Hibernate 5.x + Spring 5.x，无法在 DAOImpl class 中自动装配 SessionFactory
Hibernate 5.x + Spring 5.x, can't autowire SessionFactory in DAOImpl class
我正在编写一个非常简单的 crm Web 应用程序，但在我的一个 DAO classes 中自动装配休眠 sessionFactory bean 时遇到问题。我已经在互联网上搜索了几天，我很困惑，因为我的配置似乎反映了那些据说在网上工作的配置。在这个项目中我不使用 xml's.
web servlet 配置class
public class WebServletConfig implements WebApplicationInitializer
{
@Override
public void onStartup(ServletContext servletContext) throws ServletException
{
AnnotationConfigWebApplicationContext webContext = new AnnotationConfigWebApplicationContext();
webContext.register(SpringConfig.class);
webContext.setServletContext(servletContext);
ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(webContext));
servlet.setLoadOnStartup(1);
servlet.addMapping("/");
}
}
spring 配置 class
@Configuration
@EnableWebMvc
@ComponentScan("com.crmproject")
public class SpringConfig implements WebMvcConfigurer
{
@Bean
public ViewResolver viewResolver()
{
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/pages/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
@Bean
public MessageSource messageSource()
{
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
messageSource.setBasename("resources/messages");
return messageSource;
}
public void configureDefaultSevletHandling(DefaultServletHandlerConfigurer configurer)
{
configurer.enable();
}
}
休眠配置文件
@Configuration
public class HibernateConfig
{
@Bean
public LocalSessionFactoryBean sessionFactory()
{
LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
sessionFactory.setDataSource(dataSource());
sessionFactory.setPackagesToScan("com.crmproject.entity");
sessionFactory.setHibernateProperties(hibernateProperties());
return sessionFactory;
}
@Bean
public DataSource dataSource()
{
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
dataSource.setUrl("jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false&serverTimezone=UTC");
dataSource.setUsername("hbstudent");
dataSource.setPassword("hbstudent");
return dataSource;
}
private final Properties hibernateProperties()
{
Properties hibernateProperties = new Properties();
hibernateProperties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
hibernateProperties.setProperty("hibernate.show_sql", "true");
return hibernateProperties;
}
}
我正在尝试在此 DAO class 中自动装配 sessionFactory，但是当我调用 testMethod 查看是否已注入 sessionFactory 时，它抛出 NullPointerException.
@Repository
public class CustomerDAOImpl implements CustomerDAO
{
@Autowired
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sessionFactory)
{
this.sessionFactory = sessionFactory;
}
public void testMethod()
{
System.out.println(sessionFactory.toString());
}
public CustomerDAOImpl()
{
System.out.println("in CustomerDAOImpl constructor");
}
public List<Customer> getCustomers()
{
return null;
}
public Integer saveCustomer(Customer customer)
{
return null;
}
public Customer getCustomer(Integer id)
{
return null;
}
public boolean updateCustomer(Integer id, Customer customer)
{
return false;
}
public boolean deleteCustomer(Integer id)
{
return false;
}
}
异常：
SEVERE: Servlet.service() for servlet [dispatcher] in context with
path [/crm2-project] threw exception [Request processing failed;
nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException at
com.crmproject.dao.CustomerDAOImpl.testMethod(CustomerDAOImpl.java:26)
at
com.crmproject.controller.CustomerController.listCustomers(CustomerController.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498) at
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
at
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
at
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
at
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
at
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
at
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
at
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
at
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
at
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) at
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:501)
at
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
at
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376)
at
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
为什么 Spring 不注入 sessionFactory bean？
编辑：
每个请求添加控制器代码
@Controller
@RequestMapping("/customer")
public class CustomerController
{
@RequestMapping("/customerAddForm")
public String showAddCustomerForm(Model model)
{
model.addAttribute("customer", new Customer());
System.out.println("Inside showAddCustomerForm method");
return "customer-add-form";
}
@RequestMapping("/list")
public String listCustomers(Model model)
{
List<Customer> customers = new ArrayList<>();
new CustomerDAOImpl().testMethod();
model.addAllAttributes(customers);
return "list-customers";
}
@RequestMapping("/proccessAddForm")
public void proccessAddForm(@ModelAttribute("customer")Customer customer)
{
System.out.println("Inside proccessAddForm method, customer: " + customer.toString());
}
}
问题出在我的控制器 class 上。我尝试使用 "new CustomerDAOImpl().testMethod();" 创建 CustomerDAOImpl 对象。 Spring 显然不喜欢。我把它改成了
“@Autowired
CustomerDAOImpl customerDAOImpl;”，现在可以正常工作了，NullPointerException 消失了。多么愚蠢的错误，但同时也是一次很棒的学习经历。感谢您的帮助！
我正在编写一个非常简单的 crm Web 应用程序，但在我的一个 DAO classes 中自动装配休眠 sessionFactory bean 时遇到问题。我已经在互联网上搜索了几天，我很困惑，因为我的配置似乎反映了那些据说在网上工作的配置。在这个项目中我不使用 xml's.
