BeanCreationException：无法自动装配字段和java.lang.NullPointerException

Question

我一直在研究Hibernate 4和Spring 4.我收到了这个错误并且在过去的4天里一直在努力。 我已经在互联网上尝试了所有这些问题的所有解决方案，但它们都没有奏效。请帮帮我。

Here is my project structure.

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0': Invocation of init method failed; nested exception is org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.cumulis.dao.impl.TrackDAOImpl] for bean with name 'trackDAO' defined in ServletContext resource [/WEB-INF/spring/appServlet/servlet-context.xml]; nested exception is java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
Related cause: org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.cumulis.dao.impl.TrackDAOImpl] for bean with name 'trackDAO' defined in ServletContext resource [/WEB-INF/spring/appServlet/servlet-context.xml]; nested exception is java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)


Caused by: org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.cumulis.dao.impl.TrackDAOImpl] for bean with name 'trackDAO' defined in ServletContext resource [/WEB-INF/spring/appServlet/servlet-context.xml]; nested exception is java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1351)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:628)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:597)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1444)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:445)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:423)

Caused by: java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1333)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1167)


Related cause:
org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.cumulis.dao.impl.TrackDAOImpl] for bean with name 'trackDAO' defined in ServletContext resource [/WEB-INF/spring/appServlet/servlet-context.xml]; nested exception is java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1351)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:628)

Caused by: java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1333)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1167)
java.lang.ClassNotFoundException: com.cumulis.dao.impl.TrackDAOImpl
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1333)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1167)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:250)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:250)


java.lang.NullPointerException
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1526)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1505)
    at org.hibernate.cfg.Configuration.configure(Configuration.java:1440)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:348)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)

的pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>net.codejava</groupId>
    <artifactId>cumulis</artifactId>
    <name>CRUDWebApp</name>
    <packaging>war</packaging>
    <version>1.0.0-BUILD-SNAPSHOT</version>
  <properties>
    <java-version>1.8.0.6</java-version>
    <org.springframework.version>4.2.2.RELEASE</org.springframework.version>
    <org.aspectj-version>1.6.10</org.aspectj-version>
  </properties>

   <repositories>
        <repository>
        <id>Java.Net</id>
        <url>http://download.java.net/maven/2/</url>
    </repository>
  </repositories>

  <dependencies>
        <!-- To correct java.lang.ClassNotFoundException: com.sun.faces.config.ConfigureListener error on Tomcat startup -->   
      <dependency>
        <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.2.12</version>
            </dependency>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.2.12</version>
        </dependency>


    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</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</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <!-- AspectJ -->
    <dependency>
        <groupId>org.aspectj</groupId>
        <artifactId>aspectjrt</artifactId>
        <version>${org.aspectj-version}</version>
    </dependency>   
    <!--  SLF4J seems to be required for Spring Framework -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.12</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.12</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>jcl-over-slf4j</artifactId>
        <version>1.7.12</version>
    </dependency>

    <!--        Hibernate ORM framework dependencies -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>4.3.5.Final</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>ejb3-persistence</artifactId>
        <version>3.3.2.Beta1</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-validator</artifactId>
        <version>5.2.2.Final</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-commons-annotations</artifactId>
        <version>3.3.0.ga</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-annotations</artifactId>
        <version>3.5.6-Final</version>
    </dependency>

    <dependency>
        <groupId>org.apache.taglibs</groupId>
        <artifactId>taglibs-standard-spec</artifactId>
        <version>1.2.5</version>
    </dependency>

    <dependency>
        <groupId>org.apache.taglibs</groupId>
        <artifactId>taglibs-standard-impl</artifactId>
        <version>1.2.5</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-core</artifactId>
        <version>4.0.2.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-taglibs</artifactId>
        <version>4.0.2.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.0-b01</version>
    </dependency>

    <dependency>
        <groupId>javax.transaction</groupId>
        <artifactId>jta</artifactId>
        <version>1.1</version>
    </dependency>

    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>7.0</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet.jsp.jstl</groupId>
        <artifactId>javax.servlet.jsp.jstl-api</artifactId>
        <version>1.2.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-dbcp2</artifactId>
        <version>2.1.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-pool2</artifactId>
        <version>2.4.2</version>
    </dependency>

    <dependency>
        <groupId>org.bgee.log4jdbc-log4j2</groupId>
        <artifactId>log4jdbc-log4j2-jdbc4</artifactId>
        <version>1.16</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.37</version>
    </dependency>

