在 Spring Boot 中编写自定义查询
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【中文标题】在 Spring Boot 中编写自定义查询【英文标题】:writing custom queries in Spring boot 【发布时间】:2016-03-22 02:11:31 【问题描述】:我最近开始使用 Spring boot,但遇到了一些问题。以前,当我只是将 Spring 数据与 hibernate 和 JPA 一起使用时,我可以创建一个 hibernate.cfg.xml 文件,该文件将提供一堆可以传递给配置对象的配置,然后最终创建一个 SessionFactory 对象,该对象将创建一个可用于将查询传递给休眠的会话对象:
package util;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
public class HibernateUtil
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory()
try
// Create the SessionFactory from hibernate.cfg.xml
Configuration configuration = new Configuration().configure("hibernate.cfg.xml"); return configuration.buildSessionFactory( new
StandardServiceRegistryBuilder().applySettings( configuration.getProperties() ).build() );
catch (Throwable ex)
// Make sure you log the exception, as it might be swallowed System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex);
public static SessionFactory getSessionFactory() return sessionFactory;
hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/hello-world</property>
<property name="connection.username">root</property>
<property name="connection.password">password</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Create/update tables automatically using mapping metadata -->
<property name="hbm2ddl.auto">update</property>
<!-- Use Annotation-based mapping metadata -->
<mapping class="entity.Author"/>
<mapping class="entity.Article"/>
</session-factory>
</hibernate-configuration>
Main.java
public class HelloWorldClient
public static void main(String[] args)
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction txn = session.getTransaction();
EntityManagerFactory emf = Persiscance.createEntityManagerFactory("hibernate.cfg.xml");
EntityManager em = emf.createEntityManager();
EntityTransaction txn = em.getTransaction();
try
txn.begin();
Author author = new Author("name", listOfArticlesWritten);
Article article = new Article("Article Title", author);
session.save(author);
session.save(article);
Query query = session.createQuery("select distinct a.authorName from Article s
where s.author like "Joe%" and title = 'Spring boot');
List<Article> articles = query.list();
txn.commit();
catch(Exception e)
if(txn != null) txn.rollback();
e.printStackTrace();
finally
if(session != null) session.close();
这就是问题出现的地方。我不知道如何避免为自定义查询创建 hibernate.cfg.xml 文件或会话工厂。在 Spring 指南页面和我已经完成的一些教程中,他们采用了他们的 DAO 并扩展了 CrudRepository 接口,该接口已经提供了一堆方法,以及一种命名方法的方法,以便 Hibernate 可以自己构建 sql .
我想要完成的,至少在这篇文章中是能够在 Spring Boot 中执行上述查询。我可以创建一个属性文件
application.properties
# ===============================
# = DATA SOURCE
# ===============================
# Set here configurations for the database connection
spring.datasource.url = jdbc:mysql://localhost:3306/spring-boot-demo
spring.datasource.username = test
spring.datasource.password = test
# Mysql connector
spring.datasource.driverClassName = com.mysql.jdbc.Driver
# ===============================
# = JPA / HIBERNATE
# ===============================
# Specify the DBMS
spring.jpa.database = MYSQL
# Show or not log for each sql query
spring.jpa.show-sql = true
# Ddl auto must be set to "create" to ensure that Hibernate will run the
# import.sql file at application startup
#create-drop| update | validate | none
spring.jpa.hibernate.ddl-auto = update
# SQL dialect for generating optimized queries
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
# ===============================
# = THYMELEAF
# ===============================
spring.thymeleaf.cache = false
#debug=true
我可以将除映射之外的所有内容移至属性文件,但由于不再有会话对象,我不清楚如何编写查询。
【问题讨论】:
也许你需要自定义方法实现。 this is an *** answer 我在这里解释了解决方案,可能对你有帮助***.com/a/48854352/4720910 【参考方案1】:如果您使用 Spring Boot + Spring Data JPA,则使用 spring.datasource.*
properties 将数据源(现在放入 hibernate.cfg.xml)配置到 application.properties
。
这应该会自动为您创建一个实体管理器。如果需要使用查询,可以使用 Spring Data JPA 的存储库,例如:
public interface ArticleRepository extends JpaRepository<Article, Long>
@Query("select s from Article s where s.author like ?1 and s.title = ?2")
List<Article> findByAuthorAndTitle(String author, String title);
现在您可以自动装配存储库并使用给定的查询,如下所示:
List<Article> articles = repository.findByAuthorAndTitle("Joe%", "Spring boot");
如果您确实需要自定义查询,可以使用 JPA 的 Predicate/Criteria API。 Spring 提供了这些谓词的包装版本,称为 Specifications。
为此,您可以使用另一个名为 JpaSpecificationExecutor<Article>
的接口扩展您的 ArticleRepository
。这会为您的存储库添加一些额外的方法:
Specification<Article> spec = Specifications.<Article>where((root, query, cb) ->
return cb.and(
cb.like(root.get("author"), "Joe%"),
cb.equal(root.get("title"), "Spring boot"));
);
List<Article> articles = repository.findAll(spec);
这允许您动态创建查询,尽管从您的问题来看,您似乎并不真正需要它。
【讨论】:
【参考方案2】:在 Spring Boot 应用程序中,您无需创建 xml 配置,您必须自己配置 java 文件。 看看这个例子,
import java.util.Properties;
import javax.sql.DataSource;
import org.hibernate.annotations.common.util.impl.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateTransactionManager;
import org.springframework.orm.hibernate4.LocalSessionFactoryBean;
@Configuration
public class DatabaseConfig
private org.jboss.logging.Logger log = LoggerFactory.logger(DatabaseConfig.class);
@Value("$db.driver")
private String DB_DRIVER;
@Value("$db.username")
private String DB_USERNAME;
@Value("$db.password")
private String DB_PASSWORD;
@Value("$db.url")
private String DB_URL;
@Value("$hibernate.dialect")
private String HIBERNATE_DIALECT;
@Value("$hibernate.show_sql")
private String HIBERNATE_SHOW_SQL;
@Value("$hibernate.hbm2ddl.auto")
private String HIBERNATE_HBM2DDL_AUTO;
@Value("$entitymanager.packagesToScan")
private String ENTITYMANAGER_PACKAGES_TO_SCAN;
@Bean
public DataSource dataSource()
DriverManagerDataSource dataSource = null;
try
dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName(DB_DRIVER);
dataSource.setUrl(DB_URL);
dataSource.setUsername(DB_USERNAME);
dataSource.setPassword(DB_PASSWORD);
catch (Exception e)
e.getMessage();
return dataSource;
@Bean
public LocalSessionFactoryBean sessionFactory()
LocalSessionFactoryBean sessionFactoryBean = new LocalSessionFactoryBean();
sessionFactoryBean.setDataSource(dataSource());
sessionFactoryBean.setPackagesToScan(ENTITYMANAGER_PACKAGES_TO_SCAN);
Properties hibernateProps = new Properties();
hibernateProps.put("hibernate.dialect", HIBERNATE_DIALECT);
hibernateProps.put("hibernate.show_sql", HIBERNATE_SHOW_SQL);
hibernateProps.put("hibernate.hbm2ddl.auto", HIBERNATE_HBM2DDL_AUTO);
sessionFactoryBean.setHibernateProperties(hibernateProps);
return sessionFactoryBean;
@Bean
public HibernateTransactionManager transactionManager()
HibernateTransactionManager transactionManager = new HibernateTransactionManager();
transactionManager.setSessionFactory(sessionFactory().getObject());
return transactionManager;
【讨论】:
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