即使数据库不存在,也可以使用Hibernate即时创建PostgreSQL数据库。 [英] Create PostgreSQL database on the fly using Hibernate even if the DB doesn't exist

查看:88
本文介绍了即使数据库不存在,也可以使用Hibernate即时创建PostgreSQL数据库。的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

使用H2,

Environment.HBM2DDL_AUTO, "create"

创建数据库(如果尚不存在)。

creates the database if it does not exist yet.

但是,在Postgres中,不存在的数据库未创建,因此引发了类似 DB不存在之类的异常。有没有一种方法可以配置Postgres按需创建不存在的数据库?

However, in Postgres, the non existing DB is not created and thus an exception which says something like "DB does not exist" is thrown. Is there a way to configure Postgres to create a non existing database on demand?

以下配置文件可用于重现该问题:

The following configuration files can be used to reproduce the problem:

使用H2可以正常工作:

Works fine using H2:

package test.postgressql;

import java.util.Properties;

import javax.sql.DataSource;

import org.hibernate.cfg.Environment;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateExceptionTranslator;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@PropertySource("file:C:/springconfig/qpmlib.properties")
@ComponentScan(basePackages = {"test.postgressql"})
@EnableJpaRepositories(basePackages = { "test.postgressql" })
@EnableTransactionManagement
public abstract class H2DBConfig {

    @Autowired
    org.springframework.core.env.Environment env;

    public static final String DB_NAME = getNewDBName();

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dmds = new DriverManagerDataSource();
        dmds.setDriverClassName("org.h2.Driver");
        dmds.setUrl("jdbc:h2:tcp://localhost/~/" + DB_NAME );
        dmds.setUsername(env.getProperty("h2user"));
        dmds.setPassword(env.getProperty("h2pw"));
        return dmds;
    }

    private static String getNewDBName() {
        return "H2DBTest";
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setDataSource(dataSource());
        factory.setPersistenceUnitName(DB_NAME);
        factory.setPackagesToScan("test.postgressql");
        factory.setJpaVendorAdapter(jpaAdapter());
        factory.setJpaProperties(jpaProperties());
        factory.afterPropertiesSet();
        return factory;
    }

    @Bean
    public PlatformTransactionManager transactionManager() {
        JpaTransactionManager txm = new JpaTransactionManager(
                entityManagerFactory().getObject());
        return txm;
    }

    @Bean
    public JpaVendorAdapter jpaAdapter() {
        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        adapter.setDatabase(Database.H2);
        adapter.setGenerateDdl(true);
        adapter.setShowSql(true);
        return adapter;
    }

    @Bean
    public HibernateExceptionTranslator exceptionTranslator() {
        return new HibernateExceptionTranslator();
    }

    public Properties jpaProperties() {
        Properties properties = new Properties();
        properties.put(Environment.SHOW_SQL, "true");
        properties.put(Environment.HBM2DDL_AUTO, "create");
        properties.put(Environment.DIALECT,"org.hibernate.dialect.H2Dialect");
        return properties;
    }

}

使用Postgres失败

Fails using Postgres

package test.postgressql;

import java.util.Properties;

import javax.sql.DataSource;

import org.hibernate.cfg.Environment;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateExceptionTranslator;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@PropertySource("file:C:/springconfig/qpmlib.properties")
@ComponentScan(basePackages = {"test.postgressql"})
@EnableJpaRepositories(basePackages = { "test.postgressql" })
@EnableTransactionManagement
public abstract class PGDBConfig {

    @Autowired
    org.springframework.core.env.Environment env;

    public static final String DB_NAME = getNewDBName();

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dmds = new DriverManagerDataSource();
        dmds.setDriverClassName("org.postgresql.Driver");
        dmds.setUrl("jdbc:postgresql://localhost:5432/" + DB_NAME);
        dmds.setUsername(env.getProperty("postgresuser"));
        dmds.setPassword(env.getProperty("postgrespw"));
        return dmds;
    }

    private static String getNewDBName() {
        return "PostgresDBTest";
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setDataSource(dataSource());
        factory.setPersistenceUnitName(DB_NAME);
        factory.setPackagesToScan("test.postgressql");
        factory.setJpaVendorAdapter(jpaAdapter());
        factory.setJpaProperties(jpaProperties());
        factory.afterPropertiesSet();
        return factory;
    }

    @Bean
    public PlatformTransactionManager transactionManager() {
        JpaTransactionManager txm = new JpaTransactionManager(
                entityManagerFactory().getObject());
        return txm;
    }

    @Bean
    public JpaVendorAdapter jpaAdapter() {
        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        adapter.setDatabase(Database.POSTGRESQL);
        adapter.setGenerateDdl(true);
        adapter.setShowSql(true);
        return adapter;
    }

    @Bean
    public HibernateExceptionTranslator exceptionTranslator() {
        return new HibernateExceptionTranslator();
    }

    public Properties jpaProperties() {
        Properties properties = new Properties();
        properties.put(Environment.SHOW_SQL, "true");
        properties.put(Environment.HBM2DDL_AUTO, "create");
        properties.put(Environment.DIALECT,"org.hibernate.dialect.PostgreSQL9Dialect");
        return properties;
    }
}


推荐答案

hbmddl 工具可以仅为现有模式创建表,而不能为您创建模式。在运行该工具之前,数据库必须存在。这是因为数据库必须由管理员创建,并且应该分配一个所有者。

The hbmddl tool can only create tables for an existing schema and it can't create a schema for you. The database must exist prior to running the tool. That's because a database must be created by an administrator and it should get an owner assigned.

由于在大多数应用程序中,该应用程序只能访问具有限制性特权的数据库角色,

Because in most applications, the application can only access a database role with restrictive privileges, there's no need for such a feature.

PostgreSQL不支持从连接URL即时创建数据库。您可以在应用程序启动时使用管理帐户和默认的PostgreSQL数据库添加 InitializingBean 连接到数据库服务器,如果应用程序数据库不存在,则发出CREATE DATABASE。或者,只需使用 Flyway

PostgreSQL doesn't support creating the database on-the-fly, from the connection URL. You can add an InitializingBean at application startup connecting to the database server using the administration account and the default PostgreSQL database and issue a CREATE DATABASE if the application DB doesn't exist. Or, just use Flyway for that.

这篇关于即使数据库不存在,也可以使用Hibernate即时创建PostgreSQL数据库。的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

查看全文
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