java - 将数据从 Controller 传递到服务层时的 Autowiring 依赖关系

Question

我正在制作一个 Spring Web 应用程序，没有任何 Hibernate/数据库连接。我只想将数据从 Controller 层传递到包含应用程序“内容”的 Service。

每当我尝试添加行时:

@Autowired
private CalcArffService calcArffService;

进入 Controller ，抛出异常:

org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [app.service.CalcArffService] 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)}

当我尝试访问所有页面时。

如何解决这个问题？

<小时/>

以下是必要的文件:

CalcController.java

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
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 app.domain.BreastCancer;
import app.service.CalcArffService;

@Controller
@RequestMapping(value = "calc")
public class CalcController {

  protected final Log logger = LogFactory.getLog(getClass());

  @ModelAttribute("breastCancer")
  public BreastCancer createModel() {
    return new BreastCancer();
  }

  @Autowired
  private CalcArffService calcArffService; // causes trouble tbh

  @RequestMapping(method = RequestMethod.GET)
  public String showCalcPage(ModelMap model) {
    /* stuff */
    return "calc";
  }

  @RequestMapping(method = RequestMethod.POST)
  public String showResultsPage(
      @ModelAttribute("breastCancer") BreastCancer breastCancer,
      BindingResult result) {
    logger.info(breastCancer.toString());
    //calcArffService.evaluate(breastCancer);
    if (result.hasErrors()) {
      return "calc";
    } else {
      return "redirect:calc/results";
    }
  }
}

CalcArffService.java

import app.domain.BreastCancer;

public interface CalcArffService {

  /**
   * 
   * @param breastCancer
   */
  public void evaluate(BreastCancer breastCancer);

}

CalcArffServiceImpl.java

@SuppressWarnings("deprecation")
@Service("calcArffService")
public class CalcArffServiceImpl implements CalcArffService {

  protected final Log logger = LogFactory.getLog(getClass());

  @Autowired
  private CalcArffService calcArffService;

  /**
   * {@inheritDoc}
   */
  @Override
  public void evaluate(BreastCancer breastCancer) {
    logger.info(breastCancer.toString());
  }

}

web.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
      xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"
      id="WebApp_ID" version="2.5">
      <display-name>bosom</display-name>
      <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
      </welcome-file-list>
      <servlet>
        <servlet-name>spring</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
      </servlet>
      <servlet-mapping>
        <servlet-name>spring</servlet-name>
        <url-pattern>/</url-pattern>
      </servlet-mapping>
    </web-app>

spring-dispatcher-servlet.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" xmlns:context="http://www.springframework.org/schema/context"
      xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd">

      <context:component-scan base-package="app.controller" />
      <context:component-scan base-package="app.service" />
      <context:component-scan base-package="app.service.impl" />

      <bean id="viewResolver"
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass"
          value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
      </bean>

      <!--Enables many annotations and searches for @Controller annotated methods 
        etc.. -->
      <context:annotation-config />

      <!--JSR-303 (Bean validation) support will be detected on classpath and 
        enabled automatically -->
      <mvc:annotation-driven />

      <!--This tag allows for mapping the DispatcherServlet to "/" (all extensions 
        etc) -->
      <mvc:default-servlet-handler />

      <mvc:annotation-driven />
      <mvc:resources location="/css/" mapping="/css/**" />
      <mvc:resources location="/images/" mapping="/images/**" />
      <mvc:resources location="/js/" mapping="/js/**" />

    </beans>

完整堆栈跟踪

 SEVERE: Allocate exception for servlet spring
    org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [app.service.CalcArffService] 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:988)
      at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:858)
      at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:770)
      at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:489)
      at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
      at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:286)
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1146)
      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$1.getObject(AbstractBeanFactory.java:296)
      at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
      at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293)
      at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
      at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:628)
      at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
      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:599)
      at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
      at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:518)
      at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:459)
      at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
      at javax.servlet.GenericServlet.init(GenericServlet.java:212)
      at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1173)
      at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:809)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:129)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
      at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
      at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
      at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
      at java.lang.Thread.run(Unknown Source)

Answer 1

设置组件扫描器来扫描服务包中的 Bean。在 spring-dispatcher-servlet.xml 中添加:

<context:component-scan base-package="app.service" />

为了使依赖注入(inject)起作用，被注入(inject)的组件和接收注入(inject)的组件都必须是 bean。服务和 bean 都必须通过组件扫描来发现。