我可以在同一应用程序上下文中同时使用动态代理和CGLib代理吗？

Question

I'm building and End to End testing framework for a production spring batch project. We'd like to use an in-memory embedded db (in our case hsqldb) for these tests since it will run much faster and have not environmental constraints. Since the SQL syntax is slightly different between these db engines, we would like to use spring AOP to intercept the sql going to the database and take out/replace sql commands that are not supported. (we've looked at paramaterizing the sql completely, but we have the incompatible commands reduced to only a few little things, such as the "(nolock)" hint. )

I set up an AOP aspect for JDBCTemplate that works following a pretty standard aop pattern for logging sql:

@Pointcut("execution(* org.springframework.jdbc.core.JdbcOperations.*(String, ..))")
public void modifyJdbcOperations() {
}

and it works great with this spring config setup:

<aop:aspectj-autoproxy proxy-target-class="true" >
    <aop:include name = "SQLModifierAspect"/>
</aop:aspectj-autoproxy>

<aop:config proxy-target-class="true">
</aop:config>

<bean id="SQLModifierAspect" class="e2e.framework.SQLModifierAspect" />

Then I tried to set up a similar pointcut for the a method on one of our DAO objects that is constructor injected:

@Pointcut("execution(* com.*.dao.DateDao.buildSelectByDateCarryForward())")
public void modifyDateDao() {
}

But when I run the E2E framework with this pointcut I get:

Caused by: java.lang.IllegalArgumentException: Superclass has no null constructors but no arguments were given
at net.sf.cglib.proxy.Enhancer.emitConstructors(Enhancer.java:721) ~[cglib-2.2.jar:na]

I see that this is because I have configured to use CGLIB instead of Spring dynamic proxy based AOP. I read up on the differences here: http://docs.spring.io/spring/docs/3.0.0.M3/reference/html/ch08s06.html

I can't realistically refactor our entire production project to use property DI instead of constructor DI. If I switch back to Spring Dynamic Proxies, then the JdbcTemplate AOP doesn't work:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jdbcSupportBI' defined in class path resource [e2e-overrides.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type '$Proxy51 implementing org.springframework.jdbc.core.JdbcOperations,org.springframework.beans.factory.InitializingBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised' to required type 'org.springframework.jdbc.core.JdbcTemplate' for property 'jdbcTemplate';

So my question is: can I somehow configure aspectj to use Spring Dynamic Proxies for some classes, and CGLIB for others? Is there another way around this problem that only requires minimal refactoring?

Update: My current workaround is to have a SqlPreparer class that I inject into Daos as needed. I can make this have a default constructor. It adds an extra util class that doesn't do anything in production code, but it's not as invasive of a refactor:

/**
* Abstracted out of the GenericDao for AOP in the E2E tests
*/
public class SqlPreparer implements ISqlPreparer {

@Override
public String prepareSql(String sql) {
    return sql;
}
}

Answer 1

You could simply split your context into multiple contexts. One for your JdbcTemplate with aspects proxied through CGLIB and one for your DAO with aspects proxied through JDK proxies.

The error itself is because Spring seems to use the default CGLIB Enhancer behavior of proxying using the no-argument constructor of a class. Since your class doesn't have one, it fails. You could refactor your DataDao class and move constructor injection to field or setter injection and instead have a no-argument constructor.