java - 通用 DAO 实现， Controller 级别注入(inject)失败

Question

  import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import java.util.Map;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import javax.persistence.Transient;

import org.apache.log4j.Logger;
import org.springframework.dao.DataAccessException;


/**
 * Generic DAO implementation class that provides basic Data access and
 * manipulation functionality
 * 
 * @author syed.ammar
 * 
 */
public abstract class GenericDAOImpl<T> implements GenericDAO<T> {

    private static Logger logger = Logger.getLogger(GenericDAOImpl.class);

    @SuppressWarnings("unchecked")
    protected Class<T> clazz = (Class<T>) ((ParameterizedType) this.getClass().getGenericSuperclass()).getActualTypeArguments()[0];

    @PersistenceContext
    protected EntityManager entityManager;

    public EntityManager getEntityManager() {
        return entityManager;
    }

    public void setEntityManager(EntityManager entityManager) {
        this.entityManager = entityManager;
    }

    @Override
    public T save(T entity) throws DataAccessException {
        logger.debug("Merging Object of Type: " + entity.getClass().getCanonicalName());
        entity = entityManager.merge(entity);
        return entity;
    }

    @Override
    public void persist(T entity) throws DataAccessException {
        logger.debug("Persisting Object of Type: " + entity.getClass().getCanonicalName());
        entityManager.persist(entity);
    }


    /**
     * This method update record in database
     * 
     * @param updatableObj
     *            - the updated copy to merge
     * @return the updated, registered persistent instance
     * */
    @Override
    public T update(T entity) {
        return save(entity);
    }

    /**
     * Delete the given entity.
     * 
     * @param entityClass
     *            - the entityClass to delete
     * */
    @Override
    public void delete(T entity) {
        logger.debug("Delete entity of Type: " + entity.getClass().getCanonicalName());
        entityManager.remove(entity);
    }

    /**
     * Delete all given entities.
     * 
     * @param entities
     *            - the entities to delete
     * */
    public void deleteAll(List<T> entities) {
        for (T entity : entities) {
            delete(entity);
        }
    }

    /**
     * Delete Entity by Id
     * @param id
     *      - Entity Id 
     */
    @Override
    public int deleteById(Long id) {
        Query deleteQuery = entityManager.createQuery("DELETE FROM " + clazz.getName() + " entity WHERE entity.id=:id");
        deleteQuery.setParameter("id", id);
        return deleteQuery.executeUpdate();     
    }

    /**
     * Delete Entity by Customer
     * @param customer
     *      - Customer Entity 
     */
/*  @Override
    public int deleteByCustomer(Customer customer) {
        Query deleteQuery = entityManager.createQuery("DELETE FROM " + clazz.getName() + " entity WHERE entity.customer=:customer");
        deleteQuery.setParameter("customer", customer);
        return deleteQuery.executeUpdate();
    }
*/  
    /**
     * Delete Entity by Reseller
     * @param reseller
     *      - Reseller Entity 
     */
/*  @Override
    public int deleteByReseller(Reseller reseller) {
        Query deleteQuery = entityManager.createQuery("DELETE FROM " + clazz.getName() + " entity WHERE entity.customer.reseller=:reseller");
        deleteQuery.setParameter("reseller", reseller);
        return deleteQuery.executeUpdate();
    }
*/
    /**
     * Read the entity instance of the given class with the given id, throwing
     * an exception if not found. Retrieves read-write objects from the
     * hibernate UnitOfWork in case of a non-read-only transaction, and
     * read-only objects else.
     * @param id
     *            - Identity key of the desired object
     * @return the entity instance
     * */
    @Override
    public T getById(Long id) {
        logger.debug("getById:" + id + ", T class: " + clazz );
        return entityManager.find(clazz, id);
    }

    @Override
    public List<T> getResultList(String jpql, Map<String, Object> queryParams) {
        logger.debug("Query: " + jpql);
        Query query = entityManager.createQuery(jpql.toString());
        for(Map.Entry<String, Object> entry : queryParams.entrySet()){
            query.setParameter(entry.getKey(), entry.getValue());
        }
        @SuppressWarnings("unchecked")
        List<T> resultList = (List<T>) query.getResultList();
        return resultList;
    }

