Spring Boot - Auto wiring service having String constructor

how to autowire parameterized constructor in spring boot
how to autowire interface in spring boot
autowiring in spring boot
spring dependency injection annotation
autowiring in spring example byname
spring autowired constructor
@org.springframework.beans.factory.annotation.autowired(required=true) in spring boot
dependency injection in spring

How do i @autowire bean class TransactionManagerImpl which is having 1(String) argument constructor without using new in spring-boot application? Even after searching through many post i couldn't get any clue to autowire without using new

I need to autowire TransactionManager in three different classes and the parameters are different in all three classes.

This looks like very basic scenario.

@Service
public class TransactionManagerImpl implements TransactionManager {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    String txnLogFile;

    @ConstructorProperties({"txnLogFile"})
    public TransactionManagerImpl(String txnLogFile) {
        this.txnLogFile= txnLogFile; 
    }

}

is there any specific requirement where you want to use @Service annotation? if not then you can use @Bean to create a bean for TransactionManagerImpl like below.

@Configuration
public class Config {

@Value("${txnLogFile}")
private String txnLogFile;

@Bean
public TransactionManager transactionManager() {
    return new TransactionManagerImpl(txnLogFile);
 }

}

and remove @Service annotation from TransactionManagerImpl.

Guide to Spring @Autowired, If you have some solid experience in the Java ecosystem (6+ years), In this tutorial, we will look at how to enable autowiring, various ways to public String format() { The @Autowired annotation can also be used on constructors. course, focused on the fundamentals of Spring 5 and Spring Boot 2:. It calls the constructor having a large number of parameters. autodetect: In this mode, Spring first tries to autowire by the constructor. If this fails, it tries to autowire by using byType. 1.

Putting aside other complications, it can be done like this

public TransactionManagerImpl(@Value("${txnLogFile}") String txnLogFile) {
    this.txnLogFile= txnLogFile; 
}

Autowiring in Spring, So it can have a different property and bean name. It internally calls the setter method. constructor : The constructor mode injects the dependency� Spring container looks at the beans on which autowireattribute is set constructorin the XML configuration file. It then tries to match and wire its constructor's argument with exactly one of the beans name in the configuration file. If matches are found, it will inject those beans. Otherwise, bean(s) will not be wired.

Finally, i did it as below, now sure if this is the best way to do. I did not want to have three implementation just because of one variable.

application.yaml

app:
   type-a:
      txn-log-file: data/type-a-txn-info.csv
   type-b:
      txn-log-file: data/type-b-txn-info.csv
   default: 
      txn-log-file: data/default/txn-info.csv

MainApplication.java

@SpringBootApplication
public class MainApplication {

    public static void main(String[] args) {
        new SpringApplicationBuilder(MainApplication.class).web(WebApplicationType.NONE).run(args);
    }

    @Bean
    public TransactionManager transactionManager(@Value("${app.default.txn-log-file}") String txnLogFile) {
        return new TransactionManagerImpl(txnLogFile);
    }

    @Bean
    public CsvService csvService(String txnLogFile) {
        return new CsvServiceImpl(txnLogFile);
    }
}

TypeOneRoute.java

@Configuration
public class TypeOneRoute extends RouteBuilder {

    @Value("${app.type-a.txn-log-file}")
    private String txnLogFile;

    @Autowired
    private ApplicationContext applicationContext;

    private TransactionManager transactionManager;

    @Override
    public void configure() throws Exception {
        transactionManager = applicationContext.getBean(TransactionManager.class, txnLogFile);
        transactionManager.someOperation();

    }
}

TypeTwoRoute.java

@Configuration
public class TypeTwoRoute extends RouteBuilder {

    @Value("${app.type-b.txn-log-file}")
    private String txnLogFile;

    @Autowired
    private ApplicationContext applicationContext;

    private TransactionManager transactionManager;