    <!--  Our Logging mechanism is based on log4j2 -->
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.4.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.4.1</version>
    </dependency>

    <!-- Test -->
    <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.7</version>
            <scope>test</scope>
    </dependency>        
    </dependencies>


    <build>
        <plugins>
            <plugin>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.9</version>
                <configuration>
                    <additionalProjectnatures>
                        <projectnature>org.springframework.ide.eclipse.core.springnature</projectnature>
                    </additionalProjectnatures>
                    <additionalBuildcommands>
                        <buildcommand>org.springframework.ide.eclipse.core.springbuilder</buildcommand>
                    </additionalBuildcommands>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.5.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <compilerArgument>-Xlint:all</compilerArgument>
                    <showWarnings>true</showWarnings>
                    <showDeprecation>true</showDeprecation>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <configuration>
                    <mainClass>org.test.int1.Main</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

这是我的TrackController.java。我知道@Component注释是多余的。

package com.cumulis.controller;

import java.util.List;
import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;   
import com.cumulis.dao.TrackDAO;
import com.cumulis.model.Track;
import com.cumulis.service.TrackService;

@Component
@Controller
public class TrackController {

    @Autowired
    private TrackDAO trackDao;

    @RequestMapping("/")
    public ModelAndView handleRequest() throws Exception {
        List<Track> trackList = trackDao.getAll();
        ModelAndView model = new ModelAndView("trackList");
        model.addObject("trackList", trackList);
        return model;
    }

    @RequestMapping(value = "/new", method = RequestMethod.GET)
    public ModelAndView newUser() {
        ModelAndView model = new ModelAndView("trackForm");
        model.addObject("track", new Track());
        return model;      
    }

    @RequestMapping(value = "/edit", method = RequestMethod.GET)
    public ModelAndView editUser(HttpServletRequest request) {
        int trackId = Integer.parseInt(request.getParameter("id"));
        Track track = trackDao.get(trackId);
        ModelAndView model = new ModelAndView("trackForm");
        model.addObject("track", track);
        return model;      
    }

    @RequestMapping(value = "/delete", method = RequestMethod.GET)
    public ModelAndView deleteUser(HttpServletRequest request) {
        int trackId = Integer.parseInt(request.getParameter("id"));
        trackDao.delete(trackId);
        return new ModelAndView("redirect:/");     
    }

    @RequestMapping(value = "/save", method = RequestMethod.POST)
    public ModelAndView saveTrack(@ModelAttribute Track track) {
        trackDao.update(track);
        return new ModelAndView("redirect:/");
    }  
}

TrackDAOImpl.java

package com.cumulis.dao.impl;
import java.util.List;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.servlet.ModelAndView;

import com.cumulis.dao.*;
import com.cumulis.model.*;

import org.hibernate.Criteria;
import org.hibernate.Query;

@Component
@Repository
public class TrackDAOImpl implements TrackDAO {


    private SessionFactory sessionFactory;

    public TrackDAOImpl() {
    }

    public TrackDAOImpl(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    @Override
    @Transactional
    public ModelAndView add(Track track) {
        sessionFactory.getCurrentSession().save(track);
        return null;
    }

    @Override
    @Transactional
    public Track get(long track_id){
         String hql = "from Track where id=" + track_id;
            Query query = sessionFactory.getCurrentSession().createQuery(hql);

            @SuppressWarnings("unchecked")
            List<Track> trackList = (List<Track>) query.list();

            if (trackList != null && !trackList.isEmpty()) {
                return trackList.get(0);
            }  
            return null;
        //return (Track)sessionFactory.getCurrentSession().get(Track.class, track_id);
    }

    @Override
    @Transactional
    public void delete(long track_id) {
        Track trackToDelete = new Track();
        trackToDelete.setId(track_id);
        sessionFactory.getCurrentSession().delete(trackToDelete);
        //sessionFactory.getCurrentSession().delete(track_id);

    }

    @Override
    @Transactional
    public void update(Track track) {
        sessionFactory.getCurrentSession().update(track);

    }

    @Override
    @Transactional
    public  List<Track>  getAll() {
         @SuppressWarnings("unchecked")
        List<Track> trackList = (List<Track>) sessionFactory.getCurrentSession()
                .createCriteria(Track.class)
                .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();

        return trackList;
    }

}

TrackDAO.java

package com.cumulis.dao;
import java.util.List;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.ModelAndView;
import com.cumulis.model.Track;