web servlet 配置class
public class WebServletConfig implements WebApplicationInitializer
{
@Override
public void onStartup(ServletContext servletContext) throws ServletException
{
AnnotationConfigWebApplicationContext webContext = new AnnotationConfigWebApplicationContext();
webContext.register(SpringConfig.class);
webContext.setServletContext(servletContext);
ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(webContext));
servlet.setLoadOnStartup(1);
servlet.addMapping("/");
}
}
spring 配置 class
@Configuration
@EnableWebMvc
@ComponentScan("com.crmproject")
public class SpringConfig implements WebMvcConfigurer
{
@Bean
public ViewResolver viewResolver()
{
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/pages/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
@Bean
public MessageSource messageSource()
{
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
messageSource.setBasename("resources/messages");
return messageSource;
}
public void configureDefaultSevletHandling(DefaultServletHandlerConfigurer configurer)
{
configurer.enable();
}
}
休眠配置文件
@Configuration
public class HibernateConfig
{
@Bean
public LocalSessionFactoryBean sessionFactory()
{
LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
sessionFactory.setDataSource(dataSource());
sessionFactory.setPackagesToScan("com.crmproject.entity");
sessionFactory.setHibernateProperties(hibernateProperties());
return sessionFactory;
}
@Bean
public DataSource dataSource()
{
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
dataSource.setUrl("jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false&serverTimezone=UTC");
dataSource.setUsername("hbstudent");
dataSource.setPassword("hbstudent");
return dataSource;
}
private final Properties hibernateProperties()
{
Properties hibernateProperties = new Properties();
hibernateProperties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
hibernateProperties.setProperty("hibernate.show_sql", "true");
return hibernateProperties;
}
}
我正在尝试在此 DAO class 中自动装配 sessionFactory，但是当我调用 testMethod 查看是否已注入 sessionFactory 时，它抛出 NullPointerException.
@Repository
public class CustomerDAOImpl implements CustomerDAO
{
@Autowired
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sessionFactory)
{
this.sessionFactory = sessionFactory;
}
public void testMethod()
{
System.out.println(sessionFactory.toString());
}
public CustomerDAOImpl()
{
System.out.println("in CustomerDAOImpl constructor");
}
public List<Customer> getCustomers()
{
return null;
}
public Integer saveCustomer(Customer customer)
{
return null;
}
public Customer getCustomer(Integer id)
{
return null;
}
public boolean updateCustomer(Integer id, Customer customer)
{
return false;
}
public boolean deleteCustomer(Integer id)
{
return false;
}
}
异常：
SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/crm2-project] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause java.lang.NullPointerException at com.crmproject.dao.CustomerDAOImpl.testMethod(CustomerDAOImpl.java:26) at com.crmproject.controller.CustomerController.listCustomers(CustomerController.java:31) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:501) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)
为什么 Spring 不注入 sessionFactory bean？
编辑： 每个请求添加控制器代码
@Controller
@RequestMapping("/customer")
public class CustomerController
{
@RequestMapping("/customerAddForm")
public String showAddCustomerForm(Model model)
{
model.addAttribute("customer", new Customer());
System.out.println("Inside showAddCustomerForm method");
return "customer-add-form";
}
@RequestMapping("/list")
public String listCustomers(Model model)
{
List<Customer> customers = new ArrayList<>();
new CustomerDAOImpl().testMethod();
model.addAllAttributes(customers);
return "list-customers";
}
@RequestMapping("/proccessAddForm")
public void proccessAddForm(@ModelAttribute("customer")Customer customer)
{
System.out.println("Inside proccessAddForm method, customer: " + customer.toString());
}
}
问题出在我的控制器 class 上。我尝试使用 "new CustomerDAOImpl().testMethod();" 创建 CustomerDAOImpl 对象。 Spring 显然不喜欢。我把它改成了 “@Autowired CustomerDAOImpl customerDAOImpl;”，现在可以正常工作了，NullPointerException 消失了。多么愚蠢的错误，但同时也是一次很棒的学习经历。感谢您的帮助！