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实现ApplicationContextAware - 当前ApplicationContext为空

javaspring
3
我正在编写一个Tomcat应用程序，作为一些内部服务的代理。
我已经将我的Spring项目从混合的XML和注释配置切换到基于Java和注释的配置。
在切换配置样式之前，该应用程序运行良好。现在我有两个问题。
1. 在执行两个过滤器中的init-methods时，ApplicationContext为null。当我调试我的应用程序时，我可以看到setApplicationContext方法被执行。
2. EntityManagerFactory没有注入到身份验证过滤器中（emf为null）。
启动Spring的代码如下：
import javax.servlet.FilterRegistration;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;
import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

public class MyAppSpringBoot implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext container) throws ServletException {
        initRootContext(container);
        initDispatcherContext(container);
        addFilters(container);
    }

    private void initDispatcherContext(ServletContext container) {
        AnnotationConfigWebApplicationContext servletContext = new AnnotationConfigWebApplicationContext();
        servletContext.register(MyAppDispatcherServletContext.class);
        ServletRegistration.Dynamic dispatcher
                = container.addServlet("myAppDispatcherServlet", new DispatcherServlet(servletContext));
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/");
    }

    private void initRootContext(ServletContext container) {
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.register(MyAppRootContext.class);
        container.addListener(new ContextLoaderListener(rootContext));
    }

    private void addFilters(ServletContext container) {
        FilterRegistration.Dynamic registration
                = container.addFilter("u3rAuthentication", UserDbAuthenticationFilter.class);
        registration.addMappingForUrlPatterns(null, false, "/entry/*");

        registration = container.addFilter("responseXmlFilter", ResponseTextXmlFilter.class);
        registration.addMappingForUrlPatterns(null, false, "/entry/*");
    }
}

根目录的代码：

import java.io.File;
import java.io.IOException;
import java.util.Properties;
import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;
import javax.xml.stream.XMLEventFactory;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;
import org.apache.tomcat.util.http.fileupload.disk.DiskFileItemFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.lookup.DataSourceLookupFailureException;
import org.springframework.jdbc.datasource.lookup.JndiDataSourceLookup;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.stereotype.Controller;

@Configuration
@ComponentScan(basePackages = "com.application", excludeFilters = @ComponentScan.Filter(Controller.class))
public class MyAppRootContext {

    @Bean
    public DataSource userDbJpaDataSource() throws DataSourceLookupFailureException {

        JndiDataSourceLookup lookup = new JndiDataSourceLookup();
        return lookup.getDataSource("jdbc/userDbPostgres");
    }

    @Bean
    public EntityManagerFactory entityManagerFactory() {
        //return Persistence.createEntityManagerFactory(MyAppConstants.U3R_PERSISTENCE_UNIT);
        LocalContainerEntityManagerFactoryBean fb = new LocalContainerEntityManagerFactoryBean();
        fb.setDataSource(userDbJpaDataSource());
        return fb.getNativeEntityManagerFactory();
    }

    @Bean
    public DiskFileItemFactory diskFileItemFactory() {
        DiskFileItemFactory factory = new DiskFileItemFactory();
        factory.setSizeThreshold(50_000 * 1024);
        factory.setRepository(new File("/WEB-INF/upload"));
        return factory;
    }

    @Bean
    public XMLOutputFactory xmlOutputFactory() {
        return XMLOutputFactory.newInstance();
    }

    @Bean
    public XMLInputFactory xmlInputFactory() {
        return XMLInputFactory.newInstance();
    }

    @Bean
    public XMLEventFactory xmlEventFactory() {
        return XMLEventFactory.newInstance();
    }

    @Bean
    public UrlPairing urlPairing() throws IOException {
        return new UrlPairing(myAppProperties().getProperty("myApp.UrlPairingFile"));
    }

    @Bean
    public Properties myAppProperties() throws IOException {
        Properties p = new Properties();
        p.load(MyAppRootContext.class.getResourceAsStream("/myAppConfig.properties"));
        return p;
    }

    @Bean
    public MyAppXmlFilterWords xmlFilterWords() throws IOException {
        MyAppXmlFilterWords words = MyAppXmlFilterWords.createFilterWords(myAppProperties().getProperty("myApp.xmlFilterWordFile"));
        return words;
    }

