「ネイティブの日本語で以下の文章を言い換えてください。ただし、1つのオプションのみが必要です。「Hibernate Criteriaの実例のチュートリアル」

12か月 ago
芽依, 雨夜
6 minutes

「HibernateのCriteriaの例チュートリアルへようこそ。今日はHibernateのCriteriaについて見ていきます。」

ハイバネイトのクライテリアを利用する

ほとんどの場合、データベースのクエリと結果の取得にはHQLが使用されます。HQLは値の更新や削除には好まれる方法ではありません、なぜならその場合にはテーブル間の関連を考慮する必要があるからです。Hibernate Criteria APIは、データベースのクエリと結果の取得に対してオブジェクト指向のアプローチを提供します。HibernateではCriteriaを使用して更新または削除クエリやDDLステートメントを実行することはできません。HibernateのCriteriaクエリは、オブジェクト指向のアプローチを使用してデータベースから結果を取得するためにのみ使用されます。私のHibernateのCriteriaの例では、HQLの例と同じ設定を使用し、HibernateでCriteriaを使用してデータベースをクエリする方法を示します。Hibernate Criteria APIの一般的な使用法のいくつかは次のとおりです。

    1. Hibernate Criteria APIは、sum()、min()、max()などの集計関数に使用できるProjectionを提供します。

 

    1. Hibernate Criteria APIは、ProjectionListと組み合わせて選択した列のみを取得するために使用することができます。

 

    1. HibernateのCriteriaでは、複数のテーブルを結合して結果を取得するために使うことができます。Hibernateのcriteria結合において便利なメソッドとしてはcreateAlias()、setFetchMode()、setProjection()があります。

 

    1. HibernateのCriteria APIでは、条件を指定して結果を取得することができます。便利な方法としてはadd()メソッドを用いてRestrictionsを追加することができます。

 

    Hibernate Criteria APIは、結果の並び替えに使用できるaddOrder()メソッドを提供しています。

下のクラスは、Hibernate Criteria APIのさまざまな使用例を示しており、これらのほとんどはHQLチュートリアルの例の代替です。

package com.scdev.hibernate.main;

import java.util.Arrays;
import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.FetchMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.ProjectionList;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;

import com.scdev.hibernate.model.Employee;
import com.scdev.hibernate.util.HibernateUtil;

public class HibernateCriteriaExamples {

	@SuppressWarnings("unchecked")
	public static void main(String[] args) {
		// Prep work
		SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
		Session session = sessionFactory.getCurrentSession();
		Transaction tx = session.beginTransaction();

		//Get All Employees
		Criteria criteria = session.createCriteria(Employee.class);
		List<Employee> empList = criteria.list();
		for(Employee emp : empList){
			System.out.println("ID="+emp.getId()+", Zipcode="+emp.getAddress().getZipcode());
		}
		
		// Get with ID, creating new Criteria to remove all the settings
		criteria = session.createCriteria(Employee.class)
					.add(Restrictions.eq("id", new Long(3)));
		Employee emp = (Employee) criteria.uniqueResult();
		System.out.println("Name=" + emp.getName() + ", City="
				+ emp.getAddress().getCity());

		//Pagination Example
		empList = session.createCriteria(Employee.class)
					.addOrder(Order.desc("id"))
					.setFirstResult(0)
					.setMaxResults(2)
					.list();
		for(Employee emp4 : empList){
			System.out.println("Paginated Employees::"+emp4.getId()+","+emp4.getAddress().getCity());
		}

		//Like example
		empList = session.createCriteria(Employee.class)
				.add(Restrictions.like("name", "%i%"))
				.list();
		for(Employee emp4 : empList){
			System.out.println("Employees having 'i' in name::"+emp4.getName()+","+emp4.getAddress().getCity());
		}
		
		//Projections example
		long count = (Long) session.createCriteria(Employee.class)
				.setProjection(Projections.rowCount())
				.add(Restrictions.like("name", "%i%"))
				.uniqueResult();
		System.out.println("Number of employees with 'i' in name="+count);

		//using Projections for sum, min, max aggregation functions
		double sumSalary = (Double) session.createCriteria(Employee.class)
			.setProjection(Projections.sum("salary"))
			.uniqueResult();
		System.out.println("Sum of Salaries="+sumSalary);
		
		//Join example for selecting few columns
		criteria = session.createCriteria(Employee.class, "employee");
		criteria.setFetchMode("employee.address", FetchMode.JOIN);
		criteria.createAlias("employee.address", "address"); // inner join by default

		ProjectionList columns = Projections.projectionList()
						.add(Projections.property("name"))
						.add(Projections.property("address.city"));
		criteria.setProjection(columns);

		List<Object[]> list = criteria.list();
		for(Object[] arr : list){
			System.out.println(Arrays.toString(arr));
		}
		
		
		// Rollback transaction to avoid messing test data
		tx.commit();
		// closing hibernate resources
		sessionFactory.close();
	}

