1. Powerful persistence layer
with
Google Guice & MyBatis
GuiceCon, March 19th, 2011
Simone Tripodi
simonetripodi@apache.org
http://people.apache.org/~simonetripodi

2. MyBatis?!?

3. It reminds Apache iBATIS!
Indeed, MyBatis is the Apache iBATIS fork!
● Fork happened on 2010;
● The whole original team moved the project on
Google Code;
● Apache iBATIS moved to Attic and no more
maintained;
● New extensions after left ASF.

5. The Guice integration early days...
● Announced as independent project on Google
Code on December 2009 with iBaGuice name;
● Only 2 folks behind it: Simone Tripodi & Marco
Speranza;
● Focused on providing a smart iBATIS bootstrap and
related component injection.

6. ... and the merge with MyBatis
● Donated to MyBatis after the iBATIS fork;
● Community supported;
● Same objectives, better APIs;
● More 3
rd
parties integration:
● Apache Commons DBCP;
● Bone CP;
● C3P0;
● Built-in MyBatis DataSource.

7. MyBatis Confguration & Bootstrap
createInjector(new MyBatisModule() {
@Override
protected void initialize() {
environmentId("test");
bindDataSourceProviderType(PooledDataSourceProvider.class);
bindTransactionFactoryType(JdbcTransactionFactory.class);
addMapperClass(ContactMapper.class);
handleType(CustomType.class).with(CustomLongTypeHandler.class);
handleType(Address.class).with(AddressTypeHandler.class);
addInterceptorClass(CountUpdateInterceptor.class);
}
});

8. MyBatis XML Confguration
& Bootstrap
createInjector(new XMLMyBatisModule() {
@Override
protected void initialize() {
setEnvironmentId("test");
setClassPathResource("org/acme/mybatis-config.xml");
}
});

9. Require Mappers injection
public interface ContactMapper {
void brokenAdd(Contact contact);
void add(Contact contact);
void update(Contact contact);
void delete(Integer id);
Contact getById(Integer id);
List<Contact> selectAll();
}
@javax.inject.Singleton
public class ContactMapperClient {
@javax.inject.Inject
private ContactMapper contactMapper;
public void setContactMapper(ContactMapper contactMapper) {
this.contactMapper = contactMapper;
}
}

10. rd
3 parties DataSource
createInjector(new XMLMyBatisModule() {
@Override
protected void initialize() {
// MyBatis built-in
bindDataSourceProviderType(UnpooledDataSourceProvider.class);
bindDataSourceProviderType(PooledDataSourceProvider.class);
bindDataSourceProviderType(JndiDataSourceProvider.class);
// c3p0
bindDataSourceProviderType(C3p0DataSourceProvider.class);
// apache commons-dbcp
bindDataSourceProviderType(BasicDataSourceProvider.class);
bindDataSourceProviderType(SharedPoolDataSourceProvider.class);
bindDataSourceProviderType(PerUserPoolDataSourceProvider.class);
// BoneCP
bindDataSourceProviderType(BoneCPProvider.class);
}
});

11. Issue: boring transactions!
public class FooDao {
@Inject
private SqlSessionManager sessionManager;
public void setSessionManager(SqlSessionManager sessionManager) {
this.sessionManager = sessionManager;
}
public void doFooBar() throws MyDaoException {
this.sessionManager.startManagedSession(ExecutorType.BATCH,
TransactionIsolationLevel.READ_UNCOMMITTED);
try {
FooMapper fooMapper = this.sessionManager.getMapper(FooMapper.class);
fooMapper.doFoo();
BarMapper barMapper = this.sessionManager.getMapper(BarMapper.class);
barMapper.doBar();
this.sessionManager.commit();
} catch (Throwable t) {
this.sessionManager.rollback();
throw new MyDaoException("Something went wrong", t);
} finally {
this.sessionManager.close();
}
}

12. Solution: @Transactional
public class FooDao {
@Inject
private FooMapper fooMapper;
@Inject
private BarMapper barMapper;
// let's assume setters here
@Transactional(executorType = ExecutorType.BATCH,
isolationLevel = TransactionIsolationLevel.READ_UNCOMMITTED,
rethrowExceptionsAs = MyDaoException.class,
exceptionMessage = "Something went wrong")
public void doFooBar() {
this.fooMapper.doFoo();
this.barMapper.doBar();
}
}

13. JDBC Helper
Small issue: remember JDBC URL patterns and driver
class names
● Create index/catalog? :(
● Create automatic index/catalog! :)

14. JDBCHelper in action
● Just a module that automatically injects JDBC.url and
JDBC.driver properties used by DataSource providers;
● JDBC.url is a template;
● Pattern contains variables in ${name|defaultValue} format;
● Patterns require other properties, i.e.:
jdbc:mysql://${JDBC.host|localhost}:${JDBC.port|3306}/${JDBC.schema}
● Sample?
createInjector(JdbcHelper.MySQL, ...);

15. References
MyBatis home page: http://mybatis.org/
Google-Guice integration module:
http://code.google.com/p/mybatis/downloads/list?can=3&q=Product%3DGuice
Google-Guice integration SVN:
http://mybatis.googlecode.com/svn/sub-projects/mybatis-guice/trunk/

16. G R A Z I E :)