}

调度器servlet上下文的代码：

@Configuration
@ComponentScan(
        basePackages = "de.lgn.doorman",
        includeFilters = @ComponentScan.Filter(Controller.class)
)
public class MyAppDispatcherServletContext
{
    // all beans are defined in root context
    // correct ???
}

用于根认证过滤器的代码：

@Component
public class UserDbAuthenticationFilter implements Filter, ApplicationContextAware
{
    private static final Logger logger = LogManager.getLogger(UserDbAuthenticationFilter.class.getName());

    @Autowired
    EntityManagerFactory emf;

    private ApplicationContext appContext;

    @Override
    public void init(FilterConfig filterConfig)    
    {
        logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
        // *******************  NullPointerException here *******************
    }

    @Override
    public void destroy()
    { }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException
    {
        appContext = applicationContext;
    }

    /*
    @PostConstruct    // ***************** this annotation isn't working **********************
    public void filterInit() throws ServletException
    {
        logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
    }

    */
}

在我的控制器中，ApplicationContext 是正确的（非空）。
@Controller
@RequestMapping(value = "entry/**")
public class MyAppProxyController implements ApplicationContextAware
{

    @Autowired
    Properties myAppProperties;

    private ApplicationContext appContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException
    {
        appContext = applicationContext;
    }

    @PostConstruct
    public void init() throws ServletException   // this is working fine
    {
        logger.debug("Controller {} initialisiert. App-Context: {} {}", this.getClass().getName(),
                appContext.hashCode(), appContext);

        logger.debug("Beans im Zugriff von Controller:");
        for (String beanName : appContext.getBeanDefinitionNames())
        {
            logger.debug("          {}", beanName);
        }
        MyAppProxyController controller = (MyAppProxyController) appContext.getBean("myAppProxyController");
        logger.debug("controller-hash im Controller={}", controller.hashCode());
    }
}

Serge Ballesta的答案更新

我按照您的第二条指示进行了操作，但现在出现了以下异常：

13-Aug-2015 13:03:27.264 INFO [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.ApplicationContext.log Spring WebApplicationInitializers detected on classpath: [de.lgn.doorman.config.DmSpringBoot@c427b4f]
13-Aug-2015 13:03:27.655 INFO [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.ApplicationContext.log Initializing Spring root WebApplicationContext
13-Aug-2015 13:03:28.308 SEVERE [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.StandardContext.filterStart Exception starting filter responseXmlFilter
 org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'responseXmlFilter' is defined
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:698)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1174)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:283)

当我使用三次DelegatingFilterProxy时，我想知道我的自定义过滤器是如何连接到链中的。方法addFilter中的参数名称是否与bean名称相关联？请注意保留HTML标记。

更新Serge Ballesta答案的第二部分

下面是在引导代码中创建过滤器链的代码：

private void addFilters(ServletContext container)
{
    FilterRegistration.Dynamic registration =
            container.addFilter("userDbAuthenticationFilter", DelegatingFilterProxy.class);
    registration.addMappingForUrlPatterns(null, false, "/mapgate/*");

    registration = container.addFilter("prepareRequestFilter", DelegatingFilterProxy.class);
    registration.addMappingForUrlPatterns(null, false, "/mapgate/*");

    registration = container.addFilter("responseTextXmlFilter", DelegatingFilterProxy.class);
    registration.addMappingForUrlPatterns(null, false, "/mapgate/*");
}

这些是我在根上下文中的过滤器 bean 定义：

：

@Configuration
@ComponentScan(basePackages = "com.application", excludeFilters = @ComponentScan.Filter(Controller.class))
public class MyAppRootContext
{

    @Bean
    public UserDbAuthenticationFilter userDbAuthenticationFilter()
    {
        return new UserDbAuthenticationFilter();
    }

    @Bean
    public PrepareRequestFilter prepareRequestFilter()
    {
        return new PrepareRequestFilter();
    }

    @Bean
    public ResponseTextXmlFilter responseTextXmlFilter()
    {
        return new ResponseTextXmlFilter();
    }

    @Bean
    public DataSource userDbJpaDataSource() throws DataSourceLookupFailureException
    {

        JndiDataSourceLookup lookup = new JndiDataSourceLookup();
        return lookup.getDataSource("jdbc/userDbPostgres");
    }

