {
// fall thru
}
return false;
}
}