Spring Framework

public class HelloWorldServiceClient {

    @Autowired
    private HelloWorldService helloWorld;

    public void showMessage() {
        helloWorld.sayHi("Hello world!");
    }
}

Original Post

public class UserRegistrationBeanImpl implements UserRegistrationBean {

    @Autowired
    private RegistrationService registrationService;
    @Autowired
    private UserRegistrationValidator validator;

    private UserInfo userInfo;

    @PostConstruct
    private void initialize () {
        System.out.println("initializing: " + System.identityHashCode(this));
    }

    @Override
    public void setUserInfo (UserInfo userInfo) {
        this.userInfo = userInfo;
    }

    @Override
    public Map<String, String> validate () {
        if (userInfo == null) {
            throw new RuntimeException("UserInfo must be set before calling validate method");
        }

        Map<String, String> errors = new LinkedHashMap<>();

        String errorMessage = validator.validateEmail(userInfo.getEmail());
        if (errorMessage != null) {
            errors.put(KEY_EMAIL, errorMessage);
        }

        errorMessage = validator.validatePassword(userInfo.getPassword());
        if (errorMessage != null) {
            errors.put(KEY_PASSWORD, errorMessage);
        }

        return errors;
    }

    @Override
    public void register () {
        registrationService.register(userInfo);
    }
}

Original Post

Using @Autowired at field.

public class OrderServiceClient {

    @Autowired
    @Qualifier("OrderServiceA")
    private OrderService orderService;

    public void showPendingOrderDetails () {
        for (String orderId : Arrays.asList("100", "200", "300")) {
            System.out.println(orderService.getOrderDetails(orderId));
        }
    }
}

Original Post

    private static class OrderServiceClient {

        private OrderService orderService;

        @Autowired
        public void setOrderService(OrderService orderService) {
            this.orderService = orderService;
        }

        public void showPendingOrderDetails() {
            System.out.println(orderService.getOrderDetails("200"));
        }
    }

Original Post

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
@Configuration
public class AppConfig {

    @Bean(autowire = Autowire.BY_TYPE)
    public OrderService orderService() {
        return new OrderService();
    }

    @Bean
    public Dao daoA() {
        return new DaoA();
    }

    @Primary
    @Bean
    public Dao daoB() {
        return new DaoB();
    }

    public static void main(String[] args) throws InterruptedException {
        AnnotationConfigApplicationContext context =
                new AnnotationConfigApplicationContext(AppConfig.class);

        OrderService orderService = context.getBean(OrderService.class);
        orderService.placeOrder("122");

    }
}

Original Post

This example demonstrates how @Autowired annotation is used to throw NoSuchBeanDefinitionException. By default @Autowired(required=true) which means the annotated injection point must be set with the dependency.

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class AutowiredExample {

    @Bean
    public ClientBean clientBean () {
        return new ClientBean();
    }

    //remove following comment to fix java.lang.IllegalArgumentException: ServiceBean not set
  /*  @Bean
    public ServiceBean serviceBean () {
        return new ServiceBean();
    }*/

    public static void main (String... strings) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
                            AutowiredExample.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.work();

    }

    public static class ClientBean {
        private ServiceBean serviceBean;

        @Autowired
        public void setServiceBean (ServiceBean serviceBean) {
            this.serviceBean = serviceBean;
        }

        public void work () {
            System.out.println("service bean instance: " + serviceBean);
        }

    }

    public static class ServiceBean {
    }
}

Original Post

Using Autowire.NO mode.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class AutowireNoExample {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.NO)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean () {
            return new ServiceBean("Service bean 1");
        }
    }

    private static class ClientBean {
        @Autowired
        private ServiceBean serviceBean;

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service bean 1

Original Post

Using Autowire.NO mode. This example shows that in Autowire.NO mode too (in fact, in all autowiring modes), Spring framework first tries to match by name. If there's no match by 'name' then it falls back to matching by type approach. Try to change autowire = Autowire.NO to autowire = Autowire.BY_TYPE on clientBean() method, we will still have a successful match by 'name'.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;

public class AutowireNoExample2 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    public static class Config {

        @Bean(autowire = Autowire.NO)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service Bean 1");
        }

        @Bean
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service Bean 2");
        }
    }

    private static class ClientBean {
        @Autowired
        private ServiceBean serviceBean;