    /**
     * Generic search method without sort column and direction which searches
     * the record depending upon property values set in the passed model bean. 
     * This method has been deprecated and will be removed soon. Create Query 
     * specific methods in related Entity DAO's instead.
     * 
     * @param entity
     *            Entity with data set for criteria search
     * @return List of searched model beans by applying the passed values of
     *         model bean as criteria
     */
    @Override
    @Deprecated
    public List<T> search(T entity) {
        return search(entity, null, null);
    }

    /**
     * Generic search method which searches the record depending upon property
     * values set in the passed model bean. 
     * This method has been deprecated and will be removed soon. Create Query 
     * specific methods in related Entity DAO's instead.
     * 
     * @param entity
     *            Entity with data set for criteria search
     * @param sortByColumn
     *            Name of column to be used for sorting result
     * @param sortDirection
     *            1: ASC 2:DESC
     * @return List of searched model beans by applying the passed values of
     *         model bean as criteria
     */
    @Override
    @Deprecated
    @SuppressWarnings("unchecked")
    public List<T> search(T entity, String sortByColumn, Long sortDirection) {
        List<Object> params = new ArrayList<Object>();
        String query = "SELECT entity FROM " + clazz.getName() + " entity";

        Field[] publicFields = entity.getClass().getDeclaredFields();
        for (Field field : publicFields) {
            field.setAccessible(true);
            Object value = null;
            try {
                value = field.get(entity);
            } catch (IllegalArgumentException e) {
                logger.error("", e);
            } catch (IllegalAccessException e) {
                logger.error("", e);
            }
            if (value == null
                    || Collection.class.isAssignableFrom(field.getType())
                    || java.lang.reflect.Modifier.isStatic(field.getModifiers())
                    || field.getAnnotation(Transient.class) != null) {
                continue;
            }
            if (field.getType().equals(String.class)) {
                if (query.contains("where")) {
                    query = query + " and " + field.getName() + " like ?"
                            + params.size();
                } else {
                    query = query + " where " + field.getName() + " like ?"
                            + params.size();
                }
                params.add("%" + value.toString() + "%");
            } else if (field.getType().equals(Date.class)) {
                Date startDateTime = null;
                Date endDateTime = null;
                String startTime = DATE_FORMAT.format(value) + " 00:00:00";
                String endTime = DATE_FORMAT.format(value) + " 23:59:59";
                try {
                    startDateTime = DATE_TIME_FORMAT.parse(startTime);
                    endDateTime = DATE_TIME_FORMAT.parse(endTime);
                } catch (ParseException e) {
                    logger.error("", e);
                }
                if (startDateTime == null || endDateTime == null) {
                    continue;
                }
                if (query.contains("where")) {
                    query = query + " and " + field.getName() + " between ?"
                            + params.size() + " and ?" + (params.size() + 1);
                } else {
                    query = query + " where " + field.getName() + " between ?"
                            + params.size() + " and ?" + (params.size() + 1);
                }

                params.add(startDateTime);
                params.add(endDateTime);
            } else {
                if (query.contains("where")) {
                    query = query + " and " + field.getName() + " = "
                            + params.size();
                } else {
                    query = query + " where " + field.getName() + " = ?"
                            + params.size();
                }
                params.add(value);
            }
        }

        Query queryObj = entityManager.createQuery(query);

        // Check is sorting parameters are not not blank or null, apply sorting
        // criteria
        if (sortByColumn != null && sortDirection != null) {
            if (sortDirection == 1L) {
                query = query + " Order By " + sortByColumn + " ASC";
            } else {
                query = query + " Order By " + sortByColumn + " DESC";
            }
            if (params.size() > 0) {
                for (int i = 0; i < params.size(); i++) {
                    queryObj.setParameter(i, params.get(i));
                }
            }
        }

