import java.io.IOException;
import java.io.Serializable;
import jdbm.PrimaryStoreMap;
import jdbm.RecordManager;
import jdbm.RecordManagerFactory;
import jdbm.SecondaryKeyExtractor;
import jdbm.SecondaryTreeMap;
/**
* More advanced example to demonstrate Map usage.
*
* @author Jan Kotek
*
*/
public class HelloWorld2 {
static class Person implements Serializable{
/** never forget this, very important for serialization*/
private static final long serialVersionUID = -3321252970661193623L;
final String name;
final String town;
final String country;
/** some data to object class bigger */
final byte[] balast = new byte[1024];
public Person(String name, String town, String country) {
this.name = name;
this.town = town;
this.country = country;
}
@Override
public String toString() {
return "Person [name=" + name + ", town=" + town + ", country=" + country + "]";
}
/** snip getters and setters*/
}
public static void main(String[] args) throws IOException {
RecordManager recman = RecordManagerFactory.
createRecordManager("HelloWorld2");
/**
* Create primary map which is used to store records.
* Data can be also stored in PrimaryTreeMap and PrimaryHashMap,
* but this is more efficient for large objects.
*/
PrimaryStoreMap<Long,Person> main = recman.storeMap("recman");
/**
* Create secondary index which points to Person name.
* SecondaryMap is readonly, it is updated by PrimaryMap.
*
* Secondary map have three types,
* first is type of secondary index (string),
* second and third are copied from primary map.
*/
SecondaryTreeMap<String, Long, Person> nameIndex = main.secondaryTreeMap("nameIndex",
new SecondaryKeyExtractor<String, Long, Person>() {
public String extractSecondaryKey(Long key, Person value) {
return value.name;
}
});
/**
* Another secondary map which points to town and country
*/
SecondaryTreeMap<String, Long, Person> townIndex = main.secondaryTreeMap("townIndex",
new SecondaryKeyExtractor<String, Long, Person>() {
public String extractSecondaryKey(Long key, Person value) {
/**
* Note format of map key
*/
return value.country+"/"+value.town;
}
});
/**
* And very simple index of Evil family members
*/
SecondaryTreeMap<Boolean, Long, Person> evilIndex = main.secondaryTreeMap("evilIndex",
new SecondaryKeyExtractor<Boolean, Long, Person>() {
public Boolean extractSecondaryKey(Long key, Person value) {
return value.name.contains("Evil");
}
});
/**
* Clean up, if this example was run more times.
* All secondary indexes are updated automatically.
*/
main.clear();
/**
* Add some data.
* StoreMap does not have usuall 'put' method.
* Key is generated by Store, so use 'putValue' instead
*/
main.putValue(new Person("James Bond","London","UK"));
main.putValue(new Person("Austin Powers","London","UK"));
main.putValue(new Person("Dr Evil","Vulcano Island","Ocean"));
main.putValue(new Person("Scott Evil","Vulcano Island","Ocean"));
main.putValue(new Person("Vanessa Kensington","London","UK"));
main.putValue(new Person("Alotta Fagina","Las Vegas","USA"));
/**
* Persists inserted values
*/
recman.commit();
/**
* Get persons with name Austin Powers
*/
System.out.println();
System.out.println("Austin Powers: ");
for(Person person:nameIndex.getPrimaryValues("Austin Powers")){
System.out.println(" "+person);
}
/**
* Print all Persons who lives on Vulcano Island.
* First we must obtain key from primary map,
* then
*/
System.out.println();
System.out.println("Persons on Vulcano Island: ");
for(Person person:townIndex.getPrimaryValues("Ocean/Vulcano Island")){
System.out.println(" "+person);
}
/**
* Get everyone who is Evil
*/
System.out.println();
System.out.println("Evil family: ");
for(Person person:evilIndex.getPrimaryValues(true)){
System.out.println(" "+person);
}
recman.close();
}
}