    @Bean
    public EntityManagerFactory entityManagerFactory()
    {
        LocalContainerEntityManagerFactoryBean fb = new LocalContainerEntityManagerFactoryBean();
        fb.setDataSource(userDbJpaDataSource());
        return fb.getNativeEntityManagerFactory();
    }
}

过滤器仍然没有依赖注入。这是因为过滤器链是在引导阶段创建的，而bean是在根上下文中创建的吗？

Serge Ballesta答案的第3个更新

这是身份验证过滤器中的基本代码：

public class U3RAuthenticationFilter implements Filter, ApplicationContextAware
{
    private static final Logger logger = LogManager.getLogger(U3RAuthenticationFilter.class.getName());

    @Autowired(required = true)
    EntityManagerFactory entityManagerFactory;

    private ApplicationContext appContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException
    {
        appContext = applicationContext;
    }

    @PostConstruct
    public void filterInit() throws ServletException
    {
        logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
        logger.debug("Beans accessable by {}:", this.getClass().getName());
        for (String beanName : appContext.getBeanDefinitionNames())
        {
            logger.debug("          {}", beanName);
        }

        logger.debug("EntityManagerFactory: {}", (EntityManagerFactory)appContext.getBean("entityManagerFactory"));
    }
}

不会抛出任何异常。以下是日志记录：

20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1] controller-hash im Controller=1481031354
20150814-090718 INFO  [RMI TCP Connection(3)-127.0.0.1] Mapped "{[/mapgate/**],methods=[GET]}" onto protected void com.application.controller.MyAppProxyController.doGet(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
20150814-090718 INFO  [RMI TCP Connection(3)-127.0.0.1] Mapped "{[/mapgate/**],methods=[POST]}" onto protected void com.application.controller.MyAppProxyController.doPost(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) throws javax.servlet.ServletException,java.io.IOException
20150814-090718 INFO  [RMI TCP Connection(3)-127.0.0.1] Looking for @ControllerAdvice: WebApplicationContext for namespace 'myAppDispatcherServlet-servlet': startup date [Fri Aug 14 09:07:18 CEST 2015]; parent: Root WebApplicationContext
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1] Filter com.application.filter.UserDbAuthenticationFilter initialisiert. App-Context: 641348200 WebApplicationContext for namespace 'myAppDispatcherServlet-servlet': startup date [Fri Aug 14 09:07:18 CEST 2015]; parent: Root WebApplicationContext
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1] Beans accessable by com.application.filter.UserDbAuthenticationFilter:
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.internalConfigurationAnnotationProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.internalAutowiredAnnotationProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.internalRequiredAnnotationProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.internalCommonAnnotationProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.internalPersistenceAnnotationProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.event.internalEventListenerProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.event.internalEventListenerFactory
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           myAppDispatcherServletContext
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.context.annotation.ConfigurationClassPostProcessor.enhancedConfigurationProcessor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           myAppRootContext
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           myAppProxyController
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           requestMappingHandlerMapping
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcContentNegotiationManager
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           viewControllerHandlerMapping
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           beanNameHandlerMapping
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           resourceHandlerMapping
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcResourceUrlProvider
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           defaultServletHandlerMapping
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           requestMappingHandlerAdapter
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcConversionService
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcValidator
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcPathMatcher
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcUrlPathHelper
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcUriComponentsContributor
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           httpRequestHandlerAdapter
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           simpleControllerHandlerAdapter
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           handlerExceptionResolver
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           mvcViewResolver
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           userDbAuthenticationFilter
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           prepareRequestFilter
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           responseTextXmlFilter
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           myAppFilterChain
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           userDbJpaDataSource
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           <b>entityManagerFactory</b>
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           diskFileItemFactory
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           xmlOutputFactory
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           xmlInputFactory
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           xmlEventFactory
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           urlPairing
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           myAppProperties
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1]           xmlFilterWords
20150814-090718 DEBUG [RMI TCP Connection(3)-127.0.0.1] <b>EntityManagerFactory: null</b>
你的WebApplicationInitializer中有rootContext.register(DmRootContext.class);这行代码，而你的根上下文配置类为public class MyAppRootContext，是否打错了？ - Serge Ballesta
@SergeBallesta - 是的，这是一个打字错误，但不是在我的真实代码中。谢谢。 - JimHawkins
2个回答
3
罪魁祸首是MyAppSpringBoot的addFilter(..)方法。
如果您仔细查看这个LOC FilterRegistration.Dynamic registration = container.addFilter("u3rAuthentication", UserDbAuthenticationFilter.class);，就会发现尽管UserDbAuthenticationFilter已经在ServletContext中注册为过滤器，但它与spring上下文没有任何关联（因为直接注册了类而不是spring bean，这将解释ApplicationContext和emf的null引用）。
虽然同一个类UserDbAuthenticationFilter被spring扫描并注册为bean，但它并没有与ServletContext相关联（因为它没有被注册为过滤器，所以从未被调用，这就是您在调试时看到ApplicationContext被设置的地方）。
因此，同一个类UserDbAuthenticationFilter有两个实例，一个作为servlet的过滤器，另一个作为spring bean，它们之间没有关联/链接。
你需要的是一个既注册了servlet容器过滤器，同时也是spring bean的过滤器。使用GenericFilterBean即可。根据您的需求进行扩展，并注意下面的陷阱（来自API文档）。

