包扫描

README.md

@@ -1,6 +1,8 @@
 # <img src="assets/spring-framework.png" width="80" height="80"> mini-spring
 [![Build Status](https://img.shields.io/badge/build-passing-brightgreen)](https://github.com/DerekYRC/mini-spring)
 [![License](https://img.shields.io/badge/license-Apache%202-4EB1BA.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
+[![Stars](https://img.shields.io/github/stars/DerekYRC/mini-spring)](https://img.shields.io/github/stars/DerekYRC/mini-spring)
+[![Forks](https://img.shields.io/github/forks/DerekYRC/mini-spring)](https://img.shields.io/github/forks/DerekYRC/mini-spring)
 
 ## About
 * [中文版](./README_CN.md)
@@ -38,16 +40,22 @@ If this project can help you, please give a **STAR, thank you!!!**
 
 #### Expanding 
 * [PropertyPlaceholderConfigurer](#PropertyPlaceholderConfigurer)
-* [Type conversion](#类型转换)
 * [Package scan](#包扫描)
-* [Autowired annotation](#基于注解的依赖注入Autowired)
+* [@Autowired and @Value annotation](#基于注解@Autowired和@Value的依赖注入)
+* [Type conversion](#类型转换)
 
 #### Advanced
 * [Solve the problem of circular dependencies](#解决循环依赖问题)
 
 ## Usage
 Each function point corresponds to a branch. Switch to the branch corresponding to the function point to see the new function. The incremental change point is described in the [changelog.md](https://github.com/DerekYRC/mini-spring/blob/main/changelog.md) file.
 
+## Contributing
+Any contributions you make are greatly appreciated.
+
+## Contact
+Please feel free to ask me any questions related to mini-spring and other technologies. My email is **[email protected]**. 
+
 ## Reference
 - [《Spring源码深度解析》](https://book.douban.com/subject/25866350/)
 - [《精通Spring 4.x》](https://book.douban.com/subject/26952826/)

README_CN.md

@@ -1,6 +1,8 @@
 # <img src="assets/spring-framework.png" width="80" height="80"> mini-spring
 [![Build Status](https://img.shields.io/badge/build-passing-brightgreen)](https://github.com/DerekYRC/mini-spring)
 [![License](https://img.shields.io/badge/license-Apache%202-4EB1BA.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
+[![Stars](https://img.shields.io/github/stars/DerekYRC/mini-spring)](https://img.shields.io/github/stars/DerekYRC/mini-spring)
+[![Forks](https://img.shields.io/github/forks/DerekYRC/mini-spring)](https://img.shields.io/github/forks/DerekYRC/mini-spring)
 
 ## 关于
 * [English version](./README.md)
@@ -38,16 +40,23 @@
 
 #### 扩展篇
 * [PropertyPlaceholderConfigurer](#PropertyPlaceholderConfigurer)
-* [类型转换](#类型转换)
 * [包扫描](#包扫描)
-* [基于注解的依赖注入Autowired](#基于注解的依赖注入Autowired)
+* [基于注解@Autowired和@Value的依赖注入](#基于注解@Autowired和@Value的依赖注入)
+* [类型转换](#类型转换)
 
 #### 高级篇
 * [解决循环依赖问题](#解决循环依赖问题)
 
 ## 使用方法
 每个功能点对应一个分支，切换到功能点对应的分支了解新增的功能，增量改动点在[changelog.md](https://github.com/DerekYRC/mini-spring/blob/main/changelog.md)文件中描述。
 
+## 贡献
+欢迎Pull Request
+
+## 联系我
+欢迎探讨跟mini-spring和其他技术相关的问题，个人邮箱：**[email protected]**
+
+
 ## 参考
 - [《Spring源码深度解析》](https://book.douban.com/subject/25866350/)
 - [《精通Spring 4.x》](https://book.douban.com/subject/26952826/)

