multiple data source in spring boot - jdbcTemplate is null

Question

I am using multiple data sources in my spring boot project as,

application.properties

#first DB integration.datasource.jdbc-url=jdbc:sqlserver://localhost:port1/my_sample_schema1 integration.datasource.username=username integration.datasource.password=password integration.datasource.driver-class-name=com.microsoft.sqlserver.jdbc.SQLServerDriver integration.jpa.database-platform=org.hibernate.dialect.SQLServer2012Dialect integration.jpa.show-sql=true #second DB spring.datasource.jdbc-url=jdbc:sqlserver://localhost:port2/my_sample_schema2 spring.datasource.username=username spring.datasource.password=password spring.datasource.driver-class-name=com.microsoft.sqlserver.jdbc.SQLServerDriver spring.datasource.platform=org.hibernate.dialect.SQLServer2012Dialect spring.jpa.show-sql=true

DBConfig.java

@Configuration public class DBConfig { @Primary @Bean(name = "integrationDataSource") @ConfigurationProperties(prefix = "integration.datasource") public DataSource integrationDataSource() { return DataSourceBuilder.create().build(); } @Bean(name = "mainDataSource") @ConfigurationProperties(prefix = "spring.datasource") public DataSource mainDataSource() { return DataSourceBuilder.create().build(); } @Primary @Autowired @Bean(name = "integrationJdbcTemplate") public JdbcTemplate integrationJdbcTemplate(@Qualifier("integrationDataSource") DataSource integrationDataSource) { return new JdbcTemplate(integrationDataSource); } @Bean(name ="mainJdbcTemplate") @Autowired public JdbcTemplate mainJdbcTemplate(@Qualifier("mainDataSource") DataSource mainDataSource) { return new JdbcTemplate(mainDataSource); } }

SampleClass.java

@Slf4j @Component public class SampleClass{ @Autowired private JdbcTemplate mainJdbcTemplate; @Autowired @Qualifier("integrationJdbcTemplate") private static JdbcTemplate integrationTemplate; public static final String SELECT_QUERY = "select * from tableA"; public List<SampleDto> getDBData(SampleDto fileData) { List<SampleDto> data = null; try { data = integrationTemplate.query( SampleClass.SELECT_QUERY, new Object[] { param1, param2 }, new SampleDataMapper()); } catch (DataAccessException e) { log.error(e.getMessage(), e); } return data; } }

In the SampleClass.java am getting integrationTemplate as null . Why is this so? mainJdbcTemplate is working. But integrationTemplate is getting as null and not able to excute the query.

Try without the @Qualifier and with the exact same name as the defined @Bean (integrationJdbcTemplate) UPDATE, you can't use a static field with @Autowired — Aris
– Aris, Commented Oct 22, 2021 at 8:22

Aris · Accepted Answer · 2021-10-22 08:42:53Z

The issue is that you have a static field with @Autowired

With @Autowired fields are injected right after the construction of a bean, before any config methods are invoked. Read here for more information about Ioc and Bean injection.

Remove the static:

@Autowired @Qualifier("integrationJdbcTemplate") private JdbcTemplate integrationTemplate;

Of course, you can do this but it's not recommended:

private static JdbcTemplate integrationTemplate; @Autowired public void setIntegrationJdbcTemplate(JdbcTemplate integrationTemplate){ SampleClass.integrationTemplate = integrationTemplate; }

Autowiring by Name

If you use the exact same name as the one that you used for the bean initialization you don't need to put the @Qualifier, just use as:

@Autowired private JdbcTemplate integrationJdbcTemplate;

And that's because Spring knows which bean to inject. If you have more beans of the same type then it will throw NoUniqueBeanDefinitionException then you define it with the @Qualifier.

I would also suggest marking your fields as final, just for good practices.

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