NoSuchBeanDefinitionException: 沒有“int”類型的合格 bean

Question

我是 Spring 的完全初學者。

我現在正在嘗試查看是否可以測試 RequestMapping、RequestBody、RequestResponse 和 RestTemplate。

我想接收這個對象作為響應：

public interface TestObject {
    public int getId();
    public String getValue();
}

@Component
public class TestObjectImpl {

    private int id;
    private String value;

    public TestObjectImpl(int id, String value){
        this.id = id;
        this.value = value;
    }

    public int getId(){
        return id;
    }

    public String getValue(){
        return value;
    }
}

但是，我得到：

org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'int' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1486) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:189) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1193) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1095) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) ~[spring-beans-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.3.RELEASE.jar:1.5.3.RELEASE]
at io.yclub.castr.ads_java.ApplicationServer.main(ApplicationServer.java:12) [main/:na]

所以，它說，

Description:
Parameter 0 of constructor in io.yclub.castr.ads_java.google.adwords.model.TestObjectImpl required a bean of type 'int' that could not be found.

Action:
Consider defining a bean of type 'int' in your configuration.

但是我如何真正為'int'創建一個bean定義？

我做了什么？

// 編輯

感謝 KrishnaKuntala，這只是因為我沒有默認構造函數。

放置一個立即解決了問題。

Answer 1

您可以注入簡單的屬性，並且可以使用 @Value 注釋和占位符輕松訪問這些屬性：

@Component
public class TestObjectImpl {
    private int id;
    private String value;

    @Autowired
    public TestObjectImpl(@Value("${prop1}")int id, @Value("${prop2}")String value){
        this.id = id;
        this.value = value;
    }

    public int getId(){
        return id;
    }

    public String getValue(){
        return value;
    }
}

然后你需要將它們添加到 applicationContext 中：

<context:property-placeholder .../>

注意

如果您使用默認構造函數修復它，您將需要另一種機制來初始化您的 bean，因此，如果您想添加非 arg 構造函數而不是執行之前的構造，您必須知道自己在做什么。

Answer 2

您不需要只使用默認的無參數構造函數來創建 bean。 在你的情況下：

1) 如果您使用 XML 配置並希望使用接受參數的構造函數，則需要使用 constructor-arg 元素指定它們，如下所示：

<bean id="SomeObject" class="com.package.SomeObject">
  <constructor-arg val="someVal"/>
  <constructor-arg val="anotherVal"/>
</bean>

2) 如果您使用 Java 配置類，您將需要這樣的東西：

@Configuration
public class Config {
    @Bean
    public SomeObject someObject() {
        return new SomeObject(1, "default");
    }
}

看看這篇關於spring 構造函數注入的有用文章。

Answer 3

我正在使用 spring web-flow 並且該類沒有加載並且必須在 config servlet xml 中聲明。

Answer 4

請嘗試在您的 TestObjecImpl 類中添加一個默認值（無參數構造函數）。

@Component
public class TestObjectImpl {

    private int id;
    private String value;

    public TestObjectImpl(){
    }

    public TestObjectImpl(int id, String value){
        this.id = id;
        this.value = value;
    }

    public int getId(){
        return id;
    }

    public String getValue(){
        return value;
    }
}