Spring第三弹—–编码剖析Spring管理Bean的原理
先附一下编写的Spring容器的执行结果：
代码如下：
模拟的Spring容器类：
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package zmcSpring;
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;
/*
* 简单模拟Spring容器
*/
public class ZmcClassPathXMLApplicationContext {
private List<BeanDefinition> beanDefines = new ArrayList<BeanDefinition>();
private Map<String,Object> sigletons = new HashMap<String,Object>();
public ZmcClassPathXMLApplicationContext(String fileName){
this.readXML(fileName);
this.instanceBeans();
}
/*
* 完成bean的实例化
*/
private void instanceBeans(){
for(BeanDefinition beanDefinition : beanDefines){
try {
sigletons.put(beanDefinition.getId(), Class.forName(beanDefinition.getClassName()).newInstance());
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
/*
* 读取XMl配置文件
* @param filename
*/
public void readXML(String fileName){
SAXReader saxReader = new SAXReader();
Document document = null;
try{
URL xmlpath = this.getClass().getClassLoader().getResource(fileName);
document = saxReader.read(xmlpath);
Map<String,String> nsMap = new HashMap<String,String>();
nsMap.put("ns", "http://www.springframework.org/schema/beans");//加入命名空间
XPath xsub = document.createXPath("//ns:beans/ns:bean");//创建beans/bean查询路径
xsub.setNamespaceURIs(nsMap);//设置命名空间
List<Element> beans = xsub.selectNodes(document);
for(Element element : beans){
String id = element.attributeValue("id");
String clazz = element.attributeValue("class");
BeanDefinition beanDefinition = new BeanDefinition(id,clazz);
beanDefines.add(beanDefinition);
}
}
catch (Exception e){
e.printStackTrace();
}
}
/*
* 获取bean实例
*/
public Object getBean(String beanName){
return this.sigletons.get(beanName);
}
}
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存取bean信息的类：
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package zmcSpring;
public class BeanDefinition {
private String id;
private String className;
public BeanDefinition() {
super();
}
public BeanDefinition(String id, String className) {
super();
this.id = id;
this.className = className;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getClassName() {
return className;
}
public void setClassName(String className) {
this.className = className;
}
}
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测试类：
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package Test;
import org.junit.BeforeClass;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import zmcSpring.ZmcClassPathXMLApplicationContext;
import zmcjk.PersonService;
public class SpringD {
@BeforeClass
public static void setUpBeforeClass() throws Exception {
}
@Test
public void T() {
ZmcClassPathXMLApplicationContext zmc = new ZmcClassPathXMLApplicationContext("beans.xml");
PersonService ps = (PersonService) zmc.getBean("personService");
ps.save();
/*ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
PersonService ps = (PersonService) ctx.getBean("personService");
ps.save();*/
}
}
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PS:配置文件及bean类都在上篇博客。
