What is MyBatis?

MyBatis eliminates almost all of the JDBC code and manual setting of parameters and retrieval of results.
web.xml

sql-map-config.xml

For Spring Mybatis, there are 3 ways to retrieve the sessions
A. extend SqlSessionDaoSupport
Step 1. Create SqlSessionFactory bean in config file
Step 2. Extend your dao class with SqlSessionDAOSupport and use getSQLSession() which will return SqlSessionTemplate
B. Use SqlSessionTemplate
Step 1. Create template bean



Step 2. user getSqlSession() in dao
C. Using MapperFactoryBean
Step 1. Create DAO interfaces (CustomerMapperInterface.java)
Step 2. Create base mapper object (BaseMapperInterface is a marker interface.)




Step 3. Define object specific mapper



Step 4. Define CustomerMapper.xml

Your queries

Step 5. Use mapper in service implementation class
@Service
public class CustomerService implements CustomerBaseService{
@Autowired
CustomerMapperInterface custMapper;
@Override
public Customer getCustomerById(long empId){
//retrieve from database
Customer cust = custMapper.getCustomerWithId(custId);
return cust;
}
}
ResultMap
Describes how to load your objects from the database result sets.



typeHandler="com.aci.data.dao.mybatis.util.StringToBooleanTypeHandler" />




javaType="com.aci.model.Address">





javaType="com.aci.model.Address" resultMap="AddressSQL.addressMap" />
javaType="java.util.List" ofType="com.aci.data.Accounts" select="selectAccounts" />






resultType="java.util.List" resultMap="AccountsSQL.accountsMap"> SELECT Account_Id FROM Accounts WHERE cust_ID = #{custId}
Select/ Insert/ Update/ Delete statements syntax
Select Statement
parameterType=¡¨int¡¨ parameterMap=¡¨deprecated¡¨ resultType=¡¨hashmap¡¨ resultMap=¡¨personResultMap¡¨ flushCache=¡¨false¡¨ useCache=¡¨true¡¨ timeout=¡¨10000¡¨ fetchSize=¡¨256¡¨ statementType=¡¨PREPARED¡¨ resultSetType=¡¨FORWARD_ONLY¡¨> your query
Insert Statements
„h If your database supports auto-generated key fields (e.g. MySQL and SQL Server), then you can simply set useGeneratedKeys="true" and set the keyProperty to the target property

insert into Author (username,password,email,bio,isActive) values
(#{username},#{password},#{email},#{bio}, #{isActive, jdbcType=VARCHAR, typeHandler=com.wm.ping.data.dao.mybatis.util.StringToBooleanTypeHandler})

„h MyBatis has another way to deal with key generation for databases that don't support auto-generated column types,
id="insertAuthor"
parameterType="domain.blog.Author"
flushCache="true"
statementType="PREPARED"
keyProperty=""
keyColumn=""
useGeneratedKeys="false"
timeout="20000">

SELECT Author_SEQ.NEXTVAL FROM DUAL

your query

Update Statements
id="insertAuthor"
parameterType="domain.blog.Author"
flushCache="true"
statementType="PREPARED"
timeout="20000"> your query

Delete Statements
id="insertAuthor"
parameterType="domain.blog.Author"
flushCache="true"
statementType="PREPARED"
timeout="20000"> your query

Reusable SQL fragment
id,username,password

select from some_table where id = #{id}

Type Aliases



TypeHandler
public class StringToBooleanTypeHandler implements TypeHandler {
override getResult for ResultSet
override getResult for Callable statements
override setParameter for prepared statements
}
ResultHandlers
Allows you to handle each row as per your requirement.
Extend your class with ResultHandler and override method handleResult(ResultContext rc)
Cache
By default no caching except local session caching.
To enable 2nd level cache add following :

(Here I have added default values for properties, you can change it)
You can also implement custom cache by implementing Cache Interface given by mybatis
Dynamic SQL
¡E if statement

Add field / add where clause etc

¡E choose (when, otherwise)
For multiple if else conditions
¡E trim (where, set)
You can use with to dynamically add conditions

¡K

Also can use with to dynamically include columns to update statement


SELECT id, title, author FROM article WHERE id_category IN

#{category}