        return queryObj.getResultList();
    }

    @Override
    public List<T> getAll() {
        return getAll(null, null);
    }

    @Override
    public List<T> getAll(String sortByColumn, Long sortDirection) {
        String query = "SELECT entity FROM " + clazz.getName() + " entity";
        if (sortByColumn != null && sortDirection != null) {
            if (sortDirection == 1L) {
                query = query + " Order By " + sortByColumn + " ASC";
            } else {
                query = query + " Order By " + sortByColumn + " DESC";
            }
        }
        @SuppressWarnings("unchecked")
        List<T> resultList = (List<T>) entityManager.createQuery(query).getResultList();
        return resultList;
    }
    /**
     * Generic find method which identify the exact records depending upon
     * property values set in the passed model bean else null will be returned
     * 
     * @param entity
     *            Entity with data set for criteria search
     * @return List of identified model beans by applying the passed values of
     *         model bean as criteria
     */
    @Override
    @SuppressWarnings("unchecked")
    public List<T> find(T entity) {
        List<Object> params = new ArrayList<Object>();
        String query = "SELECT entity FROM " + entity.getClass().getName()
                + " entity";

        Field[] publicFields = entity.getClass().getDeclaredFields();
        for (Field field : publicFields) {
            field.setAccessible(true);
            Object value = null;

            try {
                value = field.get(entity);
            } catch (IllegalArgumentException e) {
                logger.error("", e);
            } catch (IllegalAccessException e) {
                logger.error("", e);
            }
            if (value == null
                    || Collection.class.isAssignableFrom(field.getType())
                    || java.lang.reflect.Modifier.isStatic(field.getModifiers())
                    || field.getAnnotation(Transient.class) != null) {
                continue;
            }

            if (field.getType().equals(Date.class)) {
                Date startDateTime = null;
                Date endDateTime = null;
                String startTime = DATE_FORMAT.format(value) + " 00:00:00";
                String endTime = DATE_FORMAT.format(value) + " 23:59:59";               
                try {
                    startDateTime = DATE_TIME_FORMAT.parse(startTime);
                    endDateTime = DATE_TIME_FORMAT.parse(endTime);
                } catch (ParseException e) {
                    logger.error("", e);
                }
                if (startDateTime == null || endDateTime == null) {
                    continue;
                }
                if (query.contains("where")) {
                    query = query + " and " + field.getName() + " between ?"
                            + params.size() + " and ?" + (params.size() + 1);
                } else {
                    query = query + " where " + field.getName() + " between ?"
                            + params.size() + " and ?" + (params.size() + 1);
                }
                params.add(startDateTime);
                params.add(endDateTime);
            } else {
                if (query.contains("where")) {
                    query = query + " and " + field.getName() + " = ?"
                            + params.size();
                } else {
                    query = query + " where " + field.getName() + " = ?"
                            + params.size();
                }
                params.add(value);
            }
        }
        if (params.size() > 0) {
            Query queryObj = entityManager.createQuery(query);

            for (int i = 0; i < params.size(); i++) {
                queryObj.setParameter(i, params.get(i));
            }
            return queryObj.getResultList();
        } else {
            return null;
        }
    }
}

///自动连线

@Controller
public class CourseController   {

//  @Autowired
//  private SearchService searchService;

    @Autowired
    CourseDAOImp courseDAO;
    //..............
}

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'courseController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.softech.ls360.lcms.contentbuilder.dao.impl.CourseDAOImp com.softech.ls360.lcms.contentbuilder.web.controller.CourseController.courseDAO; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.softech.ls360.lcms.contentbuilder.dao.impl.CourseDAOImp] 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)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:285) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1074) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:618) at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:963) at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1600) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:744) Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.softech.ls360.lcms.contentbuilder.dao.impl.CourseDAOImp com.softech.ls360.lcms.contentbuilder.web.controller.CourseController.courseDAO; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.softech.ls360.lcms.contentbuilder.dao.impl.CourseDAOImp] 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)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:502) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:84) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:282) ... 26 more Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.softech.ls360.lcms.contentbuilder.dao.impl.CourseDAOImp] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:920) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:789) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:703) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:474) ... 28 more

Answer 1

您应该在 xml 中定义 bean

或者给entry of <context:component-scan base-package=" " />