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前导：开始学习Spring核心思想，通过一个山寨精简版Spring代码结合学习。
内容：1. BeanDefinitionReader-配置读取者。 2. XmlBeanDefinitionReader-从XML中读取配置。 3. Resource-定位资源文件。这次将Bean的配置信息都放到了XML里，所以这里会有一个XML文件的读取，我们通过XmlBeanDefinitionReader将XML中的信息组装好成BeanDefinition放到一个Map里，这样我们就能真正做到像Spring那样靠配置文件来组装Bean。
重复的代码不再列出
BeanDefinition：
public class BeanDefinition {
private Object bean;
private Class beanClass;
private String beanClassName;
private PropertyValues propertyValues = new PropertyValues();
public BeanDefinition() {}
public Object getBean() {
return bean;
}
public void setBean(Object bean) {
this.bean = bean;
}
public Class getBeanClass() {
return beanClass;
}
public void setBeanClass(Class beanClass) {
this.beanClass = beanClass;
}
public String getBeanClassName() {
return beanClassName;
}
public void setBeanClassName(String beanClassName) {
this.beanClassName = beanClassName;
try {
this.beanClass = Class.forName(beanClassName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public PropertyValues getPropertyValues() {
return propertyValues;
}
public void setPropertyValues(PropertyValues propertyValues) {
this.propertyValues = propertyValues;
}
}
/**
* Resource是spring内部定位资源接口
* @author acer
*/
public interface Resource {
InputStream getInputStream() throws IOException;
}ResourceLoader：
public class ResourceLoader {
public Resource getResource(String location) {
URL resource = this.getClass().getClassLoader().getResource(location);
return new UrlResource(resource);
}
}UrlResource：
public class UrlResource implements Resource{
private final URL url;
public UrlResource(URL url) {
this.url = url;
}
@Override
public InputStream getInputStream() throws IOException {
URLConnection urlConnection = url.openConnection();
urlConnection.connect();
return urlConnection.getInputStream();
}
}
BeanDefinitionReader：
/**
* 从配置中读取BeanDefinitionReader
* @author acer
*
*/
public interface BeanDefinitionReader {
void loadBeanDefinitions(String location) throws Exception;
}AbstractBeanDefinitionReader：
/**
* 从配置中读取BeanDefinitionReader
* @author acer
*
*/
public abstract class AbstractBeanDefinitionReader implements BeanDefinitionReader{
private Map<String, BeanDefinition> registry;
private ResourceLoader resourceLoader;
protected AbstractBeanDefinitionReader(ResourceLoader resourceLoader) {
this.registry = new HashMap<String, BeanDefinition>();
this.resourceLoader = resourceLoader;
}
public Map<String, BeanDefinition> getRegistry() {
return this.registry;
}
public ResourceLoader getResourceLoader() {
return resourceLoader;
}
}
public class XmlBeanDefinitionReader extends AbstractBeanDefinitionReader{
public XmlBeanDefinitionReader(ResourceLoader resourceLoader) {
super(resourceLoader);
}
@Override
public void loadBeanDefinitions(String location) throws Exception {
InputStream inputStream = getResourceLoader().getResource(location).getInputStream();
doLoadBeanDefinitions(inputStream);
}
protected void doLoadBeanDefinitions(InputStream inputStream) throws Exception {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = factory.newDocumentBuilder();
Document doc = docBuilder.parse(inputStream);
//解析bean
registerBeanDefinitions(doc);
inputStream.close();
}
public void registerBeanDefinitions(Document doc) {
Element root = doc.getDocumentElement();
parseBeanDefinitions(root);
}
protected void parseBeanDefinitions(Element root) {
NodeList nl = root.getChildNodes();
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node instanceof Element) {
Element ele = (Element) node;
processBeanDefinition(ele);
}
}
}
protected void processBeanDefinition(Element ele) {
String name = ele.getAttribute("name");
String className = ele.getAttribute("class");
BeanDefinition beanDefinition = new BeanDefinition();
processProperty(ele, beanDefinition);
beanDefinition.setBeanClassName(className);
getRegistry().put(name, beanDefinition);
}
private void processProperty(Element ele, BeanDefinition beanDefinition) {
NodeList propertyNode = ele.getElementsByTagName("property");
for (int i = 0; i < propertyNode.getLength(); i++) {
Node node = propertyNode.item(i);
if (node instanceof Element) {
Element propertyEle = (Element) node;
String name = propertyEle.getAttribute("name");
String value = propertyEle.getAttribute("value");
beanDefinition.getPropertyValues().addPropertyValue(new PropertyValue(name, value));
}
}
}
}public class BeanFactoryTest {
@Test
public void test() throws Exception{
// 1.读取配置
XmlBeanDefinitionReader xmlBeanDefinitionReader = new XmlBeanDefinitionReader(new ResourceLoader());
xmlBeanDefinitionReader.loadBeanDefinitions("tinyioc.xml");
// 2.初始化BeanFactory并注册bean
BeanFactory beanFactory = new AutowireCapableBeanFactory();
for (Map.Entry<String, BeanDefinition> beanDefinitionEntry : xmlBeanDefinitionReader.getRegistry().entrySet())
beanFactory.registerBeanDefinition(beanDefinitionEntry.getKey(), beanDefinitionEntry.getValue());
// 3. 获取bean
HelloWorldService helloWorldService = (HelloWorldService) beanFactory.getBean("helloWorldService");
helloWorldService.helloWorld();
}
}
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">
<bean name="helloWorldService" class="step4.test.HelloWorldService">
<property name="text" value="Hello World! from step4!"></property>
</bean>
</beans>
Spring核心学习（4）从XML中读取BeanDefinition-将代码变成配置
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原文地址：http://blog.csdn.net/u011345136/article/details/45622593
