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Merge pull request dianpoint#6 from dianpoint/initialize-project
Initialize project
2 parents 59d5795 + 3a5a275 commit 13da81a

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6 files changed

+180
-60
lines changed

6 files changed

+180
-60
lines changed

‎src/main/java/com/dianpoint/summer/beans/SimpleBeanFactory.java‎

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package com.dianpoint.summer.beans;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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/**
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* @author: congcong
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* @email: congccoder@gmail.com
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* @date: 2023/3/17 14:35
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*/
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public class SimpleBeanFactory implements BeanFactory {
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private List<BeanDefinition> beanDefinitions = new ArrayList<>();
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private List<String> beanNames = new ArrayList<>();
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private Map<String, Object> singletons = new HashMap<>();
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public SimpleBeanFactory() {}
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@Override
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public Object getBean(String beanName) throws NoSuchBeanDefinitionException {
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Object singleton = singletons.get(beanName);
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if (singleton == null) {
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// 此处单例创建未考虑DCL模式,后续优化
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int i = beanNames.indexOf(beanName);
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if (i == -1) {
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throw new NoSuchBeanDefinitionException();
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}
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BeanDefinition beanDefinition = beanDefinitions.get(i);
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try {
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singleton = Class.forName(beanDefinition.getClassName()).newInstance();
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} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
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e.printStackTrace();
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}
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singletons.put(beanDefinition.getId(), singleton);
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}
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return singleton;
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}
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@Override
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public void registerBeanDefinition(BeanDefinition beanDefinition) {
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this.beanDefinitions.add(beanDefinition);
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this.beanNames.add(beanDefinition.getId());
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}
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}

‎src/main/java/com/dianpoint/summer/beans/XmlBeanDefinitionReader.java‎

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package com.dianpoint.summer.beans;
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import com.dianpoint.summer.core.Resource;
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import org.dom4j.Element;
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/**
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* <p>
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* ClassPathXmlResource类中已经将XML读取为Element元素,通过Reader即可将Resource转化成BeanDefinition
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* </p>
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*
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* @author: congcong
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* @email: congccoder@gmail.com
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* @date: 2023/3/17 14:25
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*/
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public class XmlBeanDefinitionReader {
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private BeanFactory beanFactory;
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public XmlBeanDefinitionReader(BeanFactory beanFactory) {
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this.beanFactory = beanFactory;
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}
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/**
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* 从指定的XML文件加载bean定义
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*
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* @param resource
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* XML文件的资源描述
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*/
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public void loadBeanDefinitions(Resource resource) {
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while (resource.hasNext()) {
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Element element = (Element)resource.next();
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String id = element.attributeValue("id");
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String className = element.attributeValue("class");
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BeanDefinition beanDefinition = new BeanDefinition(id, className);
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this.beanFactory.registerBeanDefinition(beanDefinition);
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}
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}
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}

