Java @@component、@service e.t.c注释类中的自动连接字段为空

我正在尝试使用@AnnotationDrivenConfig。目前，@component、@service e.t.c注释类中的@Autowired字段为空。Maven似乎无法为我的项目解析@AnnotationDrivenConfig依赖项。通常会在SpringXML中处理这个问题。对于Spring4.1.5的java配置设置，我如何解决这个问题

以下是堆栈跟踪：

DEBUG: org.springframework.web.servlet.DispatcherServlet - Handler execution resulted in exception java.lang.NullPointerException
at com.reviewsystem.crazytenants.application.controllers.interceptors.SiteSwitcher.preHandle(MySwitcher.java:23)
at org.springframework.web.servlet.HandlerExecutionChain.applyPreHandle(HandlerExecutionChain.java:134)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

代码如下：

MySwitcher.java

package x.y.z

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import x.y.z.MySwitcherHandler;

@Component
public class MySwitcher extends HandlerInterceptorAdapter {

    public MySwitcher(){
        super();
    }

    public boolean preHandle( HttpServletRequest request, HttpServletResponse response, Object handler ) throws Exception {
        mySwitcherHandler.setup( request, response );
        return true;
    }

    @Autowired
    private MySwitcherHandler mySwitcherHandler;
}

MySwitcherHandler.java

package x.y.z

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.mobile.device.Device;
import org.springframework.mobile.device.site.SitePreference;
import org.springframework.stereotype.Service;

@Service
public class MySwitcherHandler {

    public MySwitcherHandler(){}

    public MySwitcherHandler( HttpServletRequest request, HttpServletResponse response ){
        setup( request, response );
    }

    public void setup( HttpServletRequest request, HttpServletResponse response ){
        System.out.println( "running MySiteSwitcherHandler.setup( HttpServletRequest request, HttpServletResponse response )" );    
    }

    public void setup( SitePreference sitePreference, Device device ){
        System.out.println( "running MySiteSwitcherHandler.setup( SitePreference sitePreference, Device device )" );
    }

    public void update( SitePreference sitePreference, Device device ){
        System.out.println( "running MySiteSwitcherHandler.update( SitePreference sitePreference, Device device )" );
    }
}

AppConfig.java

package x.y.z;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

//@AnnotationDrivenConfig
@ComponentScan( basePackages = {"x.y.z."} )
@Configuration
@EnableWebMvc
public class AppConfig extends WebMvcConfigurerAdapter {

    @Override
    public void configureDefaultServletHandling( DefaultServletHandlerConfigurer configurer ) {
        configurer.enable();
    }

    @Bean 
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    @Override
    public void addArgumentResolvers( List<HandlerMethodArgumentResolver> argumentResolvers ) {
        argumentResolvers.add( new ServletWebArgumentResolverAdapter( new DeviceWebArgumentResolver() ));
        argumentResolvers.add( new ServletWebArgumentResolverAdapter( new SitePreferenceWebArgumentResolver() ));
    }

    @Override
    public void addInterceptors( InterceptorRegistry registry ) {
        registry.addInterceptor( new DeviceResolverHandlerInterceptor() );
        registry.addInterceptor( new SitePreferenceHandlerInterceptor() );
        registry.addInterceptor( new MySwitcher() );
    }

    /* ... */
}

包装x.y.z；
导入org.springframework.context.annotation.Bean；
导入org.springframework.context.annotation.ComponentScan；
导入org.springframework.context.annotation.Configuration；
导入org.springframework.context.support.propertysourcesplaceplaceconfigurer；
导入org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer；
导入org.springframework.web.servlet.config.annotation.EnableWebMvc；
导入org.springframework.web.servlet.config.annotation.WebMVCConfigureAdapter；
//@注释驱动图
@组件扫描（基本包={“x.y.z.”）
@配置
@EnableWebMvc
公共类AppConfig扩展WebMVCConfigureAdapter{
@凌驾
公共无效配置DefaultServletHandling（DefaultServletHandlerConfigurer-configurer）{
configurer.enable（）；
}
@豆子
公共静态属性资源占位符配置器属性资源占位符配置器（）{
返回新属性资源占位符配置器（）；
}
@凌驾
public void addArgumentResolver（列出ArgumentResolver）{
添加（新的ServletWebArgumentResolveRadepter（新设备WebArgumentResolver（））；
添加（新的ServletWebArgumentResolveRadepter（新的站点首选项WebArgumentResolver（））；
}
@凌驾
公共无效附加接收器（侦听器注册表）{
addInterceptor（新的DeviceResolverHandlerInterceptor（））；
addInterceptor（新SitePreferenceHandlerInterceptor（））；
addInterceptor（newmyswitcher（））；
}
/* ... */
}

对于要由Spring注入的对象，它必须是Springbean。替换

@Override
public void addInterceptors( InterceptorRegistry registry ) {
    registry.addInterceptor( new DeviceResolverHandlerInterceptor() );
    registry.addInterceptor( new SitePreferenceHandlerInterceptor() );
    registry.addInterceptor( new MySwitcher() );
}

借

---

至少需要代码和堆栈跟踪。@Chrylis，我现在还添加了堆栈跟踪和代码。感谢的副本。建议的重复链接中的问题是因为MileageFeeController.mileageFee方法有一个MileageFeeCalculator变量，该变量是在Spring IOC容器中声明的。请再看一看。Thanks@APC非常感谢您为问题提供额外编辑谢谢，@JB Nizet。这很有帮助。最后，我向AppConfig类添加了一个自动连接的私有SiteSwitcher SiteSwitcher字段，并删除了实例化的SiteSwitcher参数。

public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(deviceResolverHandlerInterceptor());
    registry.addInterceptor(sitePreferenceHandlerInterceptor());
    registry.addInterceptor(mySwitcher());
}

@Bean
public DeviceResolverHandlerInterceptor deviceResolverHandlerInterceptor() {
    return new DeviceResolverHandlerInterceptor();
}

@Bean
public SitePreferenceHandlerInterceptor sitePreferenceHandlerInterceptor() {
    return new SitePreferenceHandlerInterceptor();
}

@Bean
public MySwitcher mySwitcher() {
    return new MySwitcher();
}