fdocuments.in_introduction-to-ibatis.ppt

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Introduction to iBatis
Kunal Umrigar

3
Problems
 Tight integration of SQL code and Java code.
 Redundant JDBC code consumes a lot of development time.
 Is our DAO really a DAO?

5
Hibernate (ORM)
Object-Relational Mapping
??

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Hibernate/Object-Relational Mapping
 Tools/techniques to store and retrieve objects from
a database
 From the code perspective it behaves like a
virtual object database
 A complete ORM solution provide:
 Basic CRUD functionality
 An Object-Oriented Query Facility
 Mapping Metadata support
 Transactional Capability

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Hibernate pros and cons
Pros:
 No SQL coding required
 Database vendor independent
 Provides caching mechanisms
Cons:
 Requires learning of quite a lot of stuff
 Limits queries to HQL syntax
 Debugging and performance tuning is sometimes quite
complected
 Does not fit with legacy or complex Database.

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An Introduction to Apache iBATIS
(i)nternet + A(batis)
SQL Mapping defined...

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About iBATIS
 Open source framework that reduces the complexity to
read/save Java objects from a database (persistence)
 Decouples Java code from SQL
 Avoids the necessity to use JDBC
 It is NOT an object-relational mapper (such as
Hibernate)
 Simplifies the developer’s life ☺

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iBatis Components
iBATIS usage is divided into two main components:
 SQLMaps
Permits to read/save Java objects into relational
DBMS without using JDBC and without mixing
Java and SQL code
 DAO <Spring framework DAO>
“Is an abstraction layer that hides the details of
your persistence solution and provides a common
API to the rest of your application”
Note: previous versions of iBatis had separate DAO component which is deprecated in the
latest version iBatis 3.

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Sql Mapping
SQL Mapping Maps objects to SQL statements
 NOT Classes to Tables
Fully functional SQL via named statements
 NOT generated SQL (although that’s possible)
For example...

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The Product Class
public class Product
{
private int id;
private String name;
private String description;
private BigDecimal cost;
private BigDecimal retail;
// ...getters/setters implied
}

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The SQL
<select id=“getProduct" parameterClass=“int”
resultClass="examples.domain.Product">
SELECT
PRODUCT_ID as id,
NAME,
DESCRIPTION,
COST,
RETAIL,
FROM PRODUCT
WHERE PRODUCT_ID = #id#
</select>

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<bean id="productDAO"
class="examples.domain.dao.ProductDAO">
<property name="sqlMapClient">
<ref bean="sqlMapClient" />
</property>
<property name="dataSource">
<ref bean="myDataSource" />
</property>
</bean>
The Spring DAO Bean

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public class ProductDAOImpl extends SqlMapClientDaoSupport
implements
ProductDao
{
@SuppressWarnings("unchecked")
public List<Product> getAllProducts(int id)
{
List<Product> productList =
getSqlMapClientTemplate().queryForList(
"getProduct" , id );
return productList;
}
.....
The Product DAO Implementation

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...
“WTF!! Do you mean we need to hand
code XML configurations?”
“Yeah!! That's true..”
...

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JDBC
 Obtain the db Connection
 Create the statement
 Set the input parameters
 Execute the statement
 Create the result Collection
 For each row fetched:
 Create an object
 Set object’s properties using
row’s colums
 Add the object to the
Collection
 Release resources
 Close the Connection
 Return the Collection
IBATIS
Obtain the SqlMap object
Prepare complex parameters
(optional)
Invoke the query passing the
parameters
Return the result
JDBC-iBatis Comparison

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5 Reasons to use iBatis
1. Works with any database that has a JDBC driver
(can re-use existing MySQL queries ) & You already
know SQL, why waste timelearning something else?
2. Supports Map, Collection, List and Primitive
Wrappers (Integer, String etc.)
3. Easy integration with Spring DAO.
4. Works well with legacy DB and complex relational
mappings between DB tables.
5. Supports complex object mappings (populating
lists, complex object models etc.), Transactions, Lazy
Loading or Join Mapping (1:1, 1:M, M:N), and caching.

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- Full power of real SQL
- Works with complex, enterprise, ERP or
even poorly designed databases
- Fully supports composite keys and
complex relationships
- Complete stored procedure support
- JavaBeans support
- Primitive wrappers (Integer, String,
Date etc.)
- HashMap, List, Collection, and array[]
- XML text and DOM Support
- Null value translation
- Auto-mapping bean properties to
columns
- Dynamic SQL using conditional XML
tags
- Caching and dependency management
- Centralized data source configuration
- Local and global (JTA) transaction
support
- Small footprint 300k (minimum)
- Minimal dependencies (only common-
logging required)
- Spring DAO Templates available
iBATIS SQL Mapping Framework

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Books:
 iBATIS In Action - Clinton Begin (Manning)
Links for reference:
 http://en.wikipedia.org/wiki/IBATIS
 http://ibatis.apache.org/onlinehelp.html
 http://www.javabeat.net/articles/52-spring-ibatis-integration-1.html
 http://www.learntechnology.net/content/ibatis/spring_ibatis.jsp
 Using-iBatis-SQL-Maps-for-Java-Data-Access

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