这个通用过滤器基类不依赖于Spring ApplicationContext概念。过滤器通常不会加载自己的上下文，而是从Spring根应用程序上下文中访问服务bean，可以通过过滤器的ServletContext（请参见WebApplicationContextUtils）访问。

希望这能帮到您。如果您遇到任何问题/需要进一步帮助，请在评论中告诉我们。
1

由于应用程序上下文已正确注入到您的控制器中，我认为Spring已正确初始化。但是您的过滤器被声明为原始过滤器，而不是Spring bean，因此忽略了它们上面的Spring注释。

您有两种方法可以访问应用程序上下文：

  1. a raw filter (not Spring enabled) can get access to the root application context with WebApplicationContext WebApplicationContextUtils.getWebApplicationContext(ServletContext sc). For example, you could change your init method:

    @Override
public void init(FilterConfig filterConfig)    
{
    ServletContex sc = filterConfig.getServletContext();
    appContext = WebApplicationContextUtils.getWebApplicationContext(sc);
    logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
}

  2. you can also use a DelegatingFilterProxy to effectively use beans as filters:

    Change add filter to:

    private void addFilters(ServletContext container) {
    FilterRegistration.Dynamic registration
            = container.addFilter("u3rAuthentication", DelegatingFilterProxy.class);
    registration.addMappingForUrlPatterns(null, false, "/entry/*");

    registration = container.addFilter("responseXmlFilter", DelegatingFilterProxy.class);
    registration.addMappingForUrlPatterns(null, false, "/entry/*");
}

    add filter beans in your root context:

    @Bean
public UserDbAuthenticationFilter u3rAuthentication() { 
    return new UserDbAuthenticationFilter();
}

@Bean
public ResponseTextXmlFilter responseXmlFilter() { 
    return new ResponseTextXmlFilter();
}

    the init method will no longer be called, but this would work:

    @PostConstruct
public void filterInit() throws ServletException
{
    logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
}
你说得对，bean定义和addFilter调用中使用的名称有所不同。我已经纠正了这个问题，现在似乎过滤器链已经创建成功了。但是EntityManagerFactory没有被注入到UserDbAuthenticationFilter中。我会更新我的问题。 - JimHawkins
应该可以工作。我无法重现这个问题。仔细检查豆的创建和初始化调试日志，尝试使用@Autowired（required = true）EntityManagerFactory emf;强制出错，如果bean没有找到实体管理器工厂并分享堆栈跟踪。 - Serge Ballesta
我已经插入了@Autowired(required=true)并修改了用@PostConstruct注释的方法。请查看我的更新问题。 - JimHawkins
我接受你的答案，因为它帮了我很多。我发现在创建 EntityManagerFactory bean 的方法中犯了一个错误，所以这个方法返回了 NULL。但是我想知道为什么没有由 @Autowired(required=true) 引起的异常。也许我会创建另一个问题。 - JimHawkins
@Ulrich：我再次阅读了您的日志。过滤器是在servlet上下文中创建的，而应该在根上下文中创建：UserDbAuthenticationFilter initialisiert...WebApplicationContext for namespace 'myAppDispatcherServlet-servlet...parent: Root WebApplicationContext：您在根和应用程序上下文之间存在问题。您应该控制哪些bean在哪个上下文中创建。 - Serge Ballesta
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