Question

我有一些像这样的代码：

package beans;

public interface Pet {
    public String speak();
}

package beans;

public class Cat implements Pet {

    private int age;

    public Cat(int age) {
        this.age = age;
    }

    @Override
    public String speak() {
        return "meaow";
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

package springlearning;

import beans.*;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Bean;

@Configuration
public class ProjectConfiguration {

    @Bean
    public Pet cat(int age) {
        return new Cat(age);
    }
}

package springlearning;

import beans.*;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {

public static void main(String[] args) {
    AnnotationConfigApplicationContext context = 
            new AnnotationConfigApplicationContext(ProjectConfiguration.class);
    Cat cat = (Cat)context.getBean("cat", 3);//here i have my error
    System.out.println(cat.getAge());
    Person brajan = (Person)context.getBean("brajan");
    System.out.println(brajan);
}

}

这是我的堆栈跟踪：

WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cat' defined in springlearning.ProjectConfiguration: Unsatisfied dependency expressed through constructor argument with index 0 of type [int]: : No qualifying bean of type [int] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [int] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cat' defined in springlearning.ProjectConfiguration: Unsatisfied dependency expressed through constructor argument with index 0 of type [int]: : No qualifying bean of type [int] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [int] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:749)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:464)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1123)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1018)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510)
    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:839)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init>(AnnotationConfigApplicationContext.java:84)
    at springlearning.Main.main(Main.java:9)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [int] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1373)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1119)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:813)
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741)
    ... 14 more

有人可以向我解释它是如何运作的，因为我一直在寻找答案而且没有任何结果。我的想法是拥有bean，我可以在调用它时传递一个值。我也试过这样的事情：

@Bean
public Pet cat() {
    return new Cat(0);
}

@Bean
public Pet cat(int age) {
    Cat c = (Cat)appContext.getBean("cat");
    c.setAge(age);
    return c;
}

请帮助：）

Answer 1

按如下方式定义您的cat bean：

@Bean
@Scope("prototype")
public Pet cat(int age) {
    return new Cat(age);
}

如果传递构造函数params，那么bean必须是原型而不是单例。

面向Spring Java的配置getBean（），参数不起作用

1 个答案: