Don'；t work@Autowired注释线程异常；“主要”；java.lang.NullPointerException

我正在使用spring数据，我使用@Bean、@Entity和Main.java创建配置类，但在运行project时，我遇到异常：

Exception in thread "main" java.lang.NullPointerException

@Autowired

注释无效

Main.java

public class Main {

    @Autowired
    private static TodoRepository todoRepository;

    public static void main(String[] args) {
        Todo todo = new Todo();
        todo.setId(1l);
        todo.setTitle("title");
        System.out.println(todoRepository); //null
        todoRepository.save(todo);          //Exception in thread "main" java.lang.NullPointerException
    }
}

上下文类

@Configuration
@EnableJpaRepositories(basePackages = {"repository"},
        entityManagerFactoryRef = "entityManagerFactory",
        transactionManagerRef = "transactionManager")
@EnableTransactionManagement
@PropertySource("classpath:app.properties")
public class PersistenceContext {

    public PersistenceContext() {
    }

    /**
     * The method that configures the datasource bean
     * */

    @Resource
    private Environment env;

    @Bean(destroyMethod = "close")
    DataSource dataSource() {
        HikariConfig dataSourceConfig = new HikariConfig();
        dataSourceConfig.setJdbcUrl(env.getRequiredProperty("db.url"));
        dataSourceConfig.setDriverClassName(env.getRequiredProperty("db.driver"));
        dataSourceConfig.setUsername(env.getRequiredProperty("db.username"));
        dataSourceConfig.setPassword(env.getRequiredProperty("db.password"));
        return new HikariDataSource(dataSourceConfig);
    }

    /**
     * The method that configures the entity manager factory
     * */
    @Bean
    LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, Environment env) {
        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource);
        entityManagerFactoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
        entityManagerFactoryBean.setPackagesToScan("entity");

        Properties jpaProperties = new Properties();

        jpaProperties.put("hibernate.dialect", env.getRequiredProperty("hibernate.dialect"));
        jpaProperties.put("hibernate.hbm2ddl.auto", env.getRequiredProperty("hibernate.hbm2ddl.auto"));
        jpaProperties.put("hibernate.show_sql", env.getRequiredProperty("hibernate.show_sql"));
        jpaProperties.put("hibernate.format_sql", env.getRequiredProperty("hibernate.format_sql"));

        entityManagerFactoryBean.setJpaProperties(jpaProperties);

        return entityManagerFactoryBean;
    }

    /**
     * The method that configures the transaction manager
     * */
    @Bean
    JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory);
        return transactionManager;
    }
}

public interface TodoRepository extends CrudRepository<Todo, Long> {

}

存储库

@Configuration
@EnableJpaRepositories(basePackages = {"repository"},
        entityManagerFactoryRef = "entityManagerFactory",
        transactionManagerRef = "transactionManager")
@EnableTransactionManagement
@PropertySource("classpath:app.properties")
public class PersistenceContext {

    public PersistenceContext() {
    }

    /**
     * The method that configures the datasource bean
     * */

    @Resource
    private Environment env;

    @Bean(destroyMethod = "close")
    DataSource dataSource() {
        HikariConfig dataSourceConfig = new HikariConfig();
        dataSourceConfig.setJdbcUrl(env.getRequiredProperty("db.url"));
        dataSourceConfig.setDriverClassName(env.getRequiredProperty("db.driver"));
        dataSourceConfig.setUsername(env.getRequiredProperty("db.username"));
        dataSourceConfig.setPassword(env.getRequiredProperty("db.password"));
        return new HikariDataSource(dataSourceConfig);
    }

    /**
     * The method that configures the entity manager factory
     * */
    @Bean
    LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, Environment env) {
        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource);
        entityManagerFactoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
        entityManagerFactoryBean.setPackagesToScan("entity");

        Properties jpaProperties = new Properties();

        jpaProperties.put("hibernate.dialect", env.getRequiredProperty("hibernate.dialect"));
        jpaProperties.put("hibernate.hbm2ddl.auto", env.getRequiredProperty("hibernate.hbm2ddl.auto"));
        jpaProperties.put("hibernate.show_sql", env.getRequiredProperty("hibernate.show_sql"));
        jpaProperties.put("hibernate.format_sql", env.getRequiredProperty("hibernate.format_sql"));

        entityManagerFactoryBean.setJpaProperties(jpaProperties);

        return entityManagerFactoryBean;
    }

    /**
     * The method that configures the transaction manager
     * */
    @Bean
    JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory);
        return transactionManager;
    }
}

public interface TodoRepository extends CrudRepository<Todo, Long> {

}

---

您的主类不是托管Springbean。您需要创建ApplicationContext，请参见以下内容：

public class Main {
    public static void main(String[] args) {public static void main(String[] args) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(PersistenceContext.class);
        TodoRepository todoRepository = ctx.getBean(TodoRepository.class);
        Todo todo = new Todo();
        todo.setId(1l);
        todo.setTitle("title");
        System.out.println(todoRepository); // not null
        todoRepository.save(todo);
    }
}

---

您的主类不是托管Springbean。您需要创建ApplicationContext，请参见以下内容：

public class Main {
    public static void main(String[] args) {public static void main(String[] args) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(PersistenceContext.class);
        TodoRepository todoRepository = ctx.getBean(TodoRepository.class);
        Todo todo = new Todo();
        todo.setId(1l);
        todo.setTitle("title");
        System.out.println(todoRepository); // not null
        todoRepository.save(todo);
    }
}

---

我使用的是

ApplicationContext

版本，我需要使用

@Autowired

版本，我需要使用

@Autowired

的具体工具。我用

ApplicationContext

编写过代码。我用

ApplicationContext

编写过版本，我需要用

@Autowired

编写版本，我需要用

@Autowired

具体实现。我使用过

ApplicationContext

编写代码。

TodoRepository

的实现在哪里，您希望自动连线什么？没有实现

TodoRepository

并且我想使用overide方法，我想获取

TodoRepository

对象以用于overide方法，直到不知道您正在尝试做什么，但是删除这个

静态

关键字。无法自动关联静态成员。不要键入某个

static

以便可以在

main

中使用它。

TodoRepository

的实现在哪里，您希望自动连接什么？没有实现

TodoRepository

，我想使用overide方法，我想获取

TodoRepository

对象，以便在IDE方法上使用，直到不知道您要执行的操作为止，但请删除该

static

关键字。无法自动关联静态成员。不要键入某个

static

，只是为了在

main

中使用它。