MyBatis Custom TypeHandler Registration Without XML Configuration

To register a custom TypeHandler in MyBatis for a specific JDBC type and Java bean field type without referencing in XML files, you can follow the below steps:

1. Create a custom TypeHandler by implementing the TypeHandler interface. For example, if you want to map the JDBC type VARCHAR to a custom Java bean field type 'MyType', you can create a custom TypeHandler as follows:

public class MyTypeHandler implements TypeHandler<MyType> {
   @Override
   public void setParameter(PreparedStatement ps, int i, MyType parameter, JdbcType jdbcType) throws SQLException {
      ps.setString(i, parameter.toCustomString());
   }
   @Override
   public MyType getResult(ResultSet rs, String columnName) throws SQLException {
      return MyType.fromCustomString(rs.getString(columnName));
   }
   @Override
   public MyType getResult(ResultSet rs, int columnIndex) throws SQLException {
      return MyType.fromCustomString(rs.getString(columnIndex));
   }
   @Override
   public MyType getResult(CallableStatement cs, int columnIndex) throws SQLException {
      return MyType.fromCustomString(cs.getString(columnIndex));
   }
}

2. Register the custom TypeHandler with the MyBatis configuration. You can do this by creating a Configuration object and calling the registerTypeHandler() method on it. For example, if you want to register the above custom TypeHandler for the JDBC type VARCHAR and Java bean field type 'MyType', you can do it as follows:

Configuration configuration = new Configuration();
configuration.getTypeHandlerRegistry().register(MyType.class, JdbcType.VARCHAR, new MyTypeHandler());

3. Build the SqlSessionFactory using the Configuration object. You can do this as follows:

SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(configuration);

4. Use the SqlSessionFactory to create SqlSession and perform database operations as usual.

Note: If you are using MyBatis version 3.4.0 or later, you can also register the custom TypeHandler using annotations. To do this, you need to annotate the Java bean field with the '@TypeHandler' annotation and specify the custom TypeHandler class. For example, if you want to map the JDBC type VARCHAR to a custom Java bean field type 'MyType', you can annotate the Java bean field as follows:

public class MyBean {
   @TypeHandler(MyTypeHandler.class)
   private MyType myField;
   // ...
}

This will automatically register the custom TypeHandler for the JDBC type VARCHAR and Java bean field type 'MyType'.