首先分析。
1： 肯定要利用dom4j读取xml配置文件，将所有的bean的配置信息读取出来
2： 利用反射技术，实例化所有的bean
3： 写注解处理器， 利用注解和内省实现依赖对象的注入。
4： 利用XML中<property>信息，通过内省beanUtils实现基本数据类型的注入
实现：
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package cn.gbx.example;import java.beans.IntrospectionException;import java.beans.Introspector;import java.beans.PropertyDescriptor;import java.io.File;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.net.URL;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.commons.beanutils.ConvertUtils;import org.dom4j.Document;import org.dom4j.Element;import org.dom4j.XPath;import org.dom4j.io.SAXReader;public
class MyClassPathXmlApplicationContext { private
List<DefBean> defBeans = new
ArrayList<DefBean>(); private
Map<String, Object> singletons = new
HashMap<String, Object>(); public
MyClassPathXmlApplicationContext(String filename) { this.readXML(filename); this.instanceBean(); this.injectAnotation(); this.injectXML(); } //注入基本类型的属性 private
void injectXML() { //枚举bean for
(DefBean defBean : defBeans) { Object bean = singletons.get(defBean.getId()); if
(bean != null) { //枚举该bean的Property看有没有基本数据类型的注入 for
(DefProperty defProperty : defBean.getDefPropertys()) { if
(defProperty.getValue() != null){ try
{ PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors(); for
(PropertyDescriptor p : ps) { if
(p.getName().equals(defProperty.getName())) { Method setter = p.getWriteMethod(); //保证有set方法 if
(setter != null) { Object value = ConvertUtils.convert(defProperty.getValue(), p.getPropertyType()); setter.setAccessible(true); setter.invoke(bean, value); } break; } } } catch
(Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } } } //注解处理器 private
void injectAnotation() { //枚举实例化的bean for
(String key : singletons.keySet()) { Object bean = singletons.get(key); if
(bean != null) { /* * 检查setter方法 */ try
{ PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors(); //枚举每个bean的属性 for
(PropertyDescriptor p : ps) { Method setter = p.getWriteMethod(); Object value = null; //存在set方法， 并且有setter上边有Resource注解 if
(setter != null
&& setter.isAnnotationPresent(GbxResource.class)){ GbxResource gbxResource = setter.getAnnotation(GbxResource.class); //若有name 则按name查找 if
(gbxResource.name() != null
&& !"".equals(gbxResource.name())) { value = singletons.get(gbxResource.name()); } else
{ //若没有，先安名字查找， 再按数据类型查找 value = singletons.get(p.getName()); if
(value == null) { for
(String key2 : this.singletons.keySet()) { if
(p.getPropertyType().isAssignableFrom(this.singletons.get(key2).getClass())) { value = this.singletons.get(key2); break; } } } } setter.setAccessible(true); setter.invoke(bean, value); } } } catch
(Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } /* * 检查字段 */ Field[] fileds = bean.getClass().getDeclaredFields(); for
(Field field : fileds) { if
(field.isAnnotationPresent(GbxResource.class)) { GbxResource gbxResource = field.getAnnotation(GbxResource.class); Object value = null; if
(gbxResource.name() != null
&& !"".equals(gbxResource.name())) { value = this.singletons.get(gbxResource.name()); } else
{ value = this.singletons.get(field.getName()); if
(value == null) { for
(String key2 : this.singletons.keySet()) { if
(field.getType().isAssignableFrom(this.singletons.get(key2).getClass())) { value = this.singletons.get(key2); break; } } } } field.setAccessible(true); try
{ field.set(bean, value); } catch
(IllegalAccessException e) { e.printStackTrace(); } } } } } } //实例化bean对象 private
void instanceBean() { for
(DefBean bean : defBeans) { System.out.println(bean.getId() + " : "
+ bean.getClassName()); if
(bean.getClassName() != null
&& !"".equals(bean.getClassName())) { try
{ singletons.put(bean.getId(), Class.forName(bean.getClassName()).newInstance()); } catch
(Exception e) { e.printStackTrace(); } } } } //读取xml文件 private
void readXML(String filename) { SAXReader reader = new
SAXReader(); Document document = null; URL xmlPath = this.getClass().getClassLoader().getResource(filename); try
{ //的到document document = reader.read(xmlPath); //设置命名空间 Map<String, String> nsMap = new
HashMap<String, String>(); //创建查询路径 XPath xPath = document.createXPath("//ns:beans/ns:bean"); xPath.setNamespaceURIs(nsMap); List<Element> beans = xPath.selectNodes(document); DefBean defBean = null; for
(Element e : beans) { String id = e.attributeValue("id"); String className = e.attributeValue("class"); defBean = new
DefBean(id, className); XPath xPath2 = e.createXPath("ns:property"); xPath2.setNamespaceURIs(nsMap); List<Element> propertys = xPath2.selectNodes(e); DefProperty defProperty = null; for
(Element e2 : propertys) { String name = e2.attributeValue("name"); String ref
= e2.attributeValue("ref"); String value = e2.attributeValue("value"); defProperty = new
DefProperty(name, ref, value); defBean.getDefPropertys().add(defProperty); } defBeans.add(defBean); } } catch
(Exception e) { e.printStackTrace(); } } public
Object getBean(String key) { return
singletons.get(key); }} |
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package cn.gbx.serviceimpl;import java.util.ArrayList;import java.util.HashMap;import java.util.HashSet;import java.util.List;import java.util.Map;import java.util.Properties;import java.util.Set;import javax.annotation.Resource;import org.springframework.beans.factory.annotation.Autowired;import cn.gbx.daoimpl.PersonDao;import cn.gbx.example.GbxResource;import cn.gbx.service.PersonService;public
class PersonServiceImpl implements PersonService { @GbxResource private
PersonDao personDao; private
String name; public
void save() { personDao.save(); System.out.println("Name = "
+ name); System.out.println("service层的 save方法"); } public
void setPersonDao(PersonDao personDao) { this.personDao = personDao; } public
String getName() { return
name; } public
void setName(String name) { this.name = name; } public
PersonDao getPersonDao() { return
personDao; } } |
注解：
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package cn.gbx.example;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Retention(RetentionPolicy.RUNTIME)@Target({ElementType.METHOD, ElementType.FIELD})public
@interface
GbxResource { public
String name() default
"";} |
编码实现Spring 利用@Resource注解实现bean的注入，xml实现基本数据类型的注入
原文：http://www.cnblogs.com/E-star/p/3560070.html