276 lines
8.6 KiB
Java
276 lines
8.6 KiB
Java
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/*-
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* Copyright (C) 2002, 2017, Oracle and/or its affiliates. All rights reserved.
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*
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* This file was distributed by Oracle as part of a version of Oracle Berkeley
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* DB Java Edition made available at:
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*
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* http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
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*
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* Please see the LICENSE file included in the top-level directory of the
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* appropriate version of Oracle Berkeley DB Java Edition for a copy of the
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* license and additional information.
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*/
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package persist;
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import static com.sleepycat.persist.model.Relationship.MANY_TO_ONE;
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import java.io.File;
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import java.util.Calendar;
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import java.util.Date;
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import java.util.HashSet;
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import java.util.Random;
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import java.util.Set;
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import com.sleepycat.je.DatabaseException;
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import com.sleepycat.je.Environment;
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import com.sleepycat.je.EnvironmentConfig;
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import com.sleepycat.je.Transaction;
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import com.sleepycat.persist.EntityCursor;
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import com.sleepycat.persist.EntityStore;
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import com.sleepycat.persist.PrimaryIndex;
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import com.sleepycat.persist.SecondaryIndex;
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import com.sleepycat.persist.StoreConfig;
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import com.sleepycat.persist.model.Entity;
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import com.sleepycat.persist.model.PrimaryKey;
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import com.sleepycat.persist.model.SecondaryKey;
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/**
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* EventExampleDPL is a trivial example which stores Java objects that
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* represent an event. Events are primarily indexed by a timestamp, but have
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* other attributes, such as price, account reps, customer name and
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* quantity. Some of those other attributes are indexed.
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* <p>
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* The example simply shows the creation of a BDB environment and database,
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* inserting some events, and retrieving the events using the Direct
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* Persistence layer.
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* <p>
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* This example is meant to be paired with its twin, EventExample.java.
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* EventExample.java and EventExampleDPL.java perform the same functionality,
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* but use the Base API and the Direct Persistence Layer API, respectively.
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* This may be a useful way to compare the two APIs.
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* <p>
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* To run the example:
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* <pre>
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* javac EventExampleDPL.java
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* java EventExampleDPL -h <environmentDirectory>
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* </pre>
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*/
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public class EventExampleDPL {
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/*
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* The Event class embodies our example event and is the application
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* data. The @Entity annotation indicates that this class defines the
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* objects stored in a BDB database.
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*/
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@Entity
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static class Event {
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@PrimaryKey
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private Date time;
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@SecondaryKey(relate=MANY_TO_ONE)
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private int price;
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private Set<String> accountReps;
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private String customerName;
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private int quantity;
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Event(Date time,
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int price,
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String customerName) {
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this.time = time;
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this.price = price;
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this.customerName = customerName;
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this.accountReps = new HashSet<String>();
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}
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private Event() {} // For deserialization
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void addRep(String rep) {
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accountReps.add(rep);
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}
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@Override
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public String toString() {
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StringBuilder sb = new StringBuilder();
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sb.append("time=").append(time);
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sb.append(" price=").append(price);
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sb.append(" customerName=").append(customerName);
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sb.append(" reps=");
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if (accountReps.size() == 0) {
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sb.append("none");
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} else {
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for (String rep: accountReps) {
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sb.append(rep).append(" ");
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}
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}
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return sb.toString();
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}
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}
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/* A BDB environment is roughly equivalent to a relational database. */
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private Environment env;
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private EntityStore store;
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/*
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* Event accessors let us access events by the primary index (time)
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* as well as by the rep and price fields
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*/
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PrimaryIndex<Date,Event> eventByTime;
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SecondaryIndex<Integer,Date,Event> eventByPrice;
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/* Used for generating example data. */
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private Calendar cal;
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/*
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* First manually make a directory to house the BDB environment.
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* Usage: java EventExampleDPL -h <envHome>
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* All BDB on-disk storage is held within envHome.
