iBATIS data access objects - iBATIS in Action - page 222

Listing 10.2 A simple example of using a DAO

package org.apache.mapper2.examples.chapter10.dao;

import com.ibatis.dao.client.DaoManager;
import com.ibatis.dao.client.DaoManagerBuilder;
import com.ibatis.common.resources.Resources;
import java.io.Reader;
import java.io.IOException;

public class DaoService {
private static DaoManager daoManager;

public static synchronized DaoManager getDaoManager(){
String daoXmlResource = "dao.xml";
Reader reader;
if (null == daoManager){
try {
reader =
Resources.getResourceAsReader(daoXmlResource);
daoManager =
DaoManagerBuilder.buildDaoManager(reader);
return daoManager;
} catch (IOException e) {
throw new RuntimeException(
"Unable to create DAO manager.", e);
}
} else {
return daoManager;
}
}

Specifies location
of config file

B

C

Gets a reader for
the builder

Builds DAO
manager

D

public static Dao getDao(Class interfaceClass){
return getDaoManager().getDao(interfaceClass);
}
}

We will look briefly at this listing, because it does have some bits of code that will
prove relevant later. The first in order of importance is the daoXmlResource vari-
able , which contains the location of the dao.xml file we saw in listing 10.1 ear-
lier. That is important because it is not a path, but rather a resource location on
the classpath. For example, if you are working on a web application, it would be in
the WEB-INF/classes directory. The Resources class searches the classpath for
that file, and then we pass it as a Reader to the DaoManagerBuilder

b

C

D

to get our

DaoManager instance. Now, for our DAO , we can simply call this: