【SpringBoot】在IOC之外的类中使用IOC内部的Bean

某些时候，某些类是不归IOC管的，如我们的一些Util，如何使用IOC中的Bean？

1、写一个SpringUtil类，该类用于操纵Spring的ApplicationContext

@Component的注解是需要的，该Util是要被Spring管理的。

@Component
public class SpringUtil implements ApplicationContextAware
{
    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException
    {
        if (SpringUtil.applicationContext == null)
        {
            SpringUtil.applicationContext = applicationContext;
        }
    }

    public static ApplicationContext getApplicationContext()
    {
        return applicationContext;
    }

    public static Object getBean(String name)
    {
        return getApplicationContext().getBean(name);
    }

    public static <T> T getBean(Class<T> clazz)
    {
        return getApplicationContext().getBean(clazz);
    }

    public static <T> T getBean(String name, Class<T> clazz)
    {
        return getApplicationContext().getBean(name, clazz);
    }
}

2、通过@Bean注解，返回一个Bean；

@Component
@Transactional
public class SysParamBusiness
{
    @Autowired
    private SysParamDao sysParamDao;

    public void modify(SysParamMO mo) throws LittleCatException
    {
        sysParamDao.modify(mo);
    }
    public String getValueByName(String name) throws LittleCatException
    {
        return sysParamDao.getValueByName(name).getValue();
    }
    public List<SysParamMO> getList() throws LittleCatException
    {
        return sysParamDao.getList();
    }

    @Bean(name="SysParamBusiness")
    public SysParamBusiness getSysParamBusiness()
    {
        return new SysParamBusiness();
    }
}

3、在我们自己的Util中使用

public class SysParamUtil
{
    public static String PARAM_NAME_MEMBER_ENABLE_DAYS = "member_enable_days";

    private static final SysParamBusiness sysParamBusiness = (SysParamBusiness) SpringUtil.getBean("SysParamBusiness");

    public static String getValueByName(String name) throws LittleCatException
    {
        return sysParamBusiness.getValueByName(name);
    }
}

注：

也可以这样使用（如果没有特殊逻辑，推荐使用这种方法）：

private static final SysParamBusiness sysParamBusiness = SpringUtil.getBean(SysParamBusiness.class);

这样，第二步就可以省略了。

原文地址：https://www.cnblogs.com/njlittlecat/p/9736341.html