1 public class beanDefinition {   2    3     private String id;   4    5     private String className;   6    7  8     public beanDefinition(String id, String className) {   9         this.id = id;  10         this.className = className;  11   12     }13 14      public String getId() {  15         return id;  16     }17 18     public void setId(String id) {  19   20         this.id = id;  21   22     }  23   24   25     public String getClassName() {  26   27         return className;  28   29     }  30   31    32 33     public void setClassName(String className) {  34   35         this.className = className;  36   37     }  38   39    40   41 }    42   

自定义IoC容器WxyClassPathXMLApplicationContext ,该容器实现三个功能：

 （1） BeanDefinition的resource定位:readXML();

 （2） BeanDefinition的载入和解析 :readXML();

 （3） BeanDefinition在IoC容器中的注册 instanceBeans();

import java.net.URL;    import java.util.ArrayList;    import java.util.HashMap;    import java.util.List;    import java.util.Map;         import org.dom4j.Document;    import org.dom4j.Element;    import org.dom4j.XPath;    import org.dom4j.io.SAXReader;         import com.wxy.bean.BeanDefinition;    public class ClassPathXMLApplicationContext {             //存放BeanDefinition的列表，在beans.xml中定义的bean不止一个        private final List<BeanDefinition> beanDefinitions = new ArrayList<BeanDefinition>();        //将类名作为索引，将创建的Bean对象存入到Map中        private final Map<String, Object>  sigletons       = new HashMap<String, Object>();             public ClassPathXMLApplicationContext(String fileName) {            //读取xml配置文件            this.readXML(fileName);            //实例化bean            this.instanceBeans();        }             /**       * 读取XML配置文件，获取BeanDefinition内容，存入到beanDefinition列表中       * @param fileName xml配置文件名称       */             private void readXML(String fileName) {            SAXReader saxReader = new SAXReader();            Document document = null;            try {                //通过类加载器获取Resource资源路径,实现BeanDefinition的resource定位                URL xmlPath = this.getClass().getClassLoader().getResource(fileName);                //将xml读入到document中                document = saxReader.read(xmlPath);                Map<String, String> nsMap = new HashMap<String, String>();                //加入命名空间                nsMap.put("ns", "http://www.springframework.org/schema/beans");                //创建beans/bean查询路径,注意：路径前要注明命名空间，便于解析                XPath xsub = document.createXPath("//ns:beans/ns:bean");                //设置命名空间                xsub.setNamespaceURIs(nsMap);                //获取文档下的所有Bean节点                List<Element> beans = xsub.selectNodes(document);                for (Element element : beans) {                    //获取id属性值                    String id = element.attributeValue("id");                    //获取class属性值                    String clazz = element.attributeValue("class");                    BeanDefinition beanDefinition = new BeanDefinition(id, clazz);                    //将新创建的BeanDefinition赌侠ing放入到BeanDeifnitions中                    beanDefinitions.add(beanDefinition);                }            } catch (Exception e) {                System.out.println(e.toString());            }        }             /**       * 实例化bean,存入到sigletons中       */        private void instanceBeans() {            for (BeanDefinition beanDefinition : beanDefinitions) {                try {                    if (beanDefinition.getClassName() != null                        && !(beanDefinition.getClassName().isEmpty())) {                        //利用java反射机制，生成BeanDefinition实例，并将其注册到sigletons中                        sigletons.put(beanDefinition.getId(), Class.forName(                            beanDefinition.getClassName()).newInstance());                    }                } catch (Exception e) {                    e.printStackTrace();                }            }             }             /**       * 根据ID名获取实例bean       * return 返回一个Object对象，用户使用时，需要对获取的结果进行转换类型       */        public Object getBean(String beanName) {            return this.sigletons.get(beanName);        }    }  

 1 public class Test {   2    3     4    5     public static void main(String[] args) {   6    7         //IOC容器实例化   8    9        ClassPathXMLApplicationContext ctx = new WxyClassPathXMLApplicationContext("beans.xml");  10   11         //获取业务bean  12   13         PeopleServiceBean peopleService = (PeopleServiceBean) ctx.getBean("peopleService");  14   15         peopleService.save();  16   17     }  18   19    20   21 }