About this Tutorial
This tutorial will show you two things:
- You don't need to write DAOs if you just need generic CRUD functionality.
- How to write DAOs when you need custom functionality.
If you're new to iBATIS, you might want to read the iBATIS Reference Guide before starting this tutorial.
Table of Contents
- Setup your project to use iBATIS
- Register a personDao bean definition
- Create a DAO Test to test finder functionality
- Create a DAO Interface and implementation
- Run the DAO Test
Setup your project to use iBATIS
To change a newly-created project to use iBATIS instead of Hibernate (the default), you'll need to perform the following steps:
- Change the <dao.framework> property in your pom.xml to be ibatis instead of hibernate.
- The *SQL.xml mapping files are currently MySQL-only, so if you want to use them with another database, you'll want to download them into your project and put them in a src/main/resources/sqlmaps directory. You can right-click, save as the following links: LookupSQL.xml
, RoleSQL.xml and UserSQL.xml.
- At this point, if you use JPA annotations on your POJOs, you can use the Hibernate3 Maven Plugin to generate your schema. To do this, change <implementation>annotationconfiguration</implementation> to <implementation>jpaconfiguration</implementation> in your pom.xml. If you'd like more control of your schema, see the instructions below.
- Delete src/main/resources/hibernate.cfg.xml. If you're using the sql-maven-plugin (step #2 below), you can delete the src/main/resources/META-INF directory from your project as well. If you want to use the AppFuse Maven Plugin to generate code, you will need to keep hibernate.cfg.xml in your project (at least for the M5 release).
Using SQL Maven Plugin to Generate Schema
- Download the schema creation DDL and put it in src/test/resources: MySQL or PostgreSQL.
- Remove the hibernate3-maven-plugin from your pom.xml and replace it with the sql-maven-plugin:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>sql-maven-plugin</artifactId>
<version>1.0</version>
<configuration>
<driver>${jdbc.driverClassName}</driver>
<username>${jdbc.username}</username>
<password>${jdbc.password}</password>
<url>${jdbc.url}</url>
<autocommit>true</autocommit>
<skip>${maven.test.skip}</skip>
</configuration>
<executions>
<execution>
<id>create-schema</id>
<phase>process-test-resources</phase>
<goals>
<goal>execute</goal>
</goals>
<configuration>
<autocommit>true</autocommit>
<srcFiles>
<srcFile>src/test/resources/${jdbc.groupId}-schema.sql</srcFile>
</srcFiles>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>${jdbc.groupId}</groupId>
<artifactId>${jdbc.artifactId}</artifactId>
<version>${jdbc.version}</version>
</dependency>
</dependencies>
</plugin>
 | Source Code
The code for this tutorial is located in the "tutorial-ibatis" module of the appfuse-demos project on Google Code. Use the following command to check it out from Subversion:
|
Register a personDao bean definition
AppFuse 2.x doesn't require you to write a DAO to persist a POJO. You can use one of the pre-existing classes if all you need is CRUD on an object:
- GenericDaoiBatis: A generics-based class that requires you to create a Spring bean definition.
- UniversalDaoiBatis: A class that requires you to cast to the specific object type.
The UniversalDaoiBatis class is already registered as a "dao" bean, so you can easily use it without any additional configuration. However, many developers prefer the generics-based DAO because it provides type safety. To register a personDao bean, open src/main/webapp/WEB-INF/applicationContext.xml (or core/src/main/resources/applicationContext.xml for a modular archetype) and add the following to it:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http:
xmlns:xsi="http:
xsi:schemaLocation="http: http:
<bean id="personDao" class="org.appfuse.dao.ibatis.GenericDaoiBatis">
<constructor-arg value="org.appfuse.tutorial.model.Person"/>
<property name="dataSource" ref="dataSource"/>
<property name="sqlMapClient" ref="sqlMapClient"/>
</bean>
</beans>
You will also need to create a PersonSQL.xml file in src/main/resources/sqlmaps:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sqlMap PUBLIC "-
"http:>
<sqlMap namespace="PersonSQL">
<typeAlias alias="person" type="org.appfuse.tutorial.model.Person"/>
<parameterMap id="addParam" class="person">
<parameter property="firstName" jdbcType="VARCHAR" javaType="java.lang.String"/>
<parameter property="lastName" jdbcType="VARCHAR" javaType="java.lang.String"/>
</parameterMap>
<parameterMap id="updateParam" class="person">
<parameter property="id" jdbcType="INTEGER" javaType="java.lang.Long"/>
<parameter property="firstName" jdbcType="VARCHAR" javaType="java.lang.String"/>
<parameter property="lastName" jdbcType="VARCHAR" javaType="java.lang.String"/>
</parameterMap>
<resultMap id="personResult" class="person">
<result property="id" column="id"/>
<result property="firstName" column="first_name"/>
<result property="lastName" column="last_name"/>
</resultMap>
<select id="getPersons" resultMap="personResult">
<![CDATA[
select * from person
]]>
</select>
<select id="getPerson" resultMap="personResult">
<![CDATA[
select * from person where id = #value#
]]>
</select>
<insert id="addPerson" parameterMap="addParam">
<![CDATA[
insert into person (first_name,last_name) values ( ?,? )
]]>
<selectKey resultClass="java.lang.Long" keyProperty="id" type="post">
SELECT LAST_INSERT_ID() AS id
</selectKey>
</insert>
<update id="updatePerson" parameterMap="updateParam">
<![CDATA[
update person set first_name = ?, last_name = ? where id = ?
