当我尝试自动装配时，环境为空

Question

我正在尝试使用 Spring 的 Environment 抽象和 @PropertySource 在我的 @Configuration 注释类中加载和使用属性。但是，我在 PropertyConfig 类中将 Environment 设置为 null，因为它是从另一个 @Configuration 类 PersistenceConfig 访问的，该类使用它来访问属性。这是我的相关代码：

   @Configuration
  @PropertySource({ "classpath:/properties/email_${environment}.properties" })
  @PropertySource({ "classpath:/properties/appconfig.properties" })
  @PropertySource({ "classpath:/properties/ApplicationResources.properties" })
  @PropertySource({ "classpath:/properties/Database_${environment}.properties" })
  @PropertySource({ "classpath:/properties/log4j.properties" })
  @PropertySource({ "classpath:/properties/system.properties" })
  public class PropertiesConfig {

        @Autowired
        private Environment env;

        private static final PropertiesAccessor propertyAccessor = new                   PropertiesConfig().new PropertiesAccessor();

        public static String getPopertyValue(String property){
            return propertyAccessor.getPropertyValue(property);
        }

        private class PropertiesAccessor{

        public String getPropertyValue(String key){
             return env.getProperty(key);
        }
    }
 }

我的其他@Configuration 注释类 PersistenceConfig 如下：

  @Configuration
  @EnableTransactionManagement
  @ComponentScan(basePackages = {"com.template"})
  public class PersistenceConfig {

         @Bean
         public LocalSessionFactoryBean sessionFactory(){

                LocalSessionFactoryBean sessionFactory = new           LocalSessionFactoryBean();
            sessionFactory.setDataSource(dataSource());
            sessionFactory.setPackagesToScan(new String []                      {"com.template.domain" });
            sessionFactory.setHibernateProperties(hibernateProperties());
            return sessionFactory;


      }

     @Bean
     public BasicDataSource dataSource(){

            BasicDataSource dataSource = new BasicDataSource();
                       dataSource.setDriverClassName(PropertiesConfig.getPopertyValue("jdbc.driverClassName"));
            dataSource.setUrl(PropertiesConfig.getPopertyValue("jdbc.url"));
              dataSource.setUsername(PropertiesConfig.getPopertyValue("jdbc.user"));
                     dataSource.setPassword(PropertiesConfig.getPopertyValue("jdbc.pass"));

            return dataSource;
 }


 @Bean
 public HibernateTransactionManager transactionManager(){
    HibernateTransactionManager transactionManager = new HibernateTransactionManager();
    transactionManager.setSessionFactory(sessionFactory().getObject());
    return transactionManager;
}

Properties hibernateProperties(){
      return new Properties() {
          {
             setProperty("hibernate.hbm2ddl.auto", PropertiesConfig.getPopertyValue("hibernate.hbm2ddl.auto"));
             setProperty("hibernate.dialect", PropertiesConfig.getPopertyValue("hibernate.dialect"));
             setProperty("hibernate.globally_quoted_identifiers", "true");
          }
       };

}

}

但是，当 PersistenceConfig 的 dataSource() 方法尝试使用 PropertiesConfig.getPopertyValue("jdbc.driverClassName") 检索属性时，我得到 NullpointerException，因为 PropertyConfig 中 Environment 类型的 env 为空。

我在 WebApplicationInitializer 中按如下方式加载两个类：

 public class WebAppInitializer implements WebApplicationInitializer {

@Override
public void onStartup(ServletContext container) {
    // Create the 'root' Spring application context
    AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
    rootContext.register(PropertiesConfig.class,SecurityConfig.class,PersistenceConfig.class,ApplicationConfig.class);
    //rootContext.register(ApplicationConfig.class, PersistenceConfig.class, SecurityConfig.class); I have not added security yet

    // Manage the life-cycle of the root application context
    container.addListener(new ContextLoaderListener(rootContext));

    // Create the dispatcher servlet's Spring application context
    AnnotationConfigWebApplicationContext dispatcherServlet = new AnnotationConfigWebApplicationContext();
    dispatcherServlet.register(MvcConfig.class);

    // Register and map the dispatcher servlet
    ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher", new DispatcherServlet(dispatcherServlet));
    dispatcher.setLoadOnStartup(1);
    dispatcher.addMapping("/");

}

}

据我了解 PersistenceConfig 在 PropertyConfig 之前首先被加载。我对吗？还是有其他原因？如何使这项工作？

Answer 1

package com.template.config;

import javax.annotation.PostConstruct;

import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.context.annotation.Configuration;import     
org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;

@Configuration
@PropertySource({ "classpath:/properties/email_${environment}.properties" })
@PropertySource({ "classpath:/properties/appconfig.properties" })
@PropertySource({ "classpath:/properties/ApplicationResources.properties" })
@PropertySource({ "classpath:/properties/Database_${environment}.properties"    

})
@PropertySource({ "classpath:/properties/log4j.properties" })
@PropertySource({ "classpath:/properties/system.properties" })
public class PropertiesConfig {

   @Autowired
   private Environment env;

   private static Environment environment;

   @PostConstruct
   public void init(){
     environment = env;
     System.out.println(environment == env);
   }

   public static String getPopertyValue(String property){
      return environment.getProperty(property);
   }
}