java - GenericDAO + Spring + JPA2 没有独特的 bean

Question

在这里查看了几个类似的问题并将逻辑应用于我的情况后，我仍然对我的 Spring/JPA 应用程序中的依赖项注入(inject)失败感到困惑。申请的前提是:

• 使用基于 JPA2 的注释来减少 xml 配置；
• 根据引用教程使用@Autowire 为每个 DAO 类型从单个接口(interface)/实现自动生成 DAO here ;

这是 fatal error :

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'exampleInstanceBO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.***.dao.IGenericDAO com.***.bo.ExampleInstanceBO.dao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.***.dao.IGenericDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=IGenericDAO)}

...这是由链条进一步向下引起的:​​

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.***.dao.IGenericDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency.

它在以下服务类中被调用:

示例实例BO:

    import org.springframework.beans.factory.annotation.Autowired;    import org.springframework.beans.factory.annotation.Qualifier;    import org.springframework.stereotype.Service;    import com.***.dao.*;    import com.***.entity.*;    @Service    public class ExampleInstanceBO {        @Autowired        @Qualifier(value="IGenericDAO")        IGenericDAO dao;        public void setDao( final IGenericDAO daoToSet ){            dao = daoToSet;            dao.setClazz( ExampleInstance.class );        }            //    } 

IGenericDAO is as follows:

IGenericDAO:

    import org.springframework.stereotype.Component;    import org.springframework.stereotype.Service;    @Component("IGenericDAO")    public interface IGenericDAO {        public void setClazz(final Class clazzToSet);        public T findById( final Long id );        public List findAll();        public void save( final T entity );        public void update( final T entity );        public void delete( final T entity );        public void deleteById( final Long entityId );    }

Its implementation is as follows:

GenericDAO

    import java.io.Serializable;      import org.springframework.context.annotation.Scope;    import org.springframework.stereotype.Repository;    @Repository    @Scope("prototype")    public class GenericDAO extends AbstractDAO implements IGenericDAO{       //empty, because most functionality in abstract class AbstractDAO    }

AbstractDAO

    import java.io.Serializable;    import java.util.List;        import javax.persistence.EntityManager;    import javax.persistence.PersistenceContext;    import org.springframework.stereotype.Service;    /**     * @author ----     *     */    @Service    public abstract class AbstractDAO {           private Class clazz;           @PersistenceContext           EntityManager entityManager;           public void setClazz( final Class clazzToSet ){              this.clazz = clazzToSet;           }           public T findById( final Long id ){              return entityManager.find( clazz, id );           }           public List findAll(){              return entityManager.createQuery( "from " + clazz.getName() )               .getResultList();           }    // other save/delete/update etc. methods here    }

The above is based on the discussion here which takes quite a lot for granted in terms of config and dependencies. Here are my config and pom files which quite possibly are contributing to the confusion, as they've evolved while I've been trying to sort this out.

beanDefinitions.xml

<jpa:repositories base-package="com.***" />
<context:component-scan base-package="com.***" />

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

<bean id="entityManagerFactory"
  class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
  <property name="dataSource" ref="dataSource" />
  <property name="packagesToScan" value="***" />
  <property name="jpaVendorAdapter">
    <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
      <property name="generateDdl" value="true" />
      <property name="database" value="HSQL" />
    </bean>
  </property>
</bean>

<bean 
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location">
        <value>database.properties</value>
    </property>
</bean>

<bean id="dataSource" 
         class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${jdbc.driverClassName}" />
    <property name="url" value="${jdbc.url}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
</bean>
</beans>

最后，pom.xml:

    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>maven_projects</groupId>
    <artifactId>***</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>***</name>
    <description>spring 3 plus maven</description>
    <packaging>war</packaging>
    <properties>
        <org.springframework.version>3.1.3.RELEASE</org.springframework.version>
        <hibernate.version>4.1.0.Final</hibernate.version>
        <mysql.version>5.1.13</mysql.version>
        <junit.version>4.7</junit.version>
        <slf4j.version>1.7.0</slf4j.version>
    </properties>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${org.springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${org.springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-core</artifactId>
            <version>${org.springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-web</artifactId>
            <version>${org.springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-config</artifactId>
            <version>${org.springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <!-- logging -->
        <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>jcl-over-slf4j</artifactId>
          <version>${slf4j.version}</version>
       </dependency>
       <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-api</artifactId>
          <version>${slf4j.version}</version>
       </dependency>
       <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-log4j12</artifactId>
          <version>${slf4j.version}</version>
       </dependency>
       <dependency>
          <groupId>log4j</groupId>
          <artifactId>log4j</artifactId>
          <version>1.2.14</version>
       </dependency>
        <!-- ORM/DB -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${org.springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
            <!-- perhaps using scope = provided, as this will often
             be present on the app server -->
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <!-- or hibernate-entitymanager if you use jpa -->
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
                <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.2.0.RELEASE</version>
        </dependency>
        <!-- 
            default Jave EE jars don't include code necessary for
         bytecode enhancement so we use these instead --> 
        <dependency>
            <groupId>org.jboss.spec</groupId>
            <artifactId>jboss-javaee-6.0</artifactId>
            <version>1.0.0.Final</version>
            <type>pom</type>
            <scope>provided</scope>
        </dependency>

        <!-- Jersey (RESTful web services -->
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-server</artifactId>
            <version>1.8</version>
        </dependency>
        <!-- Jersey + Spring -->
        <dependency>
            <groupId>com.sun.jersey.contribs</groupId>
            <artifactId>jersey-spring</artifactId>
            <version>1.8</version>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-core</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-web</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-beans</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-context</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-aop</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>2.2</version>
        </dependency>
    </dependencies>

    <!-- 
        Required for J2EE dependencies, see here: 
        http://www.ninthavenue.com.au/java-lang-classformaterror-exception-with-eclipselink-static-weaving-solved   
     -->
    <repositories>
        <repository>
        <id>repository.jboss.org-public</id>
        <name>JBoss repository</name>
        <url>https://repository.jboss.org/nexus/content/groups/public</url>
        </repository>
    </repositories>


</project>

** 更新**

谢谢，试过了，GenericDAO 现在看起来像这样:

    // @Component("GenericDAO")     @Repository("GenericDAO")     @Scope("prototype")     public class GenericDAO extends AbstractDAO implements IGenericDAO{     //     }

Using either the Component or the Repository annotation, still the same result. Looking at the log output, the beans that are generated are as follows:

... GenericDAO ... But it's looking for IGenericDAO - when I change to @Repository("IGenericDAO") it throws a null pointer exception, - baffled!

UPDATE #2 - datasource config:

<?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:jpa="http://www.springframework.org/schema/data/jpa"
   xmlns:context="http://www.springframework.org/schema/context"
   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-2.5.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">

<!--<jpa:repositories base-package="***" />-->
<context:component-scan base-package="***" />

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

<bean id="entityManagerFactory"
  class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
  <property name="dataSource" ref="dataSource" />
  <property name="packagesToScan" value="***" />
  <property name="jpaVendorAdapter">
    <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
      <property name="generateDdl" value="true" />
      <property name="database" value="HSQL" />
    </bean>
  </property>
</bean>

<bean 
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location">
        <value>database.properties</value>
    </property>
</bean>

<bean id="dataSource" 
         class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${jdbc.driverClassName}" />
    <property name="url" value="${jdbc.url}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
</bean>
</beans>

Answer 1

将 @Component 注释放在您的 GenericDAO 上，而不是接口(interface)上。