如何解决BeanCreationException？

Question

使用Spring 4 CRUD应用程序，该应用程序完全基于注释，并且不使用XML配置。

以下是异常的堆栈延迟：

ImageIcon img1 = new ImageIcon("aib.jpg");

以下是Java文件

HibernateConfiguration.java

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'employeeController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.springrest.annotationbased.crudexampleapplication.service.EmployeeService com.springrest.annotationbased.crudexampleapplication.controller.EmployeeController.employeeService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'employeeService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.springrest.annotationbased.crudexampleapplication.dao.EmployeeDao com.springrest.annotationbased.crudexampleapplication.service.EmployeeServiceImpl.employeeDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'employeeDao': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.hibernate.SessionFactory com.springrest.annotationbased.crudexampleapplication.dao.EmployeeDaoImpl.sessionFactory; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class com.springrest.annotationbased.crudexampleapplication.configuration.HibernateConfiguration: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public org.springframework.orm.hibernate4.LocalSessionFactoryBean com.springrest.annotationbased.crudexampleapplication.configuration.HibernateConfiguration.sessionFactory()] threw exception; nested exception is java.lang.NullPointerException
            at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
            at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
            at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
            at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
            at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
            at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
            at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
            at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
            at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:703)
            at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
            at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
            at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
            at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
            at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
            at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4851)
            at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5314)
            at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
            at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
            at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
            at java.util.concurrent.FutureTask.run(FutureTask.java:266)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
            at java.lang.Thread.run(Thread.java:745)

package com.springrest.annotationbased.crudexampleapplication.configuration; @Configuration @EnableTransactionManagement @ComponentScan({ "com.springrest.annotationbased.crudexampleapplication" }) @PropertySource(value = "classpath:application.properties") public class HibernateConfiguration { @Autowired private Environment env; @Bean public LocalSessionFactoryBean sessionFactory() { LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean(); Properties props = new Properties(); // Setting JDBC properties props.put("mysql.driver", env.getProperty("mysql.driver")); props.put("mysql.url", env.getProperty("mysql.url")); props.put("mysql.user", env.getProperty("mysql.user")); props.put("mysql.password", env.getProperty("mysql.password")); // Setting Hibernate properties props.put("hibernate.show_sql", env.getProperty("hibernate.show_sql")); props.put("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto")); props.put("hibernate.dialect", env.getProperty("org.hibernate.dialect.MySQLDialect")); sessionFactory.setPackagesToScan(new String[] { "com.springrest.annotationbased.crudexampleapplication.model" }); sessionFactory.setHibernateProperties(props); return sessionFactory; } @Bean @Autowired public HibernateTransactionManager transactionManager(SessionFactory s) { HibernateTransactionManager txManager = new HibernateTransactionManager(); txManager.setSessionFactory(s); return txManager; }}

MyWebAppInitializer.java

package com.springrest.annotationbased.crudexampleapplication.configuration; public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { @Override protected Class<?>[] getRootConfigClasses() { // TODO Auto-generated method stub return new Class[] { HibernateConfiguration.class }; } @Override protected Class<?>[] getServletConfigClasses() { // TODO Auto-generated method stub return new Class[] { WebConfig.class }; } @Override protected String[] getServletMappings() { // TODO Auto-generated method stub return new String[] { "/" }; } }

WebConfig.java

package com.springrest.annotationbased.crudexampleapplication.configuration; @Configuration @EnableWebMvc @ComponentScan(basePackages="com.springrest.annotationbased.crudexampleapplication") public class WebConfig extends WebMvcConfigurerAdapter { }

EmployeeController.java

@RestController public class EmployeeController { @Autowired EmployeeService employeeService; //logic goes here }

EmployeeServiceImpl

@Service("employeeService") @Transactional public class EmployeeServiceImpl implements EmployeeService { @Autowired private EmployeeDao employeeDao; // business logic }

EmployeeDaoImpl.java

@Repository("employeeDao") public class EmployeeDaoImpl implements EmployeeDao { @Autowired private SessionFactory sessionFactory; // persistence logic }

EmployeeEntity.java

Application.properties

 @Entity
 @Table(name="employee")
 public class EmployeeEntity implements Serializable{

 private static final long serialVersionUID = 1L;

 @Id
 @GeneratedValue(strategy = GenerationType.AUTO)
 @Column(name="empid")
 private Integer employeeId;

 @Column(name="empname")
 private String employeeName;

 @Column(name="empAddress")
 private String employeeAddress;

@Column(name="salary")
private Long salary;

@Column(name="empAge")
private Integer employeeAge;

        // getters and setters

}

Answer 1

在HibernateConfiguration.java中，您已经给自己的变量集作为put方法中的键。这是错误的，您必须将其称为

// Setting JDBC properties
        props.put(DRIVER, env.getProperty("mysql.driver"));
        props.put(URL, env.getProperty("mysql.jdbcUrl"));
        props.put(USER, env.getProperty("mysql.username"));
        props.put(PASS, env.getProperty("mysql.password"));

    // Setting Hibernate properties
    props.put(SHOW_SQL, env.getProperty("hibernate.show_sql"));
    props.put(HBM2DDL_AUTO, env.getProperty("hibernate.hbm2ddl.auto"));
    props.put(DIALECT, env.getProperty("hibernate.dialect"));

在这里，     DRIVER，URL，USER等是静态变量，并确保已导入以下包，

import static org.hibernate.cfg.Environment.*;