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Spring 容器管理 反射生成的类

Spring 容器管理 反射生成的类

作者: 程序员小白成长记 | 来源:发表于2021-10-12 13:52 被阅读0次

    问题 & 背景

    【问题描述】在开发中通过反射生成了类,反射类中注入的成员变量为null

    【问题原因】因为反射生成的类没有交由springboot管理

    【问题解决】反射生成类后,需要交由spring容器管理

    代码

    如果不交由spring容器管理,打断点发现testServicenull,执行testService.test()报空指针异常

    public class TestCompute implements ICompute {
        @Autowired
        TestService testService;
        public void compute() {
            testService.test();
        }
    }
    
    Class<?> cls = null;
    try {
        cls = Class.forName(computeRule.toString());
        // ICompute iCompute = (ICompute) cls.newInstance();
        ICompute iCompute = (ICompute) SpringUtil.getBean(cls);
        // 获取计算规则实例为空
        if (iCompute == null) {
            log.debug("====> class: {} is not fond", computeRule);
            throw new ServiceUserTagException("class " + computeRule + " is not found");
        }
        return iCompute;
    } catch (Exception e) {
        log.error("class not found: {}, e: {}", computeRule, e);
        throw new ServiceUserTagException("class not found " + computeRule);
    }
    
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.stereotype.Component;
    
    @Slf4j
    @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;
            }
            log.info("ApplicationContext配置成功,applicationContext对象:"+SpringUtil.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);
        }
    }
    

    参考

    【1】springBoot @Autowired注入对象为空原因总结:https://blog.csdn.net/sunjinjuan/article/details/87255551

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