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'clientBean': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.logicbig.example.AutowireNoExample2$ServiceBean com.logicbig.example.AutowireNoExample2$ClientBean.serviceBean; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.logicbig.example.AutowireNoExample2$ServiceBean] is defined: expected single matching bean but found 2: serviceBean2,serviceBean1
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues (AutowiredAnnotationBeanPostProcessor.java:334)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean (AbstractAutowireCapableBeanFactory.java:1214)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean (AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean (AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject (AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton (DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean (AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean (AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons (DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization (AbstractApplicationContext.java:838)
    at org.springframework.context.support.AbstractApplicationContext.refresh (AbstractApplicationContext.java:537)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init> (AnnotationConfigApplicationContext.java:84)
    at com.logicbig.example.AutowireNoExample2.main (AutowireNoExample2.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
    at java.lang.Thread.run (Thread.java:748)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.logicbig.example.AutowireNoExample2$ServiceBean com.logicbig.example.AutowireNoExample2$ClientBean.serviceBean; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.logicbig.example.AutowireNoExample2$ServiceBean] is defined: expected single matching bean but found 2: serviceBean2,serviceBean1
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject (AutowiredAnnotationBeanPostProcessor.java:573)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject (InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues (AutowiredAnnotationBeanPostProcessor.java:331)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean (AbstractAutowireCapableBeanFactory.java:1214)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean (AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean (AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject (AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton (DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean (AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean (AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons (DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization (AbstractApplicationContext.java:838)
    at org.springframework.context.support.AbstractApplicationContext.refresh (AbstractApplicationContext.java:537)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init> (AnnotationConfigApplicationContext.java:84)
    at com.logicbig.example.AutowireNoExample2.main (AutowireNoExample2.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
    at java.lang.Thread.run (Thread.java:748)
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.logicbig.example.AutowireNoExample2$ServiceBean] is defined: expected single matching bean but found 2: serviceBean2,serviceBean1
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency (DefaultListableBeanFactory.java:1126)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency (DefaultListableBeanFactory.java:1014)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject (AutowiredAnnotationBeanPostProcessor.java:545)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject (InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues (AutowiredAnnotationBeanPostProcessor.java:331)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean (AbstractAutowireCapableBeanFactory.java:1214)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean (AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean (AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject (AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton (DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean (AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean (AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons (DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization (AbstractApplicationContext.java:838)
    at org.springframework.context.support.AbstractApplicationContext.refresh (AbstractApplicationContext.java:537)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init> (AnnotationConfigApplicationContext.java:84)
    at com.logicbig.example.AutowireNoExample2.main (AutowireNoExample2.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
    at java.lang.Thread.run (Thread.java:748)

Original Post

Using autowiring mode Autowire.BY_TYPE. We don't need to use @Autowired. There should be only one injection point matching the same type otherwise we will have NoUniqueBeanDefinitionException

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class AutowireByType {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_TYPE)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service bean 1");
        }
    }

    private static class ClientBean {
        private ServiceBean serviceBean;

        public void setServiceBean (ServiceBean serviceBean) {
            this.serviceBean = serviceBean;
        }

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service bean 1

Original Post

Using autowiring mode Autowire.BY_NAME. We need to use @Autowired at the injection point.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class AutowireByName {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_NAME)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service bean 1");
        }

        @Bean
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service bean 2");
        }
    }

    private static class ClientBean {
        @Autowired
        private ServiceBean serviceBean1;

        public void doSomething () {
            System.out.println(serviceBean1.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service bean 1

Original Post

Using autowiring mode Autowire.BY_NAME.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * In this example we are explicitly giving the bean a name by using @Bean(name =....)
 */
public class AutowireByName2 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_NAME)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean(name = "someOtherServiceBean")
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service bean 1");
        }

        @Bean
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service bean 2");
        }
    }

    private static class ClientBean {
        private ServiceBean someOtherServiceBean;

        @Autowired
        public void setSomeOtherServiceBean (ServiceBean serviceBean) {
            this.someOtherServiceBean = serviceBean;
        }

        public void doSomething () {
            System.out.println(someOtherServiceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service bean 1

Original Post

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;

public class AutowireNoExample3 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    public static class Config {

        @Bean(autowire = Autowire.NO)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service Bean 1");
        }