@Component
public interface TrackDAO {
    public ModelAndView add(Track track);
    public Track get(long track_id);
    public void delete(long track_id);
    public void update(Track track);
    public List<Track> getAll();
}

的hibernate.cfg.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping>
   <class name="com.cumulis.model.Track" table="track">
      <meta attribute="class-description">
         This class contains the track highlight and entry point
         to other data found in subtrack and trackpoint. 
      </meta>
      <id name="id" type="long" column="id">
         <generator class="native"/>
      </id>

      <property name="name" column="name" type="string"/>
      <property name="created" column="created" type="long"/>
      <property name="duration" column="duration" type="double"/>
      <property name="distance" column="distance" type="double"/>
      <property name="speed" column="speed" type="double"/>

   </class>
</hibernate-mapping>

servlet的context.xml中

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

            <!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->

            <!-- Enables the Spring MVC @Controller programming model -->
            <mvc:annotation-driven />

            <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
            <mvc:resources mapping="/resources/**" location="/resources/" />

            <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
            <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                <property name="prefix" value="/WEB-INF/views/" />
                <property name="suffix" value=".jsp" />
            </bean>

            <context:component-scan base-package="com.cumulis" />

            <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">
                <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/cumulis"/>
                <property name="username" value="root"/>
                <property name="password" value="xxxxxx"/>
            </bean> 

            <bean id="sessionFactory"
                class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
                <property name="dataSource" ref="dataSource" />
                <property name="packagesToScan">
                     <list>
                        <value>com.cumulis.controller</value>
                        <value>com.cumulis.dao</value>
                        <value>com.cumulis.dao.impl</value>
                        <value>com.cumulis.model</value>
                        <value>com.cumulis.service</value>
                        <value>com.cumulis.service.impl</value>
                     </list>
                </property>
                <property name="configLocation" value="/WEB-INF/hibernate.cfg.xml" />
                <property name="hibernateProperties">
                    <props>
                        <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                        <prop key="hibernate.show_sql">true</prop>
                    </props>
                </property>
            </bean>

            <tx:annotation-driven />
            <bean id="transactionManager"
                class="org.springframework.orm.hibernate4.HibernateTransactionManager">
                <property name="sessionFactory" ref="sessionFactory" />
            </bean>  

           <bean id="trackDAO" class="com.cumulis.dao.impl.TrackDAOImpl">
                <constructor-arg>
                    <ref bean="sessionFactory" />
                </constructor-arg>
            </bean>      

        </beans>

Answer 1

从以下类中删除@Component：

TrackDAO，TrackDAOImpl，TrackController

@Component是多余的，因为你已经在使用@ Repository，@ Controller等。

确保您还自动扫描班级所在的文件夹

XML和Java Config之间也有一个奇怪的组合。选择一个并坚持下去，没有必要同时运行。

编辑1： 如请求链接到示例，显示如何手动声明＆amp;自动扫描XML和Java Config。

http://www.mkyong.com/spring/spring-auto-scanning-components/

Answer 2

以下更改有效  @Controller         公共类TrackController {

        @Autowired
        private TrackDAO trackDao;

        @RequestMapping("/")
        public ModelAndView handleRequest() throws Exception {
            List<Track> trackList = trackDao.getAll();
            ModelAndView model = new ModelAndView("trackList");
            model.addObject("trackList", trackList);
            return model;
        }
...

和

    @Repository("TrackDAOImpl")
    public class TrackDAOImpl implements TrackDAO {

        @Autowired
        private SessionFactory sessionFactory;

        @Autowired
        public TrackDAOImpl(SessionFactory sessionFactory) {
            this.sessionFactory = sessionFactory;
        }

        @Override
        @Transactional
        public  List<Track>  getAll() {
             @SuppressWarnings("unchecked")
            List<Track> trackList = (List<Track>) sessionFactory.getCurrentSession()
                    .createCriteria(Track.class)
                    .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();

            return trackList;
        }
...

我还必须删除多个hibernate-annotation jar。我还必须在servlet-context.xml中更改它。

<bean id="TrackDAOImpl" class="com.cumulis.dao.TrackDAOImpl">
    <constructor-arg>
        <ref bean="sessionFactory" />
    </constructor-arg>
</bean>