手寫SpringIOC容器框架
阿新 • • 發佈：2018-11-08
1.使用xml方式注入物件
匯入依賴：
<!-- https://mvnrepository.com/artifact/dom4j/dom4j --> <dependency> <groupId>dom4j</groupId> <artifactId>dom4j</artifactId> <version>1.6.1</version> </dependency>
/** * Created by yz on 2018/6/3. */ public interface OrderService { public voidaddOrder(); }
/** * Created by yz on 2018/6/3. */ //@ExtService public class OrderServiceImpl implements OrderService { @Override public void addOrder() { System.out.println("使用Java反射機制初始化物件..."); } }
spring.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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="orderService" class="com.yz.ioc.service.Impl.OrderServiceImpl"/> </beans>