给予spring boot应用的application.yml文件中的这样一个SPEL表达式--。
database:
schema: '#{"${ENV_VAR:}".equals("")?"DEMO":"DEMO_${ENV_VAR:}"}'
下面的代码中,如果${ENV_VAR} = XYZ,它就会打印出替代值,比如DEMO_XYZ DEMO。
@Value("${database.schema}")
private String schema;
但一个带有Table注释的Hibernate JPA实体无法将这里启用的SPEL变量作为模式--
@Entity
@Table(name = "TABLE_A", schema="${database.schema}") // prints whole spel expression here
public class TableA { ...
即使在下面,也不能使用默认模式的SPEL的替代值--------。
spring:
jpa:
show-sql: true
properties:
hibernate:
default_schema: ${database.schema} // prints whole value here as well
似乎flyway不能使用在application.yml中已经定义好的SPEL变量。
spring:
flyway:
jdbc-url: ...
schemas: ${database.schema}
有什么办法 hibernate.default_schema
和 flyway.schemas
接受SPEL表达式,如 ${database.schema}
在同一个YML文件中?
Spring Boot实际上不支持SpEL application.yml
.
如果你注射的是 Environment
和
String property = env.getProperty("database.schema");
你会看到占位符被解析了,但SpEL没有被解析。
@Value
必须有一些额外的逻辑来解决SpEL的进一步下游。
通过像下面这样以程序化的方式创建Hibernate JPA beans和Flyway beans来解决这个问题,而不是使用YML,因为只有@Value注解能够读取SPEL。
database:
schema: '#{"${ENV_VAR:}".equals("")?"DEMO":"DEMO_${ENV_VAR:}"}'
数据库配置
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = {"com.xyz"})
@EntityScan(basePackages = {"com.xyz"})
public class DbConfig
{
@Value("${database.schema}")
private String schema;
@Bean
public EntityManager entityManager(SessionFactory sessionFactory)
{
return sessionFactory.createEntityManager();
}
@Bean
public PlatformTransactionManager transactionManager()
{
return new JpaTransactionManager();
}
@Bean
public HikariConfig hikariConfig()
{
HikariConfig hikariConfig = new HikariConfig();
hikariConfig.setDriverClassName("net.client.jdbc.Driverx");
hikariConfig.setJdbcUrl(url);
Properties props = new Properties();
props.put("user", user);
props.put("password", password);
props.put("db", db);
props.put("schema", schema); // SCHEMA is from SPEL
hikariConfig.setDataSourceProperties(props);
return hikariConfig;
}
@Bean
public DataSource dataSource(HikariConfig hikariConfig)
{
HikariDataSource dataSource = new HikariDataSource(hikariConfig);
return dataSource;
}
@Bean
public LocalSessionFactoryBean entityManagerFactory(DataSource snowflakeDataSource)
{
LocalSessionFactoryBean localSessionFactoryBean = new LocalSessionFactoryBean();
localSessionFactoryBean.setDataSource(dataSource);
localSessionFactoryBean.setPackagesToScan("com.xyz");
Properties properties = new Properties();
properties.setProperty("hibernate.default_schema", schema);
properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
properties.setProperty("hibernate.show_sql", "true");
properties.setProperty("hibernate.format_sql", "true");
localSessionFactoryBean.setHibernateProperties(properties);
return localSessionFactoryBean;
}
飞航配置
@Value("${database.schema}")
private String schema;
@Bean
public Flyway flyway(DataSource dataSource)
{
Flyway flyWay = Flyway.configure()
.dataSource(dataSource)
.locations("classpath:/somefolder/migrations")
.schemas(schema) // SCHEMA is from SPEL
.baselineVersion("1.0")
.sqlMigrationPrefix("V")
.sqlMigrationSuffixes(".sql")
.placeholders(Map.of("key1", value1,
"key2", value2))
.placeholderReplacement(true)
.placeholderPrefix("%")
.placeholderSuffix("%")
.load();
flyWay.migrate();
return flyWay;
}