Spring_使用XML配置文件实现依赖注入

刺骨的言语ヽ痛彻心扉 2022-06-15 03:10 227阅读 0赞

package com.bjsxt.spring;
    
    public interface BeanFactory {
    	public Object getBean(String name);
    }

package com.bjsxt.spring;
    
    import java.lang.reflect.Method;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    import org.jdom2.Document;
    import org.jdom2.Element;
    import org.jdom2.input.SAXBuilder;
    
    public class ClassPathXmlApplicationContext implements BeanFactory {
    	private Map<String, Object> beans = new HashMap<String, Object>();
    
    	@SuppressWarnings("rawtypes")
    	public ClassPathXmlApplicationContext() throws Exception {
    		SAXBuilder sb = new SAXBuilder();
    		Document document = sb.build(ClassPathXmlApplicationContext.class
    				.getClassLoader().getResource("beans.xml"));// 获取文件
    		Element root = document.getRootElement();// 获取根元素
    		List list = root.getChildren();// 获取名字为bean的所有元素(子元素)
    		for (int i = 0; i < list.size(); i++) {
    			Element element = (Element) list.get(i);
    			String id = element.getAttributeValue("id");// u
    			String clazz = element.getAttributeValue("class");// UserDaoImpl
    			Object obj = Class.forName(clazz).newInstance();// 生成Class实例UserDaoImpl.class
    			System.out.println(id);
    			System.out.println(clazz);
    			beans.put(id, obj);// 添加至map集合
    
    			for (Element propertyElement : (List<Element>) element
    					.getChildren("property")) {
    				String name = propertyElement.getAttributeValue("name");// userDao
    				String bean = propertyElement.getAttributeValue("bean");// u
    				Object beanObject = beans.get(bean);// UserDaoImpl instance
    
    				String methodName = "set" + name.substring(0, 1).toUpperCase()
    						+ name.substring(1);// setUserDao(set,U,serDao)
    				System.out.println("method name = " + methodName);
    
    				Method m = obj.getClass().getMethod(methodName,
    						beanObject.getClass().getInterfaces()[0]);
    				m.invoke(obj, beanObject);
    			}
    		}
    	}
    
    	@Override
    	public Object getBean(String name) {
    		return beans.get(name);
    	}
    
    }

package com.bjsxt.service;
    
    import com.bjsxt.dao.UserDao;
    import com.bjsxt.model.User;
    
    public class UserService {
    	private UserDao userDao;
    
    	public UserDao getUserDao() {
    		return userDao;
    	}
    
    	public void setUserDao(UserDao userDao) {
    		this.userDao = userDao;
    	}
    
    	public void add(User user) {
    		this.userDao.save(user);
    	}
    }

package com.bjsxt.service;
    
    import org.junit.Test;
    
    import com.bjsxt.model.User;
    import com.bjsxt.spring.BeanFactory;
    import com.bjsxt.spring.ClassPathXmlApplicationContext;
    
    public class UserServiceTest {
    
    	@Test
    	public void testAdd() throws Exception {
    		BeanFactory factory = new ClassPathXmlApplicationContext();
    
    		UserService service = (UserService) factory.getBean("userService");
    		
    		User user = new User();
    		service.add(user);
    	}
    }