MyBatis Example
Available as of Camel 2.12
This example is located in the examples/camel-example-mybatis directory of the Camel distribution.
There is a README.txt file with instructions how to run it.
If you use maven then you can easily install the example from the command line:
About
This example shows how to exchange data using a shared database table.
The example has two Camel routes. The first route insert new data into the table, triggered by a timer to run every 5th second.
The second route pickup the newly inserted rows from the table, process the row(s), and mark the row(s) as processed when done; to avoid picking up the same rows again.
Implementation
In the camel-mybatis.xml file in the src/main/resources/OSGI-INF/blueprint folder we have the Blueprint XML file. This example uses an embedded Database so we use the following bean to create and drop the table(s).
<bean id="initDatabase" class="org.apache.camel.example.mybatis.DatabaseBean"
init-method="create" destroy-method="destroy">
<property name="camelContext" ref="myBatisAndCamel"/>
</bean>
This example uses a bean to generate orders
<bean id="orderService" class="org.apache.camel.example.mybatis.OrderService"/>
And the CamelContext has two routes as shown below:
<camelContext id="myBatisAndCamel" xmlns="http://camel.apache.org/schema/blueprint">
<!-- route that generate new orders and insert them in the database -->
<route id="generateOrder-route">
<from uri="timer:foo?period=5s"/>
<transform>
<method ref="orderService" method="generateOrder"/>
</transform>
<to uri="mybatis:insertOrder?statementType=Insert"/>
<log message="Inserted new order ${body.id}"/>
</route>
<!-- route that process the orders by picking up new rows from the database
and when done processing then update the row to mark it as processed -->
<route id="processOrder-route">
<from uri="mybatis:selectOrders?statementType=SelectList&consumer._onConsume_=consumeOrder"/>
<to uri="bean:orderService?method=processOrder"/>
<log message="${body}"/>
</route>
</camelContext>
MyBatis SqlMapConfig.xml
MyBatis is configured using a SqlMapConfig.xml file located in the root of the classpath, eg in src/main/resources.
This configuration files setup MyBatis as well a pooled data source
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<setting name="useGeneratedKeys" value="false"/>
</settings>
<!-- Use type aliases to avoid typing the full classname every time. -->
<typeAliases>
<typeAlias alias="Order" type="org.apache.camel.example.mybatis.Order"/>
</typeAliases>
<!-- setup environment with JDBC data source -->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="org.apache.derby.jdbc.EmbeddedDriver"/>
<property name="url" value="jdbc:derby:memory:mybatis;create=true"/>
</dataSource>
</environment>
</environments>
<!-- mapping files -->
<mappers>
<mapper resource="org/apache/camel/example/mybatis/Order.xml"/>
</mappers>
</configuration>
MyBatis mapping files
MyBatis allows to externalize the SQL queries and mapping from SQL to POJOs.
We have a plain POJO org.apache.camel.example.mybatis.Order which just has getter/setters as shown below:
public class Order {
private int id;
private String item;
private int amount;
private String description;
private boolean processed;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getItem() {
return item;
}
public void setItem(String item) {
this.item = item;
}
public int getAmount() {
return amount;
}
public void setAmount(int amount) {
this.amount = amount;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public boolean isProcessed() {
return processed;
}
public void setProcessed(boolean processed) {
this.processed = processed;
}
}
And the MyBatis mapping file Order.xml is located in src/main/resources/org/apache/camel/example/mybatis where we map from SQL to this Order POJO, as shown below:
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="Order">
<!-- Result maps describe the mapping between the columns returned
from a query, and the class properties. A result map isn't
necessary if the columns (or aliases) match to the properties
exactly. -->
<resultMap id="OrderResult" type="Order">
<result property="id" column="ORD_ID"/>
<result property="item" column="ITEM"/>
<result property="amount" column="ITEM_COUNT"/>
<result property="description" column="ITEM_DESC"/>
<result property="processed" column="ORD_DELETED"/>
</resultMap>
<!-- Select with no parameters using the result map for Order class. -->
<select id="selectOrders" resultMap="OrderResult">
select * from ORDERS where ORD_DELETED = false order by ORD_ID
</select>
<!-- Insert example, using the Order parameter class -->
<insert id="insertOrder" parameterType="Order">
insert into ORDERS (
ORD_ID,
ITEM,
ITEM_COUNT,
ITEM_DESC,
ORD_DELETED
)
values (
#{id}, #{item}, #{amount}, #{description}, false
)
</insert>
<update id="consumeOrder" parameterType="Order">
update ORDERS set ORD_DELETED = true where ORD_ID = #{id}
</update>
</mapper>
Running the example
This example requires running in Apache Karaf / ServiceMix
To install Apache Camel in Karaf you type in the shell (we use version 2.12.0):
features:chooseurl camel 2.12.0
features:install camel
First you need to install the following features in Karaf/ServiceMix with:
features:install camel-mybatis
Then you can install the Camel example:
osgi:install -s mvn:org.apache.camel/camel-example-mybatis/2.12.0
And you can see the application running by tailing the logs
And you can use ctrl + c to stop tailing the log.
See Also
