SimpleEbeanService.java

package sscce;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.Entity;
import javax.persistence.Id;

import com.avaje.ebean.EbeanServer;
import com.avaje.ebean.EbeanServerFactory;
import com.avaje.ebean.Query;
import com.avaje.ebean.QueryIterator;
import com.avaje.ebean.config.AutofetchConfig;
import com.avaje.ebean.config.DataSourceConfig;
import com.avaje.ebean.config.ServerConfig;
import com.avaje.ebeaninternal.server.core.DefaultServer;
import com.avaje.ebeaninternal.server.ddl.DdlGenerator;

/**
 * <h1>Simple Database Service with Ebean ORM</h1>
 *
 * <p>This Short, Self Contained, Correct Example (SSCCE) shows three pitfalls I
 * stumpled upon.
 *
 * <p><b>Required Libraries:</b> ebean-2.7.4.jar, h2-1.3.164.jar, persistence-api-1.0.jar,
 * servlet-api-2.5.jar.
 *
 * <h2>Pitfall #1: Used special characters in the name of ServerConfig</h2>
 *
 * <pre>
 * WRONG:
 *   this.serverConfig.setName("h2:mem:ebean");
 *   this.serverConfig.setName("h2.mem.ebean");
 *
 * RIGHT:
 *   this.serverConfig.setName(this.sluggifyText("h2:mem:ebean"));
 * </pre>
 *
 * <h2>Pitfall #2: Forgot to implement getters and setters in the entity bean</h2>
 *
 * <pre>
 * WRONG:
 *   france.capitalName = "Paris";
 *   System.out.println(france.capitalName);
 *   this.ebeanServer.insert(france);
 *
 * RIGHT:
 *   france.setCapitalName("Paris");
 *   System.out.println(france.getCapitalName());
 *   this.ebeanServer.insert(france);
 * </pre>
 *
 * <h2>Pitfall #3. Connection in QueryIterator wasn't closed</h2>
 *
 * <pre>
 * WRONG:
 *   QueryIterator<Country> queryIterator = query.findIterate();
 *
 * RIGHT:
 *   QueryIterator<Country> queryIterator = query.findIterate();
 *   queryIterator.close();
 * </pre>
 */
public class SimpleEbeanService {

    //-----------------------------------------------------------------------------------
    // MAIN METHOD.
    //-----------------------------------------------------------------------------------

    public static void main(String[] args) {
        SimpleEbeanService service = new SimpleEbeanService();

        System.out.println("Initializing database...");
        service.addEntityClass(Country.class);
        service.initDataSourceConfig();
        service.initAutofetchConfig();
        service.initServerConfig();

        System.out.println("Connecting to database...");
        service.initEbeanServer();

        System.out.println("Running queries...");
        service.runCreateTableQueries();
        service.runInsertDatasetQuery();
        service.runSelectDatasetQueries();
    }

    //-----------------------------------------------------------------------------------
    // PUBLIC FIELDS.
    //-----------------------------------------------------------------------------------

    public int maxConnections = 5;
    public int numberOfQueries = 20;

    public List<Class<?>> entityClasses = new ArrayList<Class<?>>();
    public DataSourceConfig dataSourceConfig;
    public AutofetchConfig autofetchConfig;
    public ServerConfig serverConfig;
    public EbeanServer ebeanServer;

    //-----------------------------------------------------------------------------------
    // PUBLIC METHODS.
    //-----------------------------------------------------------------------------------

    public void addEntityClass(Class<?> entityClass) {
        this.entityClasses.add(entityClass);
    }

    public void initDataSourceConfig() {
        this.dataSourceConfig = new DataSourceConfig();
        this.dataSourceConfig.setDriver("org.h2.Driver");
        this.dataSourceConfig.setUrl("jdbc:h2:mem:ebean");
        this.dataSourceConfig.setUsername("sa");
        this.dataSourceConfig.setPassword("");
        this.dataSourceConfig.setMaxConnections(this.maxConnections);
    }

    public void initAutofetchConfig() {
        this.autofetchConfig = new AutofetchConfig();
        this.autofetchConfig.setUseFileLogging(false);
        this.autofetchConfig.setLogDirectory(".");
    }

    public void initServerConfig() {
        this.serverConfig = new ServerConfig();
        this.serverConfig.setLoggingToJavaLogger(true);
        this.serverConfig.setLoggingDirectory(".");

        this.serverConfig.setDataSourceConfig(this.dataSourceConfig);
        this.serverConfig.setAutofetchConfig(this.autofetchConfig);