changelog.md

@@ -976,7 +976,47 @@ public class PropertyPlaceholderConfigurerTest {
 }
 ```
 
+## 包扫描
+> 分支：package-scan
 
+结合bean的生命周期，包扫描只不过是扫描特定注解的类，提取类的相关信息组装成BeanDefinition注册到容器中。
+
+在XmlBeanDefinitionReader中解析**```<context:component-scan />```**标签，扫描类组装BeanDefinition然后注册到容器中的操作在ClassPathBeanDefinitionScanner#doScan中实现。
+
+测试：
+```
+@Component
+public class Car {
+
+}
+```
+package-scan.xml
+```
+<?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:context="http://www.springframework.org/schema/context"
+       xsi:schemaLocation="http://www.springframework.org/schema/beans
+	         http://www.springframework.org/schema/beans/spring-beans.xsd
+		 http://www.springframework.org/schema/context
+		 http://www.springframework.org/schema/context/spring-context-4.0.xsd">
+
+    <context:component-scan base-package="org.springframework.test.bean"/>
+
+</beans>
+```
+```
+public class PackageScanTest {
+
+	@Test
+	public void testScanPackage() throws Exception {
+		ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:package-scan.xml");
+
+		Car car = applicationContext.getBean("car", Car.class);
+		assertThat(car).isNotNull();
+	}
+}
+```
 
 
 

src/main/java/org/springframework/beans/factory/config/BeanDefinition.java

@@ -2,6 +2,8 @@
 
 import org.springframework.beans.PropertyValues;
 
+import java.util.Objects;
+
 /**
  * BeanDefinition实例保存bean的信息，包括class类型、方法构造参数、bean属性、bean的scope等，此处简化只包含class类型和bean属性
  *
@@ -82,4 +84,17 @@ public String getDestroyMethodName() {
 	public void setDestroyMethodName(String destroyMethodName) {
 		this.destroyMethodName = destroyMethodName;
 	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) return true;
+		if (o == null || getClass() != o.getClass()) return false;
+		BeanDefinition that = (BeanDefinition) o;
+		return beanClass.equals(that.beanClass);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(beanClass);
+	}
 }

src/main/java/org/springframework/beans/factory/xml/XmlBeanDefinitionReader.java

@@ -12,6 +12,7 @@
 import org.springframework.beans.factory.config.BeanReference;
 import org.springframework.beans.factory.support.AbstractBeanDefinitionReader;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 
@@ -37,6 +38,8 @@ public class XmlBeanDefinitionReader extends AbstractBeanDefinitionReader {
 	public static final String INIT_METHOD_ATTRIBUTE = "init-method";
 	public static final String DESTROY_METHOD_ATTRIBUTE = "destroy-method";
 	public static final String SCOPE_ATTRIBUTE = "scope";
+	public static final String BASE_PACKAGE_ATTRIBUTE = "base-package";
+	public static final String COMPONENT_SCAN_ELEMENT = "component-scan";
 
 	public XmlBeanDefinitionReader(BeanDefinitionRegistry registry) {
 		super(registry);
@@ -71,8 +74,19 @@ protected void doLoadBeanDefinitions(InputStream inputStream) throws DocumentExc
 		SAXReader reader = new SAXReader();
 		Document document = reader.read(inputStream);
 
-		Element beans = document.getRootElement();
-		List<Element> beanList = beans.elements(BEAN_ELEMENT);
+		Element root = document.getRootElement();
+
+		//解析context:component-scan标签并扫描指定包中的类，提取类信息，组装成BeanDefinition
+		Element componentScan = root.element(COMPONENT_SCAN_ELEMENT);
+		if (componentScan != null) {
+			String scanPath = componentScan.attributeValue(BASE_PACKAGE_ATTRIBUTE);
+			if (StrUtil.isEmpty(scanPath)) {
+				throw new BeansException("The value of base-package attribute can not be empty or null");
+			}
+			scanPackage(scanPath);
+		}
+
+		List<Element> beanList = root.elements(BEAN_ELEMENT);
 		for (Element bean : beanList) {
 			String beanId = bean.attributeValue(ID_ATTRIBUTE);
 			String beanName = bean.attributeValue(NAME_ATTRIBUTE);
@@ -126,4 +140,15 @@ protected void doLoadBeanDefinitions(InputStream inputStream) throws DocumentExc
 			getRegistry().registerBeanDefinition(beanName, beanDefinition);
 		}
 	}
+
+	/**
+	 * 扫描注解Component的类，提取信息，组装成BeanDefinition
+	 *
+	 * @param scanPath
+	 */
+	private void scanPackage(String scanPath) {
+		String[] basePackages = StrUtil.splitToArray(scanPath, ',');
+		ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(getRegistry());
+		scanner.doScan(basePackages);
+	}
 }

src/main/java/org/springframework/context/annotation/ClassPathBeanDefinitionScanner.java

@@ -0,0 +1,71 @@
+package org.springframework.context.annotation;
+
+import cn.hutool.core.util.StrUtil;
+import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.stereotype.Component;
+
+import java.util.Set;
+
+/**
+ * @author derekyi
+ * @date 2020/12/26
