Micronaut：从上下文中获取 bean 的问题

Question

我有一个 class，其中包含注入和强制（最终）字段。对于常见的情况，我可以使用 MicronautBeanFactory.getBean(type) 或 BeanContext.getBean(type) 从上下文中获取 bean，但在这种情况下，我必须传递类型和参数。

我为此创建了简单的测试

@MicronautTest
public class ETLExecutorTest {

    @Inject
    private MicronautBeanFactory micronautBeanFactory;

    @Test
    void testGetBean() {
        Object[] args = new Object[] {"name", "spec", 1L};
        ObjectInstance instance = micronautBeanFactory.getBean(ObjectInstance.class, args);
    }
}

对象（bean）代码

@Prototype
public class ObjectInstance {

    @Inject
    private ObjectStorage objectStorage;

    private final String name;
    private final String spec;
    private final Long id;

    public ObjectInstance(String name, String spec, Long id) {
        this.name = name;
        this.spec = spec;
        this.id = id;
    }
}

当我运行收到异常时

io.micronaut.context.exceptions.DependencyInjectionException: Failed to inject value for parameter [name] of class: com.ObjectInstance Message: Multiple possible bean candidates found: [java.lang.String, java.lang.String, java.lang.String] Path Taken: new ObjectInstance([String name],String specName,Long accountId) at io.micronaut.context.AbstractBeanDefinition.getBeanForConstructorArgument(AbstractBeanDefinition.java:1016) at com.$TableInstanceDefinition.build(Unknown Source) at io.micronaut.context.DefaultBeanContext.doCreateBean(DefaultBeanContext.java:1598) at io.micronaut.context.DefaultBeanContext.getScopedBeanForDefinition(DefaultBeanContext.java:2076) at io.micronaut.context.DefaultBeanContext.getBeanForDefinition(DefaultBeanContext.java:1991) at io.micronaut.context.DefaultBeanContext.getBeanInternal(DefaultBeanContext.java:1963) at io.micronaut.context.DefaultBeanContext.getBean(DefaultBeanContext.java:610) at io.micronaut.spring.context.factory.MicronautBeanFactory.getBean(MicronautBeanFactory.java:264) Caused by: io.micronaut.context.exceptions.NonUniqueBeanException: Multiple possible bean candidates found: [java.lang.String, java.lang.String, java.lang.String] at io.micronaut.context.DefaultBeanContext.findConcreteCandidate(DefaultBeanContext.java:1701) at io.micronaut.context.DefaultApplicationContext.findConcreteCandidate(DefaultApplicationContext.java:395) at io.micronaut.context.DefaultBeanContext.lastChanceResolve(DefaultBeanContext.java:2289) at io.micronaut.context.DefaultBeanContext.findConcreteCandidateNoCache(DefaultBeanContext.java:2212) at io.micronaut.context.DefaultBeanContext.lambda$findConcreteCandidate(DefaultBeanContext.java:2155) at io.micronaut.core.util.clhm.ConcurrentLinkedHashMap.lambda$compute[=13=](ConcurrentLinkedHashMap.java:721) at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660) at io.micronaut.core.util.clhm.ConcurrentLinkedHashMap.compute(ConcurrentLinkedHashMap.java:733) at io.micronaut.core.util.clhm.ConcurrentLinkedHashMap.computeIfAbsent(ConcurrentLinkedHashMap.java:710) at io.micronaut.context.DefaultBeanContext.findConcreteCandidate(DefaultBeanContext.java:2154) at io.micronaut.context.DefaultBeanContext.getBeanInternal(DefaultBeanContext.java:1943) at io.micronaut.context.DefaultBeanContext.getBean(DefaultBeanContext.java:1082) at io.micronaut.context.AbstractBeanDefinition.getBeanForConstructorArgument(AbstractBeanDefinition.java:1007)

我也尝试做另一个测试，但在这种情况下，我收到了没有注入字段的对象

@MicronautTest
public class ETLExecutorTest {

    @Inject
    private BeanContext beanContext;

    @Test
    void testGetBean() {
        Object[] args = new Object[] {"name", "spec", 1L};
        BeanDefinition<ObjectInstance> definition = beanContext.getBeanDefinition(ObjectInstance.class);
        ObjectInstance instance =  definition.getConstructor().invoke(args); // there are no injections here: ObjectStorage of instance = null.
    }
}

你能告诉我，我做错了什么吗？？？

Answer 1

micronaut 试图通过 构造函数 创建 bean ObjectInstance 但找不到要注入的 String name ，看起来它只是一个ObjectInstance 的简单字段，在本例中，它按预期工作：

io.micronaut.context.exceptions.DependencyInjectionException: Failed to inject value for parameter [name]

如果你添加一个默认构造函数，那么ObjectInstance将被创建，你可以通过beanContext.getBean(ObjectInstance.class):

获取bean

@Prototype
public class ObjectInstance {

    @Inject
    private ObjectStorage objectStorage;

    private String name;
    private String spec;
    private Long id;


    public ObjectInstance() {}

    public ObjectInstance(String name, String spec, Long id) {
        this.name = name;
        this.spec = spec;
        this.id = id;
    }

}

另外注意MicronautBeanFactory implements ListableBeanFactory，这个是为了和Spring整合

P.S。我建议您更改代码结构，POJO 不应包含 beans

Micronaut：从上下文中获取 bean 的问题

Micronaut: problem with getting bean from context

java

dependency-injection

micronaut