]]>
</update>
<delete id="deletePerson">
<![CDATA[
delete from person where id = #value#
]]>
</delete>
</sqlMap>
Next, add a reference to the new SQL Map in src/main/resources/sql-map-config.xml:
<sqlMap resource="sqlmaps/PersonSQL.xml"/>
If you're using the sql-maven-plugin, you'll also need to add a "create table" statement to src/test/resources/mysql-schema.sql:
drop table if exists person;
CREATE TABLE person (
id int(8) auto_increment,
first_name varchar(50) NOT NULL,
last_name varchar(50) NOT NULL,
PRIMARY KEY (id)
);
After doing this, you can use this bean on an object by adding the following setter method:
public void setPersonDao(GenericDao<Person, Long> personDao) {
this.personDao = personDao;
}
If you need more than just CRUD functionality, you'll want to continue reading below. If not, you can continue to Creating new Managers. This is a tutorial for creating Business Facades, which are similar to Session Facades, but don't use EJBs. These facades are used to provide communication from the front-end to the DAO layer.
Create a DAO Test to test finder functionality
Now you'll create a DaoTest to test that your DAO works. "Wait a minute," you say, "I haven't created a DAO!" You are correct. However, I've found that Test-Driven Development breeds higher quality software. For years, I thought write your test before your class was hogwash. It just seemed stupid. Then I tried it and I found that it works great. The only reason I do test-driven stuff now is because I've found it rapidly speeds up the process of software development.
To start, create a PersonDaoTest.java class in your src/test/java/**/dao directory (or core/src/test/java/**/dao directory for a modular archetype). This class should extend org.appfuse.dao.BaseDaoTestCase, a subclass of Spring's AbstractTransactionalDataSourceSpringContextTests. This parent class is used to load Spring's ApplicationContext (since Spring binds interfaces to implementations), and for (optionally) loading a .properties file that has the same name as your *Test.class. In this example, if you put a PersonDaoTest.properties file in src/test/resources/org/appfuse/tutorial/dao, this file's properties will be available via an "rb" variable.
package org.appfuse.tutorial.dao;
import java.util.List;
import org.appfuse.dao.BaseDaoTestCase;
import org.appfuse.tutorial.model.Person;
import org.springframework.dao.DataAccessException;
public class PersonDaoTest extends BaseDaoTestCase {
private PersonDao personDao = null;
public void setPersonDao(PersonDao personDao) {
this.personDao = personDao;
}
}
The code you see above is what you need for a basic Spring integration test that initializes and configures an implementation of PersonDao. Spring will use autowiring by name to call the setPersonDao() method and set the "personDao" bean as a dependency of this class.
Now you need test that the finder method works in your DAO. To do this, create a method that begin with "test" (all lower case). As long as this method is public, has a void return type and take no arguments, it invoked and run by JUnit. Add the following method to your PersonDaoTest.java file:
public void testFindPersonByLastName() throws Exception {
List<Person> people = personDao.findByLastName("Raible");
assertTrue(people.size() > 0);
}
You'll notice that this method relies on pre-existing data in order to pass. The DbUnit Maven Plugin is used to populate the database with test data before the tests are run, so you can simply add the new table/record to the src/test/resources/sample-data.xml file (or core/src/test/resources/sample-data.xml for a modular archetype).
<table name='person'>
<column>id</column>
<column>first_name</column>
<column>last_name</column>
<row>
<value>1</value>
<value>Matt</value>
<value>Raible</value>
</row>
</table>
Since the PersonDao you're about to write includes CRUD functionality, you can also write a test to verify CRUD works properly.
public void testAddAndRemovePerson() throws Exception {
Person person = new Person();
person.setFirstName("Country");
person.setLastName("Bry");
personDao.save(person);
person = personDao.get(person.getId());
assertEquals("Country", person.getFirstName());
assertNotNull(person.getId());
log.debug("removing person...");
personDao.remove(person.getId());
try {
personDao.get(person.getId());
fail("Person found in database");
} catch (DataAccessException dae) {
log.debug("Expected exception: " + dae.getMessage());
assertNotNull(dae);
}
}
In the above example, you can see that person.set*(value) is being called to populate the Person object before saving it. This is easy in this example, but it could get quite cumbersome if you're persisting an object with 10 required fields. This is why a ResourceBundle exists in BaseDaoTestCase. Simply create a PersonDaoTest.properties file in the same directory as PersonDaoTest.java and define your property values inside it:
firstName=Matt
lastName=Raible
 |
I tend to just hard-code test values into Java code - but the .properties file is an option that works great for large objects. |
Then, rather than calling person.set* to populate your objects, you can use the BaseDaoTestCase.populate(java.lang.Object) method:
Person person = new Person();
person = (Person) populate(person);
At this point, the PersonDaoTest class won't compile yet because there is no PersonDao.class in your classpath, you need to create it.
