Using Mybatis with Spring

Mybatis is Java Persistence framework, build upn JDBC. I look at it mostly as a bridge between conventional JDBC and an ORM solution like hibernate. The flexibility Mybatis provide is to write queries similar to JDBC, yet takes away all the complexity and boilerplate code for creating and maintaining connections and transactions. It can also map your objects to Tables like ORM solution, without getting into complexities of an ORM fraework, but at a cost of some additional code.

Mappers: Mappers are core of Mybatis implementation. A Mapper class would contain queries to be executed by mybatis. A good practice is to create a mapper for each table in database.

Here is a simple Mapper class

public interface UserMapper {

	/**
	 * This method validates the credentials for any user.
	 * 
	 * @param userName
	 * @param password
	 * @return
	 */
	@Select("select id from myuser where username=#{userName} and password=#{password}")
	public Integer verifyAdminUser(@Param("userName") String userName,
			@Param("password") String password);

	/**
	 * This method returns list of all users.
	 * 
	 * @return
	 */
	@Select("select username, password from myuser")
	public List getUsers();

In the getUsers method, you can see mybatis will automatically convert the results into a Java List with User objects.

Coming to Setting up Mybatis with Spring, if you are using Java based configuration, all you need to add is

@MapperScan("com.test.mapper")

and tell location of your mappers package(s).

In addition you would want spring to manage transactions for you by

@MapperScan("com.test.mapper")
public class MyConfig implements TransactionManagementConfigurer{

//JNDI lookup for database
private DataSource getDataSource() {
		InitialContext ic;
		DataSource ds = null;
		try {
			ic = new InitialContext();
			String jndiName ="jndi";
			ds = (DataSource) ic.lookup(jndiName);
		} 
		catch(Exception e)
		{
			e.printStackTrace();
		}
		return ds;
	}

	 @Bean
		public SqlSessionFactory sqlSessionFactory() throws Exception {
			org.apache.ibatis.mapping.Environment environment = new org.apache.ibatis.mapping.Environment("",
					new JdbcTransactionFactory(), getDataSource());
			org.apache.ibatis.session.Configuration config = new org.apache.ibatis.session.Configuration(environment);

			return new SqlSessionFactoryBuilder().build(config);
		}

	@Override
	public PlatformTransactionManager annotationDrivenTransactionManager() {
		return  new DataSourceTransactionManager(getDataSource());
	}

You are all set to use Mappers just by Autowiring in any class.

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