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Ultimate JDBC Connection Pool
/*
* 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.util;
import java.io.IOException;
import java.lang.reflect.Array;
import java.sql.*;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import com.zaxxer.hikari.pool.*;
import javassist.*;
import javassist.bytecode.ClassFile;
/**
* 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 static ClassPool classPool;
private static String genDirectory = "";
public static void main(String... args) throws Exception {
classPool = new ClassPool();
classPool.importPackage("java.sql");
classPool.appendClassPath(new LoaderClassPath(JavassistProxyFactory.class.getClassLoader()));
if (args.length > 0) {
genDirectory = args[0];
}
// Cast is not needed for these
String methodBody = "{ try { return delegate.method($$); } catch (SQLException e) { throw checkException(e); } }";
generateProxyClass(Connection.class, ProxyConnection.class.getName(), methodBody);
generateProxyClass(Statement.class, ProxyStatement.class.getName(), methodBody);
generateProxyClass(ResultSet.class, ProxyResultSet.class.getName(), methodBody);
generateProxyClass(DatabaseMetaData.class, ProxyDatabaseMetaData.class.getName(), methodBody);
// For these we have to cast the delegate
methodBody = "{ try { return ((cast) delegate).method($$); } catch (SQLException e) { throw checkException(e); } }";
generateProxyClass(PreparedStatement.class, ProxyPreparedStatement.class.getName(), methodBody);
generateProxyClass(CallableStatement.class, ProxyCallableStatement.class.getName(), methodBody);
modifyProxyFactory();
}
private static void modifyProxyFactory() throws NotFoundException, CannotCompileException, IOException {
System.out.println("Generating method bodies for com.zaxxer.hikari.proxy.ProxyFactory");
String packageName = ProxyConnection.class.getPackage().getName();
CtClass proxyCt = classPool.getCtClass("com.zaxxer.hikari.pool.ProxyFactory");
for (CtMethod method : proxyCt.getMethods()) {
switch (method.getName()) {
case "getProxyConnection":
method.setBody("{return new " + packageName + ".HikariProxyConnection($$);}");
break;
case "getProxyStatement":
method.setBody("{return new " + packageName + ".HikariProxyStatement($$);}");
break;
case "getProxyPreparedStatement":
method.setBody("{return new " + packageName + ".HikariProxyPreparedStatement($$);}");
break;
case "getProxyCallableStatement":
method.setBody("{return new " + packageName + ".HikariProxyCallableStatement($$);}");
break;
case "getProxyResultSet":
method.setBody("{return new " + packageName + ".HikariProxyResultSet($$);}");
break;
case "getProxyDatabaseMetaData":
method.setBody("{return new " + packageName + ".HikariProxyDatabaseMetaData($$);}");
break;
default:
// unhandled method
break;
}
}
proxyCt.writeFile(genDirectory + "target/classes");
}
/**
* Generate Javassist Proxy Classes
*/
private static void generateProxyClass(Class primaryInterface, String superClassName, String methodBody) throws Exception
{
String newClassName = superClassName.replaceAll("(.+)\\.(\\w+)", "$1.Hikari$2");
CtClass superCt = classPool.getCtClass(superClassName);
CtClass targetCt = classPool.makeClass(newClassName, superCt);
targetCt.setModifiers(Modifier.setPublic(Modifier.FINAL));
System.out.println("Generating " + newClassName);
// Make a set of method signatures we inherit implementation for, so we don't generate delegates for these
Set superSigs = new HashSet<>();
for (CtMethod method : superCt.getMethods()) {
if ((method.getModifiers() & Modifier.FINAL) == Modifier.FINAL) {
superSigs.add(method.getName() + method.getSignature());
}
}
Set methods = new HashSet<>();
for (Class intf : getAllInterfaces(primaryInterface)) {
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 = superCt.getMethod(intfMethod.getName(), intfMethod.getSignature());
if ((superMethod.getModifiers() & Modifier.ABSTRACT) != Modifier.ABSTRACT && !isDefaultMethod(intf, intfMethod)) {
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);
}
}
targetCt.getClassFile().setMajorVersion(ClassFile.JAVA_8);
targetCt.writeFile(genDirectory + "target/classes");
}
private static boolean isThrowsSqlException(CtMethod method)
{
try {
for (CtClass clazz : method.getExceptionTypes()) {
if (clazz.getSimpleName().equals("SQLException")) {
return true;
}
}
}
catch (NotFoundException e) {
// fall thru
}
return false;
}
private static boolean isDefaultMethod(Class intf, CtMethod intfMethod) throws Exception
{
List> paramTypes = new ArrayList<>();
for (CtClass pt : intfMethod.getParameterTypes()) {
paramTypes.add(toJavaClass(pt));
}
return intf.getDeclaredMethod(intfMethod.getName(), paramTypes.toArray(new Class[0])).toString().contains("default ");
}
private static Set> getAllInterfaces(Class clazz)
{
Set> interfaces = new LinkedHashSet<>();
for (Class intf : clazz.getInterfaces()) {
if (intf.getInterfaces().length > 0) {
interfaces.addAll(getAllInterfaces(intf));
}
interfaces.add(intf);
}
if (clazz.getSuperclass() != null) {
interfaces.addAll(getAllInterfaces(clazz.getSuperclass()));
}
if (clazz.isInterface()) {
interfaces.add(clazz);
}
return interfaces;
}
private static Class toJavaClass(CtClass cls) throws Exception
{
if (cls.getName().endsWith("[]")) {
return Array.newInstance(toJavaClass(cls.getName().replace("[]", "")), 0).getClass();
}
else {
return toJavaClass(cls.getName());
}
}
private static Class toJavaClass(String cn) throws Exception
{
switch (cn) {
case "int":
return int.class;
case "long":
return long.class;
case "short":
return short.class;
case "byte":
return byte.class;
case "float":
return float.class;
case "double":
return double.class;
case "boolean":
return boolean.class;
case "char":
return char.class;
case "void":
return void.class;
default:
return Class.forName(cn);
}
}
}