Working with multiple datasources and NamedParameterJdbcTemplate in Spring Boot 2.0.5
In this post I will illustrate how to use NamedParameterJdbcTemplate with multiple datasources in a Spring Boot 2.0.5 application. It expands on the spring guide available here.
1. Define the datasource properties
Add datasource properties to application.properties for each datasource to be configured.```
#db1 datasource
db1.datasource.jdbc-url=jdbc:mariadb://localhost/datasources_db1
db1.datasource.username=root
db1.datasource.password=
#db2 datasource
db2.datasource.jdbc-url=jdbc:mariadb://localhost/datasources_db2
db2.datasource.username=root
db2.datasource.password=
```Note that with Hikari on the classpath we need to replace the url property with jdbc-url as Hikari does not have a url property.
2. Configure the custom datasources
Add the following beans to a class annotated with @Configuration.```
@Bean
@Primary
@ConfigurationProperties(prefix = “db1.datasource”)
DataSource dataSourceOne() {
return DataSourceBuilder.create().build()
}
@Bean @ConfigurationProperties(prefix = “db2.datasource”) DataSource dataSourceTwo() { return DataSourceBuilder.create().build() }
@Bean NamedParameterJdbcTemplate namedParameterJdbcTemplateOne() { return new NamedParameterJdbcTemplate(dataSourceOne()) }
@Bean
NamedParameterJdbcTemplate namedParameterJdbcTemplateTwo() {
return new NamedParameterJdbcTemplate(dataSourceTwo())
}
```According do the guide, the @Primary annotation on one of the datasource beans should be put in for the various auto-configurations down the road that expect to get a datasource by type.
3. Use the defined beans
The NamedParemeterJdbcTemplate beans can then be autowired as follows:```
@Autowired
@Qualifier(“namedParameterJdbcTemplateOne”)
NamedParameterJdbcTemplate jdbcOne
@Autowired
@Qualifier(“namedParameterJdbcTemplateTwo”)
NamedParameterJdbcTemplate jdbcTwo
```Since by default @Autowire entries are resolved by type, the @Qualifier annotation is used to specify which of the two beans to use. Another approach would be to use the @Primary annotation on one of the defined beans. In that case, @Qualifier would only be needed when autowiring the other bean. An example project to illustrate the above is available on github.