Spring：找不到默认构造函数

Question

我的英语不完美甚至不错，但我会尝试解释我的问题。

我需要在我的应用程序REST客户端编写，它使用Wiki API来获取一些必要的数据。我不知道这段代码有什么问题。

这是我的客户：

@Component("wikiService")
public class WikiServiceImpl implements WikiService {

private Log log = LogFactory.getLog(WikiServiceImpl.class);

private String wikiBaseURL = "http://pl.wikipedia.org/w/api.php?action=query&prop=revisions&titles={name}&rvprop=content&";

private final RestTemplate restTemplate;

public WikiServiceImpl() {
    restTemplate = new RestTemplate();
}

@Autowired
public WikiServiceImpl(RestTemplate restTemplate) {
    this.restTemplate = restTemplate;
}
// other metods ommited

控制器：

@Controller
@RequestMapping(value="/ask")
public class WikiController {

    final Logger logger= LoggerFactory.getLogger(WikiController.class);

    @Autowired
    private WikiService wikiService;

    @RequestMapping(value="/{query}", method=RequestMethod.GET)
    @ResponseBody
    public String getAnswer(@PathVariable String query) {
        logger.info("Odebralem zapytanie: " + query);
        String bDate = wikiService.getBirthDate(query);
        logger.info("Znaleziona data: " + bDate);
        return bDate;
    }

    public final WikiService getWikiService() {
        return wikiService;
    }

    public final void setWikiService(WikiService wikiService) {
        this.wikiService = wikiService;
    }
}

这是rest servlet context：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:oxm="http://www.springframework.org/schema/oxm"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.1.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
        http://www.springframework.org/schema/oxm
        http://www.springframework.org/schema/oxm/spring-oxm.xsd">

    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
                <property name="marshaller" ref="castorMarshaller"/>
                <property name="unmarshaller" ref="castorMarshaller"/>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

    <context:annotation-config/>
    <context:component-scan base-package="com.web.restful.controller"/>

    <bean id="castorMarshaller" class="org.springframework.oxm.castor.CastorMarshaller">
        <property name="mappingLocation" value="classpath:oxm-mapping.xml"/>
    </bean>
</beans>

Root context：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/jdbc
        http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.1.xsd">

    <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

    <jdbc:embedded-database id="dataSource" type="H2">
        <jdbc:script location="classpath:META-INF/schema.sql"/>
        <jdbc:script location="classpath:META-INF/test-data.sql"/>
    </jdbc:embedded-database>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="emf"/>
    </bean>

    <tx:annotation-driven transaction-manager="transactionManager" />

    <context:annotation-config/>
    <context:component-scan base-package="com.service.jpa, com.wiki.service" />

    <bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
        </property>
        <property name="packagesToScan" value="com.kr.soft.domain"/>
        <property name="jpaProperties">
        <props>
            <prop key="hibernate.dialect"> 
                org.hibernate.dialect.H2Dialect
            </prop>
            <prop key="hibernate.max_fetch_depth">3</prop>
            <prop key="hibernate.jdbc.fetch_size">50</prop>
            <prop key="hibernate.jdbc.batch_size">10</prop>
            <prop key="hibernate.show_sql">true</prop>
        </props>
        </property>
    </bean>
</beans>

错误堆栈：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'wikiService' defined in file [/home/user/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/MyApp/WEB-INF/classes/com/wiki/service/WikiServiceImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.wiki.service.WikiServiceImpl]: No default constructor found; nested exception is java.lang.NoSuchMethodException: com.wiki.service.WikiServiceImpl.<init>()
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:997)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:943)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:385)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:284)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
    at java.util.concurrent.FutureTask.run(FutureTask.java:166)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.wiki.service.WikiServiceImpl]: No default constructor found; nested exception is java.lang.NoSuchMethodException: com.wiki.service.WikiServiceImpl.<init>()
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:72)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:990)
    ... 23 more

Stack表示容器找不到实际存在的默认构造函数。 应用程序正在TomCat 7.0 Server上运行。

感谢您的帮助。

Answer 1

由于您与我们共享的源代码无法出错，我的猜测是您的服务器包含旧类（即我们看到的源代码未被使用）。

我建议在IDE中清理项目以及Tomcat安装。

在Eclipse中的项目（如果那是你的IDE）：

Menu Project => Clean ...

在Eclipse中的Tomcat（如果那是你的IDE）：

Right click on the server in Servers view => Clean ...

Answer 2

您确定您已经为上面的代码中的WikiServiceImpl定义了默认构造函数吗？ 可能这个article可能会有所帮助。