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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002,2008 Oracle. All rights reserved.
*
* $Id: DataAccessor.java,v 1.1 2008/05/09 03:16:01 chao Exp $
*/
package persist.sqlapp;
import java.util.ArrayList;
import java.util.Iterator;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.persist.EntityCursor;
import com.sleepycat.persist.EntityIndex;
import com.sleepycat.persist.EntityJoin;
import com.sleepycat.persist.EntityStore;
import com.sleepycat.persist.ForwardCursor;
import com.sleepycat.persist.PrimaryIndex;
import com.sleepycat.persist.SecondaryIndex;
/**
* The data accessor class for the entity model.
*
* @author chao
*/
class DataAccessor {
/* Employee Accessors */
PrimaryIndex<Integer, Employee> employeeById;
SecondaryIndex<String, Integer, Employee> employeeByName;
SecondaryIndex<Float, Integer, Employee> employeeBySalary;
SecondaryIndex<Integer, Integer, Employee> employeeByManagerId;
SecondaryIndex<Integer, Integer, Employee> employeeByDepartmentId;
/* Department Accessors */
PrimaryIndex<Integer, Department> departmentById;
SecondaryIndex<String, Integer, Department> departmentByName;
/** Opens all primary and secondary indices. */
public DataAccessor(EntityStore store)
throws DatabaseException {
/* Primary key for Employee classes. */
employeeById =
store.getPrimaryIndex(Integer.class, Employee.class);
/* Secondary key for Employee classes. */
employeeByName = store.getSecondaryIndex(employeeById,
String.class,
"employeeName");
employeeBySalary = store.getSecondaryIndex(employeeById,
Float.class,
"salary");
employeeByManagerId = store.getSecondaryIndex(employeeById,
Integer.class,
"managerId");
employeeByDepartmentId = store.getSecondaryIndex(employeeById,
Integer.class,
"departmentId");
/* Primary key for Department classes. */
departmentById =
store.getPrimaryIndex(Integer.class, Department.class);
/* Secondary key for Department classes. */
departmentByName = store.getSecondaryIndex(departmentById,
String.class,
"departmentName");
}
/**
* Do prefix query, similar to the SQL statement:
* <blockquote><pre>
* SELECT * FROM table WHERE col LIKE 'prefix%';
* </pre></blockquote>
*
* @param index
* @param prefix
* @return
* @throws DatabaseException
*/
public <V> EntityCursor<V> doPrefixQuery(EntityIndex<String, V> index,
String prefix)
throws DatabaseException {
assert (index != null);
assert (prefix.length() > 0);
/* Opens a cursor for traversing entities in a key range. */
char[] ca = prefix.toCharArray();
final int lastCharIndex = ca.length - 1;
ca[lastCharIndex]++;
return doRangeQuery(index, prefix, true, String.valueOf(ca), false);
}
/**
* Do range query, similar to the SQL statement:
* <blockquote><pre>
* SELECT * FROM table WHERE col >= fromKey AND col <= toKey;
* </pre></blockquote>
*
* @param index
* @param fromKey
* @param fromInclusive
* @param toKey
* @param toInclusive
* @return
* @throws DatabaseException
*/
public <K, V> EntityCursor<V> doRangeQuery(EntityIndex<K, V> index,
K fromKey,
boolean fromInclusive,
K toKey,
boolean toInclusive)
throws DatabaseException {
assert (index != null);
/* Opens a cursor for traversing entities in a key range. */
return index.entities(fromKey,
fromInclusive,
toKey,
toInclusive);
}
/**
* Do a "AND" join on a single primary database, similar to the SQL:
* <blockquote><pre>
* SELECT * FROM table WHERE col1 = key1 AND col2 = key2;
* </pre></blockquote>
*
* @param pk
* @param sk1
* @param key1
* @param sk2
* @param key2
* @return
* @throws DatabaseException
*/
public <PK, SK1, SK2, E> ForwardCursor<E>
doTwoConditionsJoin(PrimaryIndex<PK, E> pk,
SecondaryIndex<SK1, PK, E> sk1,
SK1 key1,
SecondaryIndex<SK2, PK, E> sk2,
SK2 key2)
throws DatabaseException {
assert (pk != null);
assert (sk1 != null);
assert (sk2 != null);
EntityJoin<PK, E> join = new EntityJoin<PK, E>(pk);
join.addCondition(sk1, key1);
join.addCondition(sk2, key2);
return join.entities();
}
/**
* Do a natural join on Department and Employee by DepartmentId, similar to
* the SQL:
* <blockquote><pre>
* SELECT * FROM employee e, department d
* WHERE e.departmentId = d.departmentId;
* </pre></blockquote>
*
* @param iterable
* @throws DatabaseException
*/
public void doDepartmentEmployeeJoin(Iterable<Department> iterable)
throws DatabaseException {
/* Do a filter on Department by DepartmentName. */
Iterator<Department> deptIter = iterable.iterator();
while (deptIter.hasNext()) {
Department dept = deptIter.next();
/* Do a natural join on Department and Employee by DepartmentId. */
EntityCursor<Employee> empCursor = this.employeeByDepartmentId.
subIndex(dept.getDepartmentId()).entities();
Iterator<Employee> empIter = empCursor.iterator();
while (empIter.hasNext()) {
System.out.println(empIter.next());
}
empCursor.close();
}
System.out.println();
}
/**
* Query the Employee database by Department's secondary-key: deptName.
*
* @param deptName
* @throws DatabaseException
*/
public void getEmployeeByDeptName(String deptName)
throws DatabaseException {
EntityCursor<Department> deptCursor =
doRangeQuery(this.departmentByName, deptName, true, deptName, true);
doDepartmentEmployeeJoin(deptCursor);
deptCursor.close();
}
/**
* Query the Employee database by adding a filter on Department's
* non-secondary-key: deptLocation.
*
* @param deptLocation
* @throws DatabaseException
*/
public void getEmployeeByDeptLocation(String deptLocation)
throws DatabaseException {
/* Do a filter on Department by DepartmentName. */
ArrayList<Department> list = new ArrayList<Department>();
Iterator<Department> it =
this.departmentById.sortedMap().values().iterator();
while (it.hasNext()) {
Department dept = it.next();
if (dept.getLocation().equals(deptLocation)) {
list.add(dept);
}
}
doDepartmentEmployeeJoin(list);
}
}
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