【Java】spring BeanFactory getbean方法是怎么搜索出对应的类的

Z时代
2024-01-10
分类：技术分享

public interface BeanFactory {
Object getBean(String name) throws BeansException;
<T> T getBean(String name, Class<T> requiredType) throws BeansException;
<T> T getBean(Class<T> requiredType) throws BeansException;
......}

我用工具类：


import org.springframework.beans.BeansException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class SpringContextUtil implements ApplicationContextAware {
private static ApplicationContext applicationContext;     //Spring应用上下文环境
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
SpringContextUtil.applicationContext = applicationContext;
}
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
public static Object getBean(String name) throws BeansException {
return applicationContext.getBean(name);
}
public static <T> T getBean(Class<T> requiredType) {
return applicationContext.getBean(requiredType);
}
public static <T> T getBean(String name, Class<T> requiredType) throws BeansException {
return applicationContext.getBean(name, requiredType);
}
public static boolean containsBean(String name) {
return applicationContext.containsBean(name);
}
public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
return applicationContext.isSingleton(name);
}
@SuppressWarnings("rawtypes")
public static Class getType(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getType(name);
}
public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
return applicationContext.getAliases(name);
}}

去获取spring的xml文件中的对象的时候，他们分别是怎样在xml中搜索匹配的？
getBean(Strng name) 应该是通过id或name来匹配的吧？
getBean(Class<> clzss) 呢？
另外哪里有这些用法的说明？

回答

这个就是装配Bean的机制。第二个getBean(Class<> clzss)明显是按照类型获取，比方说，你要提取的Bean的类型是com.abc.def.test.service.LoginService
你只需要在这里给定参数是： getBean(com.abc.def.test.service.LoginService.class)
就可以得到一个LoginService的对象实例了

BeanFactory 上有 Class 到 bean_id 的 Map

【Java】spring BeanFactory getbean方法是怎么搜索出对应的类的