}

上記のHibernate Criteriaの例のプログラムを実行すると、以下の出力が得られます。

May 26, 2014 6:53:32 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {4.0.4.Final}
May 26, 2014 6:53:32 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {4.3.5.Final}
May 26, 2014 6:53:32 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
May 26, 2014 6:53:32 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
May 26, 2014 6:53:32 PM org.hibernate.cfg.Configuration configure
INFO: HHH000043: Configuring from resource: hibernate.cfg.xml
May 26, 2014 6:53:32 PM org.hibernate.cfg.Configuration getConfigurationInputStream
INFO: HHH000040: Configuration resource: hibernate.cfg.xml
May 26, 2014 6:53:32 PM org.hibernate.internal.util.xml.DTDEntityResolver resolveEntity
WARN: HHH000223: Recognized obsolete hibernate namespace https://hibernate.sourceforge.net/. Use namespace https://www.hibernate.org/dtd/ instead. Refer to Hibernate 3.6 Migration Guide!
May 26, 2014 6:53:32 PM org.hibernate.cfg.Configuration doConfigure
INFO: HHH000041: Configured SessionFactory: null
Hibernate Configuration loaded
Hibernate serviceRegistry created
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!)
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://localhost/TestDB]
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH000046: Connection properties: {user=scdev, password=****}
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH000006: Autocommit mode: false
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
INFO: HHH000115: Hibernate connection pool size: 20 (min=1)
May 26, 2014 6:53:32 PM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQLDialect
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.internal.LobCreatorBuilder useContextualLobCreation
INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4
May 26, 2014 6:53:32 PM org.hibernate.engine.transaction.internal.TransactionFactoryInitiator initiateService
INFO: HHH000399: Using default transaction strategy (direct JDBC transactions)
May 26, 2014 6:53:32 PM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init>
INFO: HHH000397: Using ASTQueryTranslatorFactory
Hibernate: select this_.emp_id as emp_id1_1_1_, this_.emp_name as emp_name2_1_1_, this_.emp_salary as emp_sala3_1_1_, address2_.emp_id as emp_id1_0_0_, address2_.address_line1 as address_2_0_0_, address2_.city as city3_0_0_, address2_.zipcode as zipcode4_0_0_ from EMPLOYEE this_ left outer join ADDRESS address2_ on this_.emp_id=address2_.emp_id
ID=1, Zipcode=95129
ID=2, Zipcode=95051
ID=3, Zipcode=560100
ID=4, Zipcode=100100
Hibernate: select this_.emp_id as emp_id1_1_1_, this_.emp_name as emp_name2_1_1_, this_.emp_salary as emp_sala3_1_1_, address2_.emp_id as emp_id1_0_0_, address2_.address_line1 as address_2_0_0_, address2_.city as city3_0_0_, address2_.zipcode as zipcode4_0_0_ from EMPLOYEE this_ left outer join ADDRESS address2_ on this_.emp_id=address2_.emp_id where this_.emp_id=?
Name=Lisa, City=Bangalore
Hibernate: select this_.emp_id as emp_id1_1_1_, this_.emp_name as emp_name2_1_1_, this_.emp_salary as emp_sala3_1_1_, address2_.emp_id as emp_id1_0_0_, address2_.address_line1 as address_2_0_0_, address2_.city as city3_0_0_, address2_.zipcode as zipcode4_0_0_ from EMPLOYEE this_ left outer join ADDRESS address2_ on this_.emp_id=address2_.emp_id order by this_.emp_id desc limit ?
Paginated Employees::4,New Delhi
Paginated Employees::3,Bangalore
Hibernate: select this_.emp_id as emp_id1_1_1_, this_.emp_name as emp_name2_1_1_, this_.emp_salary as emp_sala3_1_1_, address2_.emp_id as emp_id1_0_0_, address2_.address_line1 as address_2_0_0_, address2_.city as city3_0_0_, address2_.zipcode as zipcode4_0_0_ from EMPLOYEE this_ left outer join ADDRESS address2_ on this_.emp_id=address2_.emp_id where this_.emp_name like ?
Employees having 'i' in name::David,Santa Clara
Employees having 'i' in name::Lisa,Bangalore
Hibernate: select count(*) as y0_ from EMPLOYEE this_ where this_.emp_name like ?
Number of employees with 'i' in name=2
Hibernate: select sum(this_.emp_salary) as y0_ from EMPLOYEE this_
Sum of Salaries=1000.0
Hibernate: select this_.emp_name as y0_, address1_.city as y1_ from EMPLOYEE this_ inner join ADDRESS address1_ on this_.emp_id=address1_.emp_id
[Pankaj, San Jose]
[David, Santa Clara]
[Lisa, Bangalore]
[Jack, New Delhi]
May 26, 2014 6:53:32 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop
INFO: HHH000030: Cleaning up connection pool [jdbc:mysql://localhost/TestDB]

HQLのサンプルプロジェクトを使用しているため、それをインポートし、このクラスを追加する必要があります。出力されたHibernateクエリに注意して、クエリを洗練させて求めている結果を得ることができます。これで、HibernateのCriteriaについての簡単なまとめは以上です。

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