Javadoc update using "DB"

This commit is contained in:
rob bygrave
2019-03-07 11:25:34 +13:00
parent aa1e021501
commit a5f435dbcf
2 changed files with 47 additions and 89 deletions
+44
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@@ -17,6 +17,50 @@ import java.util.Map;
import java.util.Set;
import java.util.concurrent.Callable;
/**
* DB is a registry of {@link Database} by name.
* <p>
* DB additionally provides a convenient way to use the 'default' Database.
* <p>
* <h3>Default database</h3>
* <p>
* One of the Database instances can be registered as the "default database"
* and can be obtained using <code>DB.getDefault()</code>
* </p>
* <pre>{@code
*
* Database database = DB.getDefault();
*
* }</pre>
*
* <h3>Named database</h3>
* <p>
* Multiple database instances can be registered with DB and we can obtain them
* using <code>DB.byName()</code>
* </p>
* <pre>{@code
*
* Database hrDatabase = DB.byName("hr");
*
* }</pre>
*
* <h3>Convenience methods</h3>
* <p>
* DB has methods like {@link #find(Class)} and {@link #save(Object)} which are
* just convenience for using the default database.
* </p>
*
* <pre>{@code
*
* // fetch using the default database
* Order order = DB.find(Order.class, 10);
*
* // is the same as
* Database database = DB.getDefault();
* Order order = database.find(Order.class, 10);
*
* }</pre>
*/
public class DB {
/**
+3 -89
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@@ -24,97 +24,11 @@ import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
/**
* This Ebean object is effectively a singleton that holds a map of registered
* {@link EbeanServer}s. It additionally provides a convenient way to use the
* 'default' EbeanServer.
* Ebean is a registry of {@link Database} by name. Ebean has now been renamed to {@link DB}.
* <p>
* If you are using a Dependency Injection framework such as
* <strong>Spring</strong> or <strong>Guice</strong> you will probably
* <strong>NOT</strong> use this Ebean singleton object. Instead you will
* configure and construct EbeanServer instances using {@link ServerConfig} and
* {@link EbeanServerFactory} and inject those EbeanServer instances into your
* data access objects.
* </p>
* Ebean is effectively this is an alias for {@link DB} which is the new and improved name for Ebean.
* <p>
* In documentation "Ebean singleton" refers to this object.
* </p>
* <ul>
* <li>There is one EbeanServer per Database (javax.sql.DataSource).</li>
* <li>EbeanServers can be 'registered' with the Ebean singleton (put into its
* map). Registered EbeanServer's can later be retrieved via
* {@link #getServer(String)}.</li>
* <li>One EbeanServer can be referred to as the 'default' EbeanServer. For
* convenience, the Ebean singleton (this object) provides methods such as
* {@link #find(Class)} that proxy through to the 'default' EbeanServer. This
* can be useful for applications that use a single database.</li>
* </ul>
* <p>
* For developer convenience Ebean has static methods that proxy through to the
* methods on the <em>'default'</em> EbeanServer. These methods are provided for
* developers who are mostly using a single database. Many developers will be
* able to use the methods on Ebean rather than get a EbeanServer.
* </p>
* <p>
* EbeanServers can be created and used without ever needing or using the Ebean
* singleton. Refer to {@link ServerConfig#setRegister(boolean)}.
* </p>
* <p>
* You can either programmatically create/register EbeanServers via
* {@link EbeanServerFactory} or they can automatically be created and
* registered when you first use the Ebean singleton. When EbeanServers are
* created automatically they are configured using information in the
* ebean.properties file.
* </p>
* <pre>{@code
*
* // fetch shipped orders (and also their customer)
* List<Order> list = Ebean.find(Order.class)
* .fetch("customer")
* .where()
* .eq("status.code", Order.Status.SHIPPED)
* .findList();
*
* // read/use the order list ...
* for (Order order : list) {
* Customer customer = order.getCustomer();
* ...
* }
*
* }</pre>
* <pre>{@code
*
* // fetch order 10, modify and save
* Order order = Ebean.find(Order.class, 10);
*
* OrderStatus shipped = Ebean.getReference(OrderStatus.class,"SHIPPED");
* order.setStatus(shipped);
* order.setShippedDate(shippedDate);
* ...
*
* // implicitly creates a transaction and commits
* Ebean.save(order);
*
* }</pre>
* <p>
* When you have multiple databases and need access to a specific one the
* {@link #getServer(String)} method provides access to the EbeanServer for that
* specific database.
* </p>
* <pre>{@code
*
* // Get access to the Human Resources EbeanServer/Database
* EbeanServer hrDb = Ebean.getServer("hr");
*
* // fetch contact 3 from the HR database
* Contact contact = hrDb.find(Contact.class, 3);
*
* contact.setName("I'm going to change");
* ...
*
* // save the contact back to the HR database
* hrDb.save(contact);
*
* }</pre>
* The preference is to use DB and Database rather than Ebean and EbeanServer.
*/
public final class Ebean {
private static final Logger logger = LoggerFactory.getLogger(Ebean.class);