使用@Repository、@Service 和@Controller 注释给出bean 创建异常？
Using @Repository, @Service and @Controller annotation giving bean creation exception?
我创建了一个简单的 spring mvc 项目来使用 STS 测试 spring 中的@Repository、@Service 和@Controller 注释。但是我收到了 BeanCreationException。
Spring 无法创建@Controller bean，因为它找不到带有@Service 注释的bean。
因为我使用过 STS，所以大部分文件都是自动创建的。我正在共享文件，请告诉我应该做哪些更改才能解决此问题。
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/root-context.xml</param-value>
</context-param>
<!-- Creates the Spring Container shared by all Servlets and Filters -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- Processes application requests -->
<servlet>
<servlet-name>appServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>appServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
servlet-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
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/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 -->
<annotation-driven />
<!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
<resources mapping="/resources/**" location="/resources/" />
<!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
<beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/" />
<beans:property name="suffix" value=".jsp" />
</beans:bean>
<context:component-scan base-package="com.example.annoproject.Controllers" />
<context:component-scan base-package="com.example.annoproject.Service" />
<context:component-scan base-package="com.example.annoproject.dao" />
</beans:beans>
root-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- Root Context: defines shared resources visible to all other web components -->
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/example_db" />
<property name="username" value="root" />
<property name="password" value="password" />
</bean>
<bean id = "jdbcTemplate" class = "org.springframework.jdbc.core.JdbcTemplate">
<constructor-arg ref = "dataSource"/>
</bean>
<bean id= "abstractService" class = "com.example.annoproject.service.AbstractService">
</bean>
</beans>
用户控制器
package com.example.annoproject.Controllers;
import com.example.annoproject.dao.UserDAOImpl;
import com.example.annoproject.model.User;
import com.example.annoproject.service.UserService;
@Controller
public class UserController {
@Autowired
UserService userService;
@RequestMapping(value = "/home", method = RequestMethod.GET)
public String signupPage(Model model){
userService.getUser("1");
return "home";
}
}
UserService.java
package com.example.annoproject.service;
import com.example.annoproject.dao.UserDAO;
import com.example.annoproject.model.User;
@Service("userService")
public class UserService {
@Autowired
UserDAO userDao;
public User getUser(String uid){
return userDao.getUser(uid);
}
}
UserDAOImpl.java
package com.example.annoproject.dao;
import com.example.annoproject.model.User;
@Repository("userDao")
public class UserDAOImpl implements UserDAO{
@Autowired
JdbcTemplate jdbcTemplate;
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
@Override
public User getUser(String id) {
String query = "SELECT * FROM empl where uid = ? ";
User user = jdbcTemplate.queryForObject(query, new Object[]{id}, new RowMapper<User>(){
@Override
public User mapRow(ResultSet rs, int rowNum) throws SQLException {
User user = new User();
user.setFirstName(rs.getString("empF"));
user.setLastName(rs.getString("emplL"));
return user;
}});
return user;
}
}
我尝试了很多东西。问题是在使用 @Controller UserController 时，尚未创建 userService bean。因此我们得到了例外。解决方案是在 root-context.xml 中定义 userService bean。但关键是我不想定义任何 bean，context <context:component-scan.. 应该已经解决了这个问题。由于 root-context 是第一个被读取的文件，如 web.xml - 部署描述符中所定义，我们需要更改那里的某些内容以便首先扫描包，并提前创建 userDao、userService、datasource 等 bean .但我无法巧妙地解决它。谁能告诉我标准做法是什么？我在这里错过了什么。谢谢。
顺便说一句，这里是 确切的例外：
WARN : org.springframework.web.context.support.XmlWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.example.annoproject.service.UserService com.example.annoproject.Controllers.UserController.userService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.example.annoproject.service.UserService] 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:298)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1148)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:293)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:191)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:636)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:934)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:602)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:521)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:462)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1241)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1154)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1041)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4944)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5230)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:714)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:581)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1683)
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)
您的上下文扫描包 com.example.annoproject.Service。但是你的服务在包裹com.example.annoproject.service.
