[FIXED] Spring boot register an instance as a bean

Issue

I am trying to register Datasource instance as a bean in java code(spring-boot project)

Here is what I wrote. (This code is not working.)

@Configuration
public class DatabaseConfig {

    private Logger logger = Logger.getLogger(DatabaseConfig.class);

    @Autowired
    ApplicationContext context;

    private Map<String, Map<String, String>> dsMap;


    private Map<String, String> getTestDataSourceInfo () {
        Map<String, String> ds = new HashMap<String, String> ();
        ds.put("driverClassName", "com.mysql.jdbc.Driver");
        ds.put("url", "jdbc:mysql://123.456.78.912:3306/test");
        ds.put("username", "testuser");
        ds.put("password", "testuser");
        return ds;
    }

    public DatabaseConfig () {
        this.dsMap = new HashMap<String, Map<String, String>>();
        dsMap.put("sampleDs", getTestDataSourceInfo());
    }

    @PostConstruct
    public void loadDataSource () {

        logger.info("DS ================================ :: " +  String.valueOf(this.dsMap));
        this.dsMap.forEach((k,v) -> {

            logger.info("value ========================== :: " + String.valueOf(v));
            DataSource aSource = DataSourceBuilder.create()
                    .driverClassName(v.get("driverClassName"))
                    .url(v.get("url"))
                    .username(v.get("username"))
                    .password(v.get("password"))
                    .build();
            // PROBLEM STARTS ..............
            // Add datasource instance with name to context 

            context.getAutowireCapableBeanFactory().autowireBean(aSource);
        });
    }
}

Is there any proper way to register bean with an instance? I could not find any fine samples for this.

---

FYI, What I have expected in above code is...

• Spring boot application will read above class as a Configure
• It will make an Java instance in its constructor
• And it will add the instance as a bean to application context in loadDatasource method

However, it is not working. So I am curious about how to add an java instance as a bean to current Spring boot application context.

Solution

Actually, it could be more easier if I did not do this with DataSource.

Since, Spring-boot automatically do configure dataSource, I have to disable this settings first.

Here is what I did to achieve the goal

In @Configuration Class...

@Configuration
public class DatabaseConfig {

    private Logger logger = Logger.getLogger(DatabaseConfig.class);

    @Autowired
    ApplicationContext context;

    private Map<String, Map<String, String>> dsMap;


    private Map<String, String> getTestDataSourceInfo () {
        Map<String, String> ds = new HashMap<String, String> ();
        ds.put("driverClassName", "${ your driverClassName }");
        ds.put("url", "${ your url }");
        ds.put("username", "${ your user }");
        ds.put("password", "${ your password }");
        return ds;
    }

    public DatabaseConfig () {
        this.dsMap = new HashMap<String, Map<String, String>>();
        dsMap.put("sampleDs1", getTestDataSourceInfo());
        dsMap.put("sampleDs2", getTestDataSourceInfo());
    }

    @PostConstruct
    public void loadDataSource () {
        BeanDefinitionRegistry registry = (BeanDefinitionRegistry)  context.getAutowireCapableBeanFactory();
        this.dsMap.forEach((k,v) -> {

            BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(BasicDataSource.class);
            v.forEach((ds_key, ds_val) -> {
                builder.addPropertyValue(ds_key, ds_val);
            });
            BeanDefinition def = builder.getBeanDefinition();
            if(!registry.containsBeanDefinition(k)) registry.registerBeanDefinition(k, def);
        });
    }
}

In above class, I could add java instances to spring bean with BeanDefinitionRegistry and BeanDefinitionBuilder.

If this is just a bean, it would be end here, but what you are trying to add is DataSource bean, have to do some extra work.

Since, boot automatically setting DataSource, we have to disable that setting to register customized datasource.

In your @SpringbootApplication class, add @EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class}).

Now, you are able to user those bean in other beans via @Autowired and @Qualifier.

Thanks.

Answered By - Juneyoung Oh