        // PITFALL #1:
        // javax.management.MalformedObjectNameException: Invalid character ':' in
        // value part of property
        //this.serverConfig.setName("h2:mem:ebean");

        // PITFALL #1:
        // java.lang.ClassFormatError: Illegal class name "sscce/SimpleEbeanService
        // $Country$$EntityBean$h2.mem.ebean" in class file sscce/SimpleEbeanService
        // $Country$$EntityBean$h2/mem/ebean
        //this.serverConfig.setName("h2.mem.ebean");

        this.serverConfig.setName(this.sluggifyText("h2:mem:ebean"));
        this.serverConfig.setRegister(false);
        this.serverConfig.setDefaultServer(false);

        this.serverConfig.setClasses(this.entityClasses);
        this.serverConfig.setDdlGenerate(false);
        this.serverConfig.setDdlRun(false);
    }

    public void initEbeanServer() {
        this.ebeanServer = EbeanServerFactory.create(this.serverConfig);
    }

    public void runCreateTableQueries() {
        DdlGenerator generator = ((DefaultServer) this.ebeanServer).getDdlGenerator();
        generator.runScript(true, generator.generateDropDdl());
        generator.runScript(false, generator.generateCreateDdl());
    }

    public void runInsertDatasetQuery() {
        Country france = new Country();
        france.setName("France");
        france.setCapitalName("Paris");

        // PITFALL #2:
        // Exception in thread "main" java.lang.RuntimeException: get id on [sscce.
        // SimpleEbeanService$Country] type[sscce.SimpleEbeanService$Country] threw error.
        this.ebeanServer.insert(france);
    }

    public void runSelectDatasetQueries() {
        for (int index = 0; index < this.numberOfQueries; index += 1) {
            Query<Country> query = this.ebeanServer.createQuery(Country.class)
                .select("name, capitalName").where().eq("name", "France").query();
            QueryIterator<Country> queryIterator = query.findIterate();
            try {
                while (queryIterator.hasNext()) {
                    Country country = queryIterator.next();
                    System.out.println(country);
                }
            }
            finally {
                // PITFALL #3:
                // Exception in thread "main" javax.persistence.PersistenceException:
                // java.sql.SQLException: Unsuccessfully waited [1000] millis for a
                // connection to be returned. No connections are free. You need to
                // Increase the max connections of [5] or look for a connection pool
                // leak using datasource.xxx.capturestacktrace=true
                queryIterator.close();
            }
        }
    }

    //-----------------------------------------------------------------------------------
    // PRIVATE METHODS.
    //-----------------------------------------------------------------------------------

    private String sluggifyText(String text) {
        text = text.toLowerCase();
        text = text.replaceAll("[^a-z0-9]+", "_");
        text = text.replaceAll("_$|^_", "");
        return text;
    }

    //-----------------------------------------------------------------------------------
    // PUBLIC CLASSES.
    //-----------------------------------------------------------------------------------

    @Entity
    public static class Country {
        private @Id Integer id;
        private String name;
        private String capitalName;

        public Integer getId() { return id; }
        public void setId(Integer id) { this.id = id; }

        public String getName() { return name; }
        public void setName(String name) { this.name = name; }

        public String getCapitalName() { return capitalName; }
        public void setCapitalName(String capitalName) { this.capitalName = capitalName; }

        public String toString() {
            return "<Country name='" + this.name + "' " +
                "capitalName='" + this.capitalName + "'>";
        }
    }

}