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*/
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public static void main(String[] args)
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throws DatabaseException {
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if (args.length != 2 || !"-h".equals(args[0])) {
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System.err.println
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("Usage: java " + EventExampleDPL.class.getName() +
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" -h <envHome>");
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System.exit(2);
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}
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EventExampleDPL example = new EventExampleDPL(new File(args[1]));
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example.run();
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example.close();
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}
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private EventExampleDPL(File envHome)
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throws DatabaseException {
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/* Open a transactional Berkeley DB engine environment. */
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System.out.println("-> Creating a BDB environment");
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EnvironmentConfig envConfig = new EnvironmentConfig();
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envConfig.setAllowCreate(true);
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envConfig.setTransactional(true);
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env = new Environment(envHome, envConfig);
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/* Initialize the data access object. */
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init();
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cal = Calendar.getInstance();
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}
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/**
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* Create all primary and secondary indices.
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*/
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private void init()
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throws DatabaseException {
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/* Open a transactional entity store. */
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System.out.println("-> Creating a BDB database");
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StoreConfig storeConfig = new StoreConfig();
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storeConfig.setAllowCreate(true);
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storeConfig.setTransactional(true);
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store = new EntityStore(env, "ExampleStore", storeConfig);
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eventByTime = store.getPrimaryIndex(Date.class, Event.class);
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eventByPrice = store.getSecondaryIndex(eventByTime,
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Integer.class,
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"price");
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}
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private void run()
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throws DatabaseException {
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Random rand = new Random();
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/*
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* Create a set of events. Each insertion is a separate, auto-commit
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* transaction.
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*/
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System.out.println("-> Inserting 4 events");
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eventByTime.put(new Event(makeDate(1), 100, "Company_A"));
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eventByTime.put(new Event(makeDate(2), 2, "Company_B"));
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eventByTime.put(new Event(makeDate(3), 20, "Company_C"));
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eventByTime.put(new Event(makeDate(4), 40, "CompanyD"));
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/* Load a whole set of events transactionally. */
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Transaction txn = env.beginTransaction(null, null);
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int maxPrice = 50;
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System.out.println("-> Inserting some randomly generated events");
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for (int i = 0; i < 25; i++) {
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Event e = new Event(makeDate(rand.nextInt(365)),
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rand.nextInt(maxPrice),
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"Company_X");
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if ((i%2) ==0) {
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e.addRep("Bob");
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e.addRep("Nikunj");
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} else {
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e.addRep("Yongmin");
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}
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eventByTime.put(e);
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}
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txn.commitWriteNoSync();
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/*
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* Windows of events - display the events between June 1 and Aug 31
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*/
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System.out.println("\n-> Display the events between June 1 and Aug 31");
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Date startDate = makeDate(Calendar.JUNE, 1);
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Date endDate = makeDate(Calendar.AUGUST, 31);
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EntityCursor<Event> eventWindow =
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eventByTime.entities(startDate, true, endDate, true);
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printEvents(eventWindow);
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/*
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* Display all events, ordered by a secondary index on price.
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*/
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System.out.println("\n-> Display all events, ordered by price");
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EntityCursor<Event> byPriceEvents = eventByPrice.entities();
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printEvents(byPriceEvents);
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}
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private void close()
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throws DatabaseException {
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store.close();
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env.close();
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}
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/**
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* Print all events covered by this cursor.
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*/
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private void printEvents(EntityCursor<Event> eCursor)
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throws DatabaseException {
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try {
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for (Event e: eCursor) {
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System.out.println(e);
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}
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} finally {
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/* Be sure to close the cursor. */
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eCursor.close();
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}
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}
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/**
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* Little utility for making up java.util.Dates for different days, just
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* to generate test data.
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*/
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private Date makeDate(int day) {
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cal.set((Calendar.DAY_OF_YEAR), day);
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return cal.getTime();
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}
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/**
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* Little utility for making up java.util.Dates for different days, just
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* to make the test data easier to read.
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*/
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private Date makeDate(int month, int day) {
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cal.set((Calendar.MONTH), month);
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cal.set((Calendar.DAY_OF_MONTH), day);
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return cal.getTime();
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}
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}
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