遵守命名约定：包仅使用小写字母。你不会再犯这样的错误了。
我创建了一个简单的 spring mvc 项目来使用 STS 测试 spring 中的@Repository、@Service 和@Controller 注释。但是我收到了 BeanCreationException。 Spring 无法创建@Controller bean，因为它找不到带有@Service 注释的bean。 因为我使用过 STS，所以大部分文件都是自动创建的。我正在共享文件，请告诉我应该做哪些更改才能解决此问题。
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/root-context.xml</param-value>
</context-param>
<!-- Creates the Spring Container shared by all Servlets and Filters -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- Processes application requests -->
<servlet>
<servlet-name>appServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>appServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
servlet-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
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/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 -->
<annotation-driven />
<!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
<resources mapping="/resources/**" location="/resources/" />
<!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
<beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/" />
<beans:property name="suffix" value=".jsp" />
</beans:bean>
<context:component-scan base-package="com.example.annoproject.Controllers" />
<context:component-scan base-package="com.example.annoproject.Service" />
<context:component-scan base-package="com.example.annoproject.dao" />
</beans:beans>
root-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- Root Context: defines shared resources visible to all other web components -->
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/example_db" />
<property name="username" value="root" />
<property name="password" value="password" />
</bean>
<bean id = "jdbcTemplate" class = "org.springframework.jdbc.core.JdbcTemplate">
<constructor-arg ref = "dataSource"/>
</bean>
<bean id= "abstractService" class = "com.example.annoproject.service.AbstractService">
</bean>
</beans>
用户控制器
package com.example.annoproject.Controllers;
import com.example.annoproject.dao.UserDAOImpl;
import com.example.annoproject.model.User;
import com.example.annoproject.service.UserService;
@Controller
public class UserController {
@Autowired
UserService userService;
@RequestMapping(value = "/home", method = RequestMethod.GET)
public String signupPage(Model model){
userService.getUser("1");
return "home";
}
}
UserService.java
package com.example.annoproject.service;
import com.example.annoproject.dao.UserDAO;
import com.example.annoproject.model.User;
@Service("userService")
public class UserService {
@Autowired
UserDAO userDao;
public User getUser(String uid){
return userDao.getUser(uid);
}
}
UserDAOImpl.java
package com.example.annoproject.dao;
import com.example.annoproject.model.User;
@Repository("userDao")
public class UserDAOImpl implements UserDAO{
@Autowired
JdbcTemplate jdbcTemplate;
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
@Override
public User getUser(String id) {
String query = "SELECT * FROM empl where uid = ? ";
User user = jdbcTemplate.queryForObject(query, new Object[]{id}, new RowMapper<User>(){
@Override
public User mapRow(ResultSet rs, int rowNum) throws SQLException {
User user = new User();
user.setFirstName(rs.getString("empF"));
user.setLastName(rs.getString("emplL"));
return user;
}});
return user;
}
}
我尝试了很多东西。问题是在使用 @Controller UserController 时，尚未创建 userService bean。因此我们得到了例外。解决方案是在 root-context.xml 中定义 userService bean。但关键是我不想定义任何 bean，context <context:component-scan.. 应该已经解决了这个问题。由于 root-context 是第一个被读取的文件，如 web.xml - 部署描述符中所定义，我们需要更改那里的某些内容以便首先扫描包，并提前创建 userDao、userService、datasource 等 bean .但我无法巧妙地解决它。谁能告诉我标准做法是什么？我在这里错过了什么。谢谢。
顺便说一句，这里是 确切的例外：
WARN : org.springframework.web.context.support.XmlWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.example.annoproject.service.UserService com.example.annoproject.Controllers.UserController.userService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.example.annoproject.service.UserService] 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:298)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1148)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:293)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:191)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:636)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:934)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:602)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:521)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:462)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1241)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1154)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1041)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4944)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5230)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:714)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:581)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1683)
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)
您的上下文扫描包 com.example.annoproject.Service。但是你的服务在包裹com.example.annoproject.service.
遵守命名约定：包仅使用小写字母。你不会再犯这样的错误了。