最简单的Spring Demo(基于maven)

• 演示效果

创建PersonService的接口和实现类，创建WeatherService的接口和实现类，PersionService实现类依赖WeatherService，PersonService有goToSchool的接口，实现这个接口的实现会调用WeatherService的ifRain，如果不会下雨就输出去上学，创建ApplicationContext容器，并且通过该容器获取person实现类的bean，并且调用goToSchool方法。

• 引入相关包

    
        4.0.2.RELEASE
    

    
        
            org.springframework
            spring-context
            ${springframework.version}
        
    

在pom文件中添加dependency。本文只需要引入spring-context的包，spring-context包已经依赖了spring-core和spring-beans的包。

• 使用xml的配置方式

Java

public interface WeatherService {
    boolean ifRain();
}

public class WeatherServiceImpl implements WeatherService{
    @Override
    public boolean ifRain() {
        return false;
    }
}

public interface PersonService {
    void goToSchool(String name);
}

public class PersonServiceImpl implements PersonService {

    private WeatherService weatherService;
    //在这里需要set，否则xml中无法注入
    public void setWeatherService(WeatherService weatherService) {
        this.weatherService = weatherService;
    }

    @Override
    public void goToSchool(String name) {
        if (weatherService.ifRain()) {
            System.out.println("because rain");
            return;
        }
        System.out.println(name + " go to school");
    }
}

applicationContext.xml 配置文件

    
   <！-- 在 personService中注入weatherService -->
    
        
    

测试

    public static void main(String[] args) {
        //创建容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取personService的bean
        PersonService personService = (PersonService)applicationContext.getBean("personService");
        //调用方法
        personService.goToSchool("huang");
    }

• 使用xml + 注解的方式

Java

public interface WeatherService {
    boolean ifRain();
}
@Service("weatherService")
public class WeatherServiceImpl implements WeatherService{

    @Override
    public boolean ifRain() {
        return false;
    }
}
public interface PersonService {
    void goToSchool(String name);
}
@Service("personService")
public class PersonServiceImpl implements PersonService {

    @Resource
    private WeatherService weatherService;

    @Override
    public void goToSchool(String name) {
        if (weatherService.ifRain()) {
            System.out.println("because rain");
            return;
        }
        System.out.println(name + " go to school");
    }
}

applicationContext.xml 配置文件

测试

    public static void main(String[] args) {
        //创建容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取personService的bean
        PersonService personService = (PersonService)applicationContext.getBean("personService");
        //调用方法
        personService.goToSchool("huang");
    }

• 使用纯注解

Java

public interface WeatherService {
    boolean ifRain();
}

public class WeatherServiceImpl implements WeatherService{
    @Override
    public boolean ifRain() {
        return false;
    }
}

public interface PersonService {
    void goToSchool(String name);
}

public class PersonServiceImpl implements PersonService {

    private WeatherService weatherService;
    //在这里需要set，否则xml中无法注入
    public void setWeatherService(WeatherService weatherService) {
        this.weatherService = weatherService;
    }

    @Override
    public void goToSchool(String name) {
        if (weatherService.ifRain()) {
            System.out.println("because rain");
            return;
        }
        System.out.println(name + " go to school");
    }
}

@Configuration
public class BeanConfig {

    @Bean(name = "personService")
    public PersonService personService() {
        PersonServiceImpl personService = new PersonServiceImpl();
        personService.setWeatherService(weatherService());
        return personService;
    }

    @Bean(name = "weatherService")
    public WeatherService weatherService() {
        return new WeatherServiceImpl();
    }
}

测试

    public static void main(String[] args) {
        //创建容器
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);
        //获取personService的bean
        PersonService personService = (PersonService)applicationContext.getBean("personService");
        //调用方法
        personService.goToSchool("huang");
    }