java - 自动连线环境为空

Question

我在将环境连接到我的 Spring 项目时遇到问题。在这个班

@Configuration
@ComponentScan(basePackages = "my.pack.offer.*")
@PropertySource("classpath:OfferService.properties")
public class PropertiesUtil {
    @Autowired
    private Environment environment;



    @Bean
    public String load(String propertyName)
    {
        return environment.getRequiredProperty(propertyName);
    }
}

环境始终为空。

Answer 1

自动装配发生load()在调用之后（出于某种原因）。

一种解决方法是实现EnvironmentAware并依赖 Spring 调用setEnvironment()方法：

@Configuration
@ComponentScan(basePackages = "my.pack.offer.*")
@PropertySource("classpath:OfferService.properties")
public class PropertiesUtil implements EnvironmentAware {
    private Environment environment;

    @Override
    public void setEnvironment(final Environment environment) {
        this.environment = environment;
    }

    @Bean
    public String load(String propertyName)
    {
        return environment.getRequiredProperty(propertyName);
    }
}

Answer 2

更改@Autowired（@Resource来自 javax.annotation）并使其public例如：

@Configuration
@PropertySource("classpath:database.properties")
public class HibernateConfigurer {

    @Resource
    public Environment env;

    @Bean
    public DataSource dataSource() {
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName(env.getProperty("database.driverClassName"));
        dataSource.setUrl(env.getProperty("database.url"));
        dataSource.setUsername(env.getProperty("database.username"));
        dataSource.setPassword(env.getProperty("database.password"));
        dataSource.setValidationQuery(env.getProperty("database.validationQuery"));

        return dataSource;
    }
}

而且您必须以这种方式在 WebApplicationInitializer 中注册您的配置器类

AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
context.register(ApplicationConfigurer.class); //ApplicationConfigurer imports HibernateConfigurer

它对我有用！您可能想检查我制作的测试项目。

Answer 3

我用构造函数注入解决了同样的问题：

@Configuration
@PropertySource("classpath:my.properties")
public class MyConfig {
    private Environment environment;

    public MyConfig(Environment environment) {
        this.environment = environment
    }

    @Bean
    public MyBean myBean() {
        return new MyBean(environment.getRequiredProperty("srv.name"))
    }
}

后来，我将其简化为这种形式（以使属性正确注入）：

@Configuration
@PropertySource("classpath:my.properties")
public class MyConfig {
    private String serviceName;

    public MyConfig(Environment ignored) {
        /* No-op */
    }

    @Value("${srv.name}")
    public void setServiceName(String serviceName) {
        this.serviceName = serviceName;
    }

    @Bean
    public MyBean myBean() {
        return new MyBean(requireNonNull(serviceName)); // NPE without environment in constructor
    }
}

Answer 4

请将此代码放在您尝试自动装配环境的类中

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

它解决了我的问题。下面我给你我的课。

@Configuration
@EnableTransactionManagement
public class DatabaseConfig {   
/**
 * DataSource definition for database connection. Settings are read from the
 * application.properties file (using the env object).
 */
@Bean
public DataSource dataSource() {

    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(env.getProperty("db.driver"));
    dataSource.setUrl(env.getProperty("db.url"));
    dataSource.setUsername(env.getProperty("db.username"));
    dataSource.setPassword(env.getProperty("db.password"));
    return dataSource;
}

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

  @Autowired
  private Environment env;

}