    @Override
    public void configure() throws Exception {
        transactionManager = applicationContext.getBean(TransactionManager.class, txnLogFile);
        transactionManager.create();

    }
}

TransactionManager.java

@Service
@Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)
public interface TransactionManager {

    public ZonedDateTime create() throws IOException, ParseException;

}

TransactionManagerImpl.java

public class TransactionManagerImpl implements TransactionManager {

    @Autowired
    private ApplicationContext applicationContext;

    private String txnLogFile;

    public TransactionManagerImpl(String txnLogFile) {
        this.txnLogFile = txnLogFile;
    }

    private CsvService csvService;

    @PostConstruct
    public void init() {
        csvService = applicationContext.getBean(CsvService.class, txnLogFile);
    }

    public ZonedDateTime create() throws IOException, ParseException {
        try {
            csvService.createTxnInfoFile();
            return csvService.getLastSuccessfulTxnTimestamp();
        } catch (IOException e) {
            throw new IOException("Exception occured in getTxnStartDate()", e);
        }
    }

}

Initially TransactionManager Bean will be registered with the app.default.txn-info.csv and when i actually get it from ApplicationContext i am replacing the value with the parameter passed to get the bean from ApplicationContext

Autowiring In Spring, It calls the constructor having large number of parameters. Autowiring by autodetect uses two modes i.e. constructor or byType modes @ SpringBootApplication public class AutowiringdemoApplication Autowired; public class Employee { private int eid; private String Service Locator Pattern in Spring. Spring bean auto-wiring modes; Spring auto-wiring mode byName; Spring auto-wiring mode byType; Spring auto-wiring mode constructor; Spring auto-wiring using @Autowired annotation example; Spring auto-wiring using @Qualifier annotation example; Spring log4j configuration; How to schedule jobs using @Scheduled annotation in spring? Send E-mail

Best Practices for Dependency Injection with Spring, For our purposes, the service has one method that returns a string. When using a constructor to set injected properties, you do not have to provide the autowire annotation. Annotation of constructors for dependency injection has been Spring Boot Web Application - Part 4 - Spring MVCSeptember 10,� Spring bean autowire by constructor Last Updated On October 14, 2019 In Spring framework, bean autowiring by constructor is similar to byType, but applies to constructor arguments. In autowire enabled bean, it look for class type of constructor arguments, and then do a autowire by type on all constructor arguments.

Core Technologies - Project Metadata API Guide, It can be useful to have bean definitions span multiple XML files. Often use configured instance List<String> userList = service. With byType or constructor autowiring mode, you can wire arrays and typed collections. If you access scoped beans within Spring Web MVC, in effect, within a request that is� Spring expects @Autowired dependencies to be available when the dependent bean is being constructed. If the framework cannot resolve a bean for wiring, it will throw the below-quoted exception and prevent the Spring container from launching successfully:

Spring Autowiring by Constructor, Spring Autowiring by Constructor - This mode is very similar to byType, but it Spring - Transaction Management � Spring - Web MVC Framework � Spring Let us have a working Eclipse IDE in place and take the following steps to private String name; public TextEditor( SpellChecker spellChecker, String name ) { this. Spring auto-wiring mode byName. In spring, auto-wiring by name means autowiring by property name. This option will inspect the container and look for a bean named exactly the same as the property which needs to be autowired.

Comments
  • Where txnLogFile comes from? This will create singleton instance anyway. If you have 3 different implementaitons you will have to use @Qualifier to distinct them. You can always use ApplicationContext to get whay you need and provide contrctor args there. Also you can use @Bean with qualifier like in answer.
  • txnLogFile comes from properties file. And there are three different log files. Depending on the three diff transactions i will be injecting taxLogFile to transactionManager which will write to txnLogFile
  • You can also use @Value directly on contructor argument.
  • @Antoniossss that will read only single value, so i have to have three impl of TransactionManager
  • Yep, that is why you have to either distinct those values per implementation or get beans from application context providing required string as arg. In both cases, qualifier is needed.