我正在尝试使用 @Configuration 注释来连接我的应用程序，但我一直在其中一个初始化程序中收到 NullPointerException 异常，因为它引用的 bean 尚未初始化(我认为)。我尝试在 web.xml 中仅指定“root”配置类，并尝试进行包扫描，但似乎都不起作用。

对大代码转储感到抱歉。我试图生成一组更简单的类来重现该问题，但是当然，当我这样做时，一切正常。这是我的类(class)(省略了导入):

数据源配置.java:

@Configuration
public class DataSourceConfig {

    public DataSourceConfig() {
        System.err.println("DataSourceConfig constructed...");
    }

    @Bean
    public DataSource dataSource() {
        BasicDataSource bean = new BasicDataSource();
        bean.setDriverClassName("com.mysql.jdbc.Driver");
        bean.setUrl("jdbc:mysql://localhost:3306/observation");
        bean.setUsername("observation");
        bean.setPassword("*******");
        bean.setInitialSize(1);
        bean.setMaxActive(5);
        bean.setTestOnBorrow(true);
        System.err.println("dataSource bean initialized: " + bean.toString());
        return bean;
    }
}

@Configuration
@Import(DataSourceConfig.class)
public class HibernateConfig {

    public HibernateConfig() {
        System.err.println("HibernateConfig constructing...");
    }

    @Autowired
    private DataSourceConfig dataSourceConfig;

    @Bean
    protected NamingStrategy namingStrategy() {
        return new ImprovedNamingStrategy();
    }

    private AnnotationSessionFactoryBean sessionFactoryBean = null;

    @Bean
    @DependsOn("dataSourceConfig")
    public AnnotationSessionFactoryBean sessionFactory() {
        if (sessionFactoryBean == null) {
            sessionFactoryBean = new AnnotationSessionFactoryBean();
NPE Here--> sessionFactoryBean.setDataSource(dataSourceConfig.dataSource()); 
            sessionFactoryBean.setSchemaUpdate(true);
            sessionFactoryBean.setNamingStrategy(namingStrategy());
            sessionFactoryBean.setPackagesToScan(new String[] {
                    "com.newco.observations.domain",
                    "com.newco.observations.domain.*" });
            Properties props = new Properties();
            props.setProperty("hibernate.default_schema", "observation");
            props.setProperty("hibernate.dialect",
                    "org.hibernate.dialect.MySQLDialect");
            props.setProperty("hibernate.show_sql", "true");
            sessionFactoryBean.setHibernateProperties(props);
            System.err.println("sessionFactory initialized");
        }
        return sessionFactoryBean;
    }

    @Bean
    @DependsOn("dataSourceConfig")
    public JdbcTemplate jdbcTemplate() {
        return new JdbcTemplate(dataSourceConfig.dataSource());
    }

    @Bean
    @DependsOn("sessionFactory")
    public ResourceTransactionManager txManager() {
        HibernateTransactionManager bean = new HibernateTransactionManager();
        bean.setSessionFactory((SessionFactory) sessionFactory().getObject());
        return bean;
    }

    @Bean
    @DependsOn("sessionFactory")
    public HibernateTemplate hibernateTemplate() {
        return new HibernateTemplate((SessionFactory) sessionFactory()
                .getObject());
    }
}

@Configuration
@Import(HibernateConfig.class)
public class DaoConfig {

    public DaoConfig()
    {
        System.err.println("DaoConfig constructing...");
    }

    private @Autowired HibernateConfig hibernateConfig;

    @Bean
    @DependsOn("hibernateTemplate")
    public PhenomenonGroupDao phenomenonGroupDao()
    {
        PhenomenonGroupDaoImpl bean = new PhenomenonGroupDaoImpl();
        bean.setHibernateTemplate(hibernateConfig.hibernateTemplate());
        return bean;
    }

    @Bean
    @DependsOn("hibernateTemplate")
    public PhenomenonDao phenomenonDao()
    {
        PhenomenonDaoImpl bean = new PhenomenonDaoImpl();
        bean.setHibernateTemplate(hibernateConfig.hibernateTemplate());
        return bean;
    }

    @Bean
    @DependsOn("hibernateTemplate")
    public DiscretePhenomenonDao discretePhenomenonDao()
    {
        DiscretePhenomenonDaoImpl bean = new DiscretePhenomenonDaoImpl();
        bean.setHibernateTemplate(hibernateConfig.hibernateTemplate());
        return bean;
    }


}

最佳答案

问题，我相信是在这里:

@Autowired
private DataSourceConfig dataSourceConfig;

@Autowired
private DataSource dataSource;

@Autowired 
private HibernateConfig hibernateConfig;

@Autowired 
private HibernateTemplate hibernateTemplate;

关于java - 如何确保使用 Spring @Configuration 注释初始化依赖配置？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/3261082/