java spring Ioc(反射)机制

 1.java spring IOC正常写法，导入spring包

 ApplicationContext ctx = new
ClassPathXmlApplicationContext("applictionContext.xml");

  Teach s = (Teach) ctx.getBean(Teachid);

ClassPathXmlApplicationContext是spring包自带，我们是不是可以自己写一个类拟的功能呢，答案是肯定的。

2.自定义ClassPathXmlApplicationContext

这里需要导入解析xml包:jdom.
2.1BeanFactory.java(先定义一个工厂接口)

package self.spring;

public interface BeanFactory {

 public Object getBean(String beanId);

}

2.2ClassPathXmlApplicationContext.java

package self.spring;
 
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
import org.jdom.Element;
 
publicclass ClassPathXmlApplicationContextimplements
BeanFactory{
    private Map<String, Object>beans =
new HashMap<String, Object>();
 
    @Override
    public Object getBean(String beanId) {
       returnbeans.get(beanId);
    }
 
    @SuppressWarnings({"unchecked",
"unused" })
    public ClassPathXmlApplicationContext(String xmlfile) {
       org.jdom.input.SAXBuilder sb =new org.jdom.input.SAXBuilder();
       org.jdom.Document doc =
null;
       try {
           //构造xml文档对像
           doc = sb.build(this.getClass().getClassLoader()
                  .getResourceAsStream(xmlfile));
       } catch (Exception e) {
           System.out.println("docError:" +this.getClass()
+".java\t\n "
                  + e.toString());
       }
       org.jdom.Element root = doc.getRootElement();//根元素
 
       @SuppressWarnings("rawtypes")
       List list = root.getChildren("bean");
       for (int i = 0; i < list.size(); i++) {
           org.jdom.Element element = (Element) list.get(i);
           String id = element.getAttributeValue("id");
           if (null == id) {
              id = element.getAttributeValue("name");
           }
           String classes = element.getAttributeValue("class");
           Object o = null;
           try {
              o = Class.forName(classes).newInstance();
           } catch (Exception e) {
              System.out.println("Object oError:" +this.getClass()
                     +
".java\t\n" + e.toString());
           }
           System.out.println("id:" + id +"\t"
+ "classes:" + classes);
           beans.put(id, o);
           for (Element properyElement : ((List<Element>) element
                  .getChildren("property"))) {
 
              String name = properyElement.getAttributeValue("name");
              String bean = properyElement.getAttributeValue("bean");
              String value = properyElement.getAttributeValue("value");//这里暂时不写value,因为类型太多原因
              String factory_method = properyElement
                     .getAttributeValue("factory-method");//方法注入
              if (null == bean) {
                  bean = properyElement.getAttributeValue("ref");//
为了兼容spring官方属性
 
              }
 
              Object beanObject =beans.get(bean);
              String methodName ="set" + name.substring(0,1).toUpperCase()
                     + name.substring(1);
              System.out.print("method name= " + methodName);
 
              Class oo =
null;
              try {
                  oo = beanObject.getClass().getInterfaces()[0];//接口
              } catch (Exception e) {
                  oo = beanObject.getClass();//类
              }
              Method m =
null;
              try {//小写set后面方法setmethod
                  m = o.getClass().getMethod("set" + name, oo);
              } catch (NoSuchMethodException | SecurityException er) {
              }
 
              try {//正常方法
setMethod
                  m = o.getClass().getMethod(methodName, oo);
              } catch (NoSuchMethodException | SecurityException e) {
              }
              try {
                  m.invoke(o, beanObject);//执行方法
              } catch (Exception ex) {
                  System.out.println("Error:" +this.getClass()
                         +
".java\t\n" + ex.toString());
              }
           }
       }
    }
 
}

3.测试

 

package self.service;
 
import junit.framework.TestCase;
import self.model.Teacher;
import self.spring.BeanFactory;
import self.spring.ClassPathXmlApplicationContext;
 
 
publicclass TestTeacherextends TestCase {
    publicvoid testSave(){
       BeanFactory bean = 
new ClassPathXmlApplicationContext("teach_beans.xml");
       Teacher teacher=(Teacher) bean.getBean("teacher");
       teacher.setAge(30);
       teacher.setSid("No154545");
       teacher.setSname("自己写的IOC类");
       TeacherService t = (TeacherService) bean.getBean("teacherService");
//     teacher.setStudent(student);
       t.saveTeacher();
    }
}
 
运行结果：
id:teacher classes:self.model.Teacher

id:tDao classes:self.impl.TeacherDAOImpl

id:teacherService classes:self.service.TeacherService

method name = setTdaomethod name = setTeach教师证号：No154545　姓名：自己写的IOC类保存成功！
4.上述要用的类及xml源
TeacherDAO.java
package self.dao;
 
import self.model.Teacher;
publicinterface TeacherDAO {
    publicvoid saveTeacher(Teacher t);
 
}
 

 

TeacherDAOImpl.java

package self.impl;
 
import self.dao.TeacherDAO;
import self.model.Teacher;
 
publicclass TeacherDAOImplimplements TeacherDAO
{
    @Override
    publicvoid saveTeacher(Teacher t) {
       if(null != t){
           //数据库操作，省   
           System.out.println(t.toString()+"保存成功！");       
       }else{       
           System.out.println("Error:对像为空，不能保存！！！");
       }
    }
}
 

 

Teacher.java

package self.model;
 
publicclass Teacher {
    private Stringsid;
    private Stringsname;
    privateint
age;
    public String getSid() {
       returnsid;
    }
    publicvoid setSid(String sid) {
       this.sid = sid;
    }
    public String getSname() {
       returnsname;
    }
    publicvoid setSname(String sname) {
       this.sname = sname;
    }
    publicint getAge() {
       returnage;
    }
    publicvoid setAge(int
age) {
       this.age = age;
    }
    public String toString(){
       return"教师证号："+this.getSid()+"　姓名："+this.getSname();
      
    }
}
 
TeacherService.java
package self.service;
 
import self.dao.TeacherDAO;
import self.model.Teacher;
 
publicclass TeacherService {
    private TeacherDAOtdao;
    private Teacherteach;
    public TeacherDAO getTdao() {
       returntdao;
    }
    publicvoid setTdao(TeacherDAO tdao) {
       this.tdao = tdao;
    }
    public Teacher getTeach() {
       returnteach;
    }
    publicvoid setTeach(Teacher teach) {
       this.teach = teach;
    }
 
    publicvoid saveTeacher(){
      
       tdao.saveTeacher(teach);
    }
}
 
teach_beans.xml
<?xmlversion="1.0"encoding="UTF-8"?>
<beans>
    <beanid="teacher"class="self.model.Teacher"></bean>
    <beanid="tDao"class="self.impl.TeacherDAOImpl"></bean>
 
    <beanid="teacherService"class="self.service.TeacherService">
       <propertyname="tdao"ref="tDao"></property>
       <propertyname="teach"ref="teacher"></property>
    </bean>
</beans>