        @Bean
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service Bean 2");
        }
    }

    private static class ClientBean {
        @Autowired
        private ServiceBean serviceBean2;

        public void doSomething () {
            System.out.println(serviceBean2.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service Bean 2

Original Post

Using autowiring mode Autowire.BY_TYPE and @Qualifier.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class AutowireByType2 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_TYPE)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean () {
            return new ServiceBean("Service bean 1");
        }

        @Bean
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service bean 2");
        }
    }

    private static class ClientBean {
        private ServiceBean serviceBean;

        public void setServiceBean (@Qualifier("serviceBean2") ServiceBean serviceBean) {
            this.serviceBean = serviceBean;
        }

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Original Post

Using autowiring mode Autowire.BY_TYPE and @Qualifier (at bean declaration and injection point).

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class AutowireByType3 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_TYPE)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean () {
            return new ServiceBean("Service bean 1");
        }

        @Bean
        @Qualifier("myService")
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service bean 2");
        }
    }

    private static class ClientBean {
        private ServiceBean serviceBean;

        public void setServiceBean (@Qualifier("myService") ServiceBean serviceBean) {
            this.serviceBean = serviceBean;
        }

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Original Post

Using autowiring mode Autowire.BY_NAME.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * In this example we are explicitly giving the bean a name by using @Bean(name =....)
 */
public class AutowireByName3 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_NAME)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service bean 1");
        }

        @Bean(name = "myService")
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service bean 2");
        }
    }

    private static class ClientBean {
        private ServiceBean serviceBean;

        @Autowired
        @Qualifier("myService")
        public void setServiceBean(ServiceBean serviceBean) {
            this.serviceBean = serviceBean;
        }

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service bean 2

Original Post

Using autowiring mode Autowire.BY_NAME.

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * In this example we are explicitly giving the bean a name by using @Bean(name =....)
 */
public class AutowireByName4 {

    public static void main (String[] args) {
        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

    @Configuration
    public static class Config {

        @Bean(autowire = Autowire.BY_NAME)
        public ClientBean clientBean () {
            return new ClientBean();
        }

        @Bean
        public ServiceBean serviceBean1 () {
            return new ServiceBean("Service bean 1");
        }

        @Bean
        @Qualifier("myService")
        public ServiceBean serviceBean2 () {
            return new ServiceBean("Service bean 2");
        }
    }

    private static class ClientBean {
        private ServiceBean serviceBean;

        @Autowired
        @Qualifier("myService")
        public void setServiceBean(ServiceBean serviceBean) {
            this.serviceBean = serviceBean;
        }

        public void doSomething () {
            System.out.println(serviceBean.getMsg());
        }
    }

    private static class ServiceBean {
        private String msg;

        public ServiceBean (String msg) {
            this.msg = msg;
        }

        public String getMsg () {
            return msg;
        }
    }
}

Output

Service bean 2

Original Post

import org.springframework.beans.factory.annotation.Autowired;

public class Greeter {
    @Autowired
    private GreetingService greetingService;

    public void showGreeting(String name) {
        System.out.println(greetingService.getGreeting(name));
    }
}

Original Post

import org.springframework.beans.factory.annotation.Autowired;

public class Greeter {

    private GreetingService greetingService;

    @Autowired
    public void setGreetingService(GreetingService greetingService) {
        this.greetingService = greetingService;
    }

    public void showGreeting(String name){
        System.out.println(greetingService.getGreeting(name));
    }
}

@Autowired can be used on any arbitrary method, having multiple parameters:

import org.springframework.beans.factory.annotation.Autowired;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class Greeter {
    private String greetingFormat;

    @Autowired
    public void configure(GreetingService greetingService, LocalDateTime appStartTime) {
        greetingFormat = String.format("%s. This app is running since: %s%n", greetingService.getGreeting("<NAME>"),
                appStartTime.format(DateTimeFormatter.ofPattern("YYYY-MMM-d")));
    }

    public void showGreeting(String name) {
        System.out.printf(greetingFormat.replaceAll("<NAME>", name));
    }
}

Original Post

    @Component
    public static class OrderServiceClient {

        private OrderService orderService;

        @Autowired
        OrderServiceClient(OrderService orderService) {
            this.orderService = orderService;
        }

        public void showPendingOrderDetails() {
            System.out.println(orderService.getOrderDetails("500"));
        }
    }

Original Post

Spring Framework - @Autowired Examples

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See Also