This document discusses integrating MyBatis, an object-relational mapping tool, with Google Guice for dependency injection. It describes how MyBatis is a fork of Apache iBATIS and the history of the Guice integration project. It also covers how to configure MyBatis using Guice modules, inject mappers, handle transactions with annotations, support various data sources, and provide JDBC helpers.

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 :)