‎src/main/java/com/dianpoint/summer/context/ClassPathXmlApplicationContext.java‎

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@@ -1,76 +1,41 @@
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package com.dianpoint.summer.context;
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import com.dianpoint.summer.beans.BeanDefinition;
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import org.dom4j.Document;
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import org.dom4j.DocumentException;
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import org.dom4j.Element;
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import org.dom4j.io.SAXReader;
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import java.net.URL;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import com.dianpoint.summer.beans.BeanFactory;
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import com.dianpoint.summer.beans.NoSuchBeanDefinitionException;
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import com.dianpoint.summer.beans.SimpleBeanFactory;
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import com.dianpoint.summer.beans.XmlBeanDefinitionReader;
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import com.dianpoint.summer.core.ClassPathXmlResource;
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import com.dianpoint.summer.core.Resource;
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/**
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* @author: congcong
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* @email: congccoder@gmail.com
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* @date: 2023/3/17 11:59
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*/
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public class ClassPathXmlApplicationContext {
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private final List<BeanDefinition> beanDefinitions = new ArrayList<>();
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private final Map<String, Object> singletons = new HashMap<>();
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public class ClassPathXmlApplicationContext implements BeanFactory {
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private BeanFactory beanFactory;
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/**
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* 构造函数读取fileName中外部xml配置,将Bean的定义加载进入内存，并且初始化给BeanDefinition
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*
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* <ul>
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* <li>构造函数读取fileName中外部xml配置,将Bean的定义加载进入内存，并且初始化给BeanDefinition</li>
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* <li>context负责整合IOC容器的启动过程，读外部配置，解析Bean定义，创建BeanFactory</li>
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* </ul>
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*
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* @param fileName
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* 外部xml配置文件
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*/
3229
public ClassPathXmlApplicationContext(String fileName) {
33-
this.readXml(fileName);
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this.instanceBeans();
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}
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/**
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* 读取fileName对应xml配置文件。
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*
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* @param fileName
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* 资源文件地址
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*/
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private void readXml(String fileName) {
44-
SAXReader saxReader = new SAXReader();
45-
try {
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URL xmlPath = this.getClass().getClassLoader().getResource(fileName);
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Document document = saxReader.read(xmlPath);
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Element rootElement = document.getRootElement();
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// 遍历xml配置文件,读取每一个`<bean></bean>`配置
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for (Element element : rootElement.elements()) {
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String id = element.attributeValue("id");
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String className = element.attributeValue("class");
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// 初始化创建BeanDefinition
54-
BeanDefinition beanDefinition = new BeanDefinition(id, className);
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// 存入BeanDefinitions中
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beanDefinitions.add(beanDefinition);
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}
58-
} catch (DocumentException e) {
59-
e.printStackTrace();
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}
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}
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/**
64-
* 利用反射创建BeanDefinition,并将其存储singletons中
65-
*/
66-
private void instanceBeans() {
67-
for (BeanDefinition beanDefinition : beanDefinitions) {
68-
try {
69-
singletons.put(beanDefinition.getId(), Class.forName(beanDefinition.getClassName()).newInstance());
70-
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
71-
e.printStackTrace();
72-
}
73-
}
30+
// 加载外部xml文件定义为Resource资源
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Resource resource = new ClassPathXmlResource(fileName);
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BeanFactory factory = new SimpleBeanFactory();
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// 解析BeanDefinition定义
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XmlBeanDefinitionReader xmlBeanDefinitionReader = new XmlBeanDefinitionReader(factory);
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xmlBeanDefinitionReader.loadBeanDefinitions(resource);
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// 创建BeanFactory
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this.beanFactory = factory;
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}
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/**
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* beanName
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* @return beanName对应的class实例
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*/
83-
public Object getBean(String beanName) {
84-
return singletons.get(beanName);
48+
@Override
49+
public Object getBean(String beanName) throws NoSuchBeanDefinitionException {
50+
return this.beanFactory.getBean(beanName);
51+
}
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@Override
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public void registerBeanDefinition(BeanDefinition beanDefinition) {
55+
this.beanFactory.registerBeanDefinition(beanDefinition);
8556
}
8657
}

‎src/main/java/com/dianpoint/summer/core/ClassPathXmlResource.java‎

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package com.dianpoint.summer.core;
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import org.dom4j.Document;
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import org.dom4j.DocumentException;
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import org.dom4j.Element;
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import org.dom4j.io.SAXReader;
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import java.net.URL;
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import java.util.Iterator;
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/**
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* <p>
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* ClassPathXmlResource处理xml类型资源
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* </p>
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*
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* @author: congcong
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* @email: congccoder@gmail.com
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* @date: 2023/3/17 14:19
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*/
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public class ClassPathXmlResource implements Resource {
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private Document document;
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private Element rootElement;
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private Iterator<Element> elementIterator;
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public ClassPathXmlResource(String fileName) {
27+
SAXReader saxReader = new SAXReader();
28+
URL xmlPath = this.getClass().getClassLoader().getResource(fileName);
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try {
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this.document = saxReader.read(xmlPath);
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this.rootElement = document.getRootElement();
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this.elementIterator = rootElement.elementIterator();
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} catch (DocumentException e) {
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e.printStackTrace();
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}
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}
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@Override
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public boolean hasNext() {
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return this.elementIterator.hasNext();
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}
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@Override
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public Object next() {
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return this.elementIterator.next();
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}
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}

‎src/main/java/com/dianpoint/summer/core/Resource.java‎

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package com.dianpoint.summer.core;
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import java.util.Iterator;
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/**
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* <p>
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* Resource定义为资源,将外部所有配置信息均理解为资源,使用Resource进行抽象处理
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* </p>
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*
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* @author: congcong
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* @email: congccoder@gmail.com
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* @date: 2023/3/17 14:20
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*/
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public interface Resource extends Iterator<Object> {}

‎src/test/java/com/dianpoint/summer/test/SimpleIOCTest.java‎

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package com.dianpoint.summer.test;
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import com.dianpoint.summer.beans.NoSuchBeanDefinitionException;
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import com.dianpoint.summer.context.ClassPathXmlApplicationContext;
45
import com.dianpoint.summer.test.service.SimpleService;
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@@ -10,7 +11,8 @@
1011
*/
1112
public class SimpleIOCTest {
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13-
public static void main(String[] args) {
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public static void main(String[] args) throws NoSuchBeanDefinitionException {
1416
ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
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SimpleService simpleService = (SimpleService)applicationContext.getBean("simpleService");
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simpleService.sayHello();

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