+ */
+public class ClassPathBeanDefinitionScanner extends ClassPathScanningCandidateComponentProvider {
+
+	private BeanDefinitionRegistry registry;
+
+	public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry) {
+		this.registry = registry;
+	}
+
+	public void doScan(String... basePackages) {
+		for (String basePackage : basePackages) {
+			Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
+			for (BeanDefinition candidate : candidates) {
+				// 解析bean的作用域
+				String beanScope = resolveBeanScope(candidate);
+				if (StrUtil.isNotEmpty(beanScope)) {
+					candidate.setScope(beanScope);
+				}
+				//生成bean的名称
+				String beanName = determineBeanName(candidate);
+				//注册BeanDefinition
+				registry.registerBeanDefinition(beanName, candidate);
+			}
+		}
+	}
+
+	/**
+	 * 获取bean的作用域
+	 *
+	 * @param beanDefinition
+	 * @return
+	 */
+	private String resolveBeanScope(BeanDefinition beanDefinition) {
+		Class<?> beanClass = beanDefinition.getBeanClass();
+		Scope scope = beanClass.getAnnotation(Scope.class);
+		if (scope != null) {
+			return scope.value();
+		}
+
+		return StrUtil.EMPTY;
+	}
+
+
+	/**
+	 * 生成bean的名称
+	 *
+	 * @param beanDefinition
+	 * @return
+	 */
+	private String determineBeanName(BeanDefinition beanDefinition) {
+		Class<?> beanClass = beanDefinition.getBeanClass();
+		Component component = beanClass.getAnnotation(Component.class);
+		String value = component.value();
+		if (StrUtil.isEmpty(value)) {
+			value = StrUtil.lowerFirst(beanClass.getSimpleName());
+		}
+		return value;
+	}
+}

src/main/java/org/springframework/context/annotation/ClassPathScanningCandidateComponentProvider.java

@@ -0,0 +1,26 @@
+package org.springframework.context.annotation;
+
+import cn.hutool.core.util.ClassUtil;
+import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.stereotype.Component;
+
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+/**
+ * @author derekyi
+ * @date 2020/12/26
+ */
+public class ClassPathScanningCandidateComponentProvider {
+
+	public Set<BeanDefinition> findCandidateComponents(String basePackage) {
+		Set<BeanDefinition> candidates = new LinkedHashSet<BeanDefinition>();
+		// 扫描有org.springframework.stereotype.Component注解的类
+		Set<Class<?>> classes = ClassUtil.scanPackageByAnnotation(basePackage, Component.class);
+		for (Class<?> clazz : classes) {
+			BeanDefinition beanDefinition = new BeanDefinition(clazz);
+			candidates.add(beanDefinition);
+		}
+		return candidates;
+	}
+}

src/main/java/org/springframework/context/annotation/Scope.java

@@ -0,0 +1,15 @@
+package org.springframework.context.annotation;
+
+import java.lang.annotation.*;
+
+/**
+ * @author derekyi
+ * @date 2020/12/26
+ */
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface Scope {
+
+	String value() default "singleton";
+}

src/main/java/org/springframework/stereotype/Component.java

@@ -0,0 +1,15 @@
+package org.springframework.stereotype;
+
+import java.lang.annotation.*;
+
+/**
+ * @author derekyi
+ * @date 2020/12/26
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface Component {
+
+	String value() default "";
+}

src/test/java/org/springframework/test/bean/Car.java

@@ -1,9 +1,12 @@
 package org.springframework.test.bean;
 
+import org.springframework.stereotype.Component;
+
 /**
  * @author derekyi
  * @date 2020/11/24
  */
+@Component
 public class Car {
 
 	private String brand;

src/test/java/org/springframework/test/ioc/PackageScanTest.java

@@ -0,0 +1,22 @@
+package org.springframework.test.ioc;
+
+import org.junit.Test;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.test.bean.Car;
+
+import static org.assertj.core.api.Java6Assertions.assertThat;
+
+/**
+ * @author derekyi
+ * @date 2020/12/26
+ */
+public class PackageScanTest {
+
+	@Test
+	public void testScanPackage() throws Exception {
+		ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:package-scan.xml");
+
+		Car car = applicationContext.getBean("car", Car.class);
+		assertThat(car).isNotNull();
+	}
+}

src/test/resources/package-scan.xml

@@ -0,0 +1,12 @@
+<?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:context="http://www.springframework.org/schema/context"
+       xsi:schemaLocation="http://www.springframework.org/schema/beans
+	         http://www.springframework.org/schema/beans/spring-beans.xsd
+		 http://www.springframework.org/schema/context
+		 http://www.springframework.org/schema/context/spring-context-4.0.xsd">
+
+    <context:component-scan base-package="org.springframework.test.bean"/>
+
+</beans>