Create a DAO Interface and implementation
Create a PersonDao.java interface in the src/main/java/**/dao (or core/src/main/java/**/dao for a modular archetype) directory and specify the finder method for any implementation classes.
package org.appfuse.tutorial.dao;
import org.appfuse.dao.GenericDao;
import org.appfuse.tutorial.model.Person;
import java.util.List;
public interface PersonDao extends GenericDao<Person, Long> {
public List<Person> findByLastName(String lastName);
}
Notice in the class above there is no exception on the method signature. This is due to the power of Spring and how it wraps Exceptions with RuntimeExceptions. At this point, you should be able to compile all your code using your IDE or mvn test-compile. However, if you try to run mvn test -Dtest=PersonDaoTest, you will get an error:
Running org.appfuse.tutorial.dao.PersonDaoTest
INFO - AbstractSingleSpringContextTests.loadContextLocations(179) | Loading context for: classpath*:/applicationContext-*.xml
Tests run: 2, Failures: 0, Errors: 2, Skipped: 0, Time elapsed: 0.449 sec <<< FAILURE!
Unfortunately, this doesn't tell you much about what went wrong. To find the real problem, you need to open target/surefire-reports/org.appfuse.tutorial.dao.PersonDaoTest.txt (or core/target/surefire-reports/org.appfuse.tutorial.dao.PersonDaoTest.txt for a modular archetype). In this file, the real problem is shown:
-------------------------------------------------------------------------------
Test set: org.appfuse.tutorial.dao.PersonDaoTest
-------------------------------------------------------------------------------
Tests run: 2, Failures: 0, Errors: 2, Skipped: 0, Time elapsed: 0.444 sec <<< FAILURE!
testFindPersonByLastName(org.appfuse.tutorial.dao.PersonDaoTest) Time elapsed: 0.401 sec <<< ERROR!
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean
with name 'org.appfuse.tutorial.dao.PersonDaoTest': Unsatisfied dependency expressed
through bean property 'personDao': Set this property value or disable dependency
checking for this bean.
| Showing errors in your console
To show testing errors in your console, append -Dsurefire.useFile=false to your mvn test command. |
This is an error message from Spring - indicating that you need to specify a bean named "personDao" in a Spring context file. Before you do that, you need to create the PersonDao implementation.
Create a PersonDaoiBatis class that implements the finder method in PersonDao. To do this, create a new class in src/main/java/**/dao/hibernate (or core/src/main/java/**/dao/hibernate for the modular archetype) and name it PersonDaoHibernate.java. It should extend GenericDaoiBatis and implement PersonDao. Javadocs eliminated for brevity.
package org.appfuse.tutorial.dao.ibatis;
import org.appfuse.tutorial.dao.PersonDao;
import org.appfuse.tutorial.model.Person;
import org.appfuse.dao.ibatis.GenericDaoiBatis;
import java.util.List;
public class PersonDaoiBatis extends GenericDaoiBatis<Person, Long> implements PersonDao {
public PersonDaoiBatis() {
super(Person.class);
}
@SuppressWarnings("unchecked")
public List<Person> findByLastName(String lastName) {
return (List<Person>) getSqlMapClientTemplate().queryForList("findByLastName", lastName);
}
}
You'll also need to add the findByLastName query to your PersonSQL.xml:
<select id="findByLastName" resultMap="personResult">
select * from person where last_name = #value#
</select>
Now, if you try to run mvn test -Dtest=PersonDaoTest, you will get the same error. You need to configure Spring so it knows that PersonDaoiBatis is the implementation of PersonDao.
Create an applicationContext.xml file in src/main/webapp/WEB-INF (or core/src/main/resources for a modular archetype) and add the following XML to it:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http:
xmlns:xsi="http:
xsi:schemaLocation="http: http:
<bean id="personDao" class="org.appfuse.tutorial.dao.ibatis.PersonDaoiBatis">
<property name="dataSource" ref="dataSource"/>
<property name="sqlMapClient" ref="sqlMapClient"/>
</bean>
</beans>
Run the DAO Test
Save all your edited files and try running mvn test -Dtest=PersonDaoTest one more time.
Yeah Baby, Yeah:
BUILD SUCCESSFUL
Total time: 9 seconds
*Incidentally, you can try running the tests from your IDE. Make sure you regenerate your project files after changing the pom dependencies. (run mvn idea:idea after any changes to dependencies. This is necessary in Idea though I'm not sure about Eclipse.)
Next Up: Part II: Creating new Managers - A HowTo for creating Business Facades, which are similar to Session Facades, but don't use EJBs. These facades are used to provide communication from the front-end to the DAO layer.
This page
Other pages
Account
