使用注释在Spring中自动装配

Question

在我简单的Spring项目中，我有一个名为Property的类bean：

@Component
public class Property implements DisposableBean,InitializingBean{

    private int square_area;
    private int floor_count;

    @Autowired
    @Qualifier("myLocation")
    private Location location;

    public Property() {
        super();
    }

    @Bean
    @Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)
    public Property prop(){
        return new Property(100,3);
    }

    public Property(int square_area, int floor_count, Location location) {
        this.square_area = square_area;
        this.floor_count = floor_count;
        this.location = location;
    }

    public Property(int square_area, int floor_count) {
        this.square_area = square_area;
        this.floor_count = floor_count;
        this.location = location;
    }


    public void afterPropertiesSet() throws Exception {
        // TODO Auto-generated method stub

    }

    public void destroy() throws Exception {
        // TODO Auto-generated method stub

    }

    public int getSquare_area() {
        return square_area;
    }

    public void setSquare_area(int square_area) {
        this.square_area = square_area;
    }

    public int getFloor_count() {
        return floor_count;
    }

    public void setFloor_count(int floor_count) {
        this.floor_count = floor_count;
    }


    public Location getLocation() {
        return location;
    }


    public void setLocation(Location location) {
        this.location = location;
    }

    @Override
    public String toString() {
        return "Property [square_area=" + square_area + ", floor_count=" + floor_count + ", location=" + location + "]";
    }

    public void gettingDusty(){
        System.out.println("Im getting dusty | " + this);
    }

}

我正在尝试自动装配字段“位置”。 位置类如下所示：

@Component
public class Location {

    private String country;
    private String region;
    private String settlement;
    private String street;
    private int house;

    @Bean("myLocation")
    @Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)
    public Location myLocation(){
        return new Location("US","California","Some peacefull town","Some peacefull street",1);
    }

    public Location(String country, String region, String settlement, String street, int house) {
        super();
        this.country = country;
        this.region = region;
        this.settlement = settlement;
        this.street = street;
        this.house = house;
    }

    @Override
    public String toString() {
        return "Location [country=" + country + ", region=" + region + ", settlement=" + settlement + ", street="
                + street + ", house=" + house + "]";
    }
}

我得到了org.springframework.beans.factory.UnsatisfiedDependencyException ：

Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'property': Unsatisfied dependency expressed through field 'location'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'location' defined in file [C:\Users\TheDanileron\spring_tests\spring_test4\target\classes\spring_tests\spring_test3\Location.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'java.lang.String' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:581)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:367)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1340)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:368)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1249)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1098)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:330)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1083)
    at spring_tests.spring_test3.App.main(App.java:25)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'location' defined in file [C:\Users\TheDanileron\spring_tests\spring_test4\target\classes\spring_tests\spring_test3\Location.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'java.lang.String' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:723)
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:192)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1269)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1126)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1133)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1060)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:578)
    ... 18 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'java.lang.String' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1501)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1099)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1060)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:809)
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:715)
    ... 31 more

如何使用Location.class中的myLocation方法创建的bean自动装配字段“location”？

Answer 1

@Component上有Location注释，因此Spring尝试使用需要参数的构造函数将其创建为bean。您的应用程序上下文不提供这些参数，因此bean创建失败。

您似乎只想配置Location programmaticaly的实例。然后从@Component中删除Location并创建一个单独的配置类，如LocationConfiguration：

@Configuration
public class LocationConfiguration {

    @Bean
    @Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)
    public Location myLocation(){
        return new Location("US","California","Some peacefull town","Some peacefull street",1);
    }
}