小编给大家分享一下SpringBoot怎么使用ApplicationContext获取bean对象,希望大家阅读完这篇文章之后都有所收获,下面让我们一起去探讨吧!
编写一个ApplicationContextFactory工厂类
public class ApplicationContextFactory{ private static ApplicationContext applicationContext = null; public static void setApplicationContext(ApplicationContext applicationContext) throws BeansException { applicationContext = applicationContext; } public static ApplicationContext getApplicationContext(){ return applicationContext; } }
在SpringBoot的启动类中设置ApplicationContext
public class Application { public static void main(String[] args) { ConfigurableApplicationContext app = SpringApplication.run(Application.class, args); ApplicationContextFactory.setApplicationContext(app); } }
通过ApplicationContextFactory获取SpringApplication从而获取bean对象
ApplicationContext applicationContext=ApplicationContextFactory.getApplicationContext(); Clazz clazz = applicationContext.getBean(Clazz.class);
DemoService
@Service public class DemoService { public void save(){ System.out.println("DemoService save"); } }
CommonClass
@Component public class CommonClass { @Resource private DemoService demoService; public void fun(){ System.out.println("fun"); demoService.save(); } }
Controller
@Resource private CommonClass commonClass; @ResponseBody @GetMapping("/fun") public void fun(){ commonClass.fun(); }
DemoService
@Service public class DemoService { public void save(){ System.out.println("DemoService save"); } }
CommonClass
public class CommonClass { @Resource private DemoService demoService; public void fun(){ System.out.println("fun"); demoService.save(); } }
Controller
@ResponseBody @GetMapping("/fun") public void fun(){ CommonClass commonClass = new CommonClass(); commonClass.fun(); }
比较两个代码发现后者与前者的区别:因后者的CommonClass 没有使用@Component标注,所以在Controller中不能才用注入方式生成CommonClass对象,而是才用new的方式生成了该对象。
这样一来,CommonClass 对象是手工创建,所以在它内部注入DemoService 对象的代码就错误了。
新建工具类
@Component public class ApplicationContextUtil implements ApplicationContextAware { private static ApplicationContext act; @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { act = applicationContext; } /** * 根据bean的名字获取工厂中对应的bean对象 * @param beanName * @return */ public static Object getBean(String beanName){ return act.getBean(beanName); } }
注:实际测试发现上面代码中的static不能省略
DemoService
@Service public class DemoService { public void save(){ System.out.println("DemoService save"); } }
CommonClass
public class CommonClass { @Resource private DemoService demoService; public void fun(){ DemoService demoService = (DemoService) ApplicationContextUtil.getBean("demoService"); System.out.println("fun"); demoService.save(); } }
此处不再采用注入的方式获取DemoService对象,而是通过工具类的方式
Controller
@ResponseBody @GetMapping("/fun") public void fun(){ CommonClass commonClass = new CommonClass(); commonClass.fun(); }
再次运行程序,一切正常
在SpringBoot整合Shiro的案例中,自定义Realm时,需要使用Service的对象。因为自定义的Realm类不能使用@Component之类的注解注释,所以使用本案例介绍的方法是正确的解决方案。尽管在1.6.0的shiro-all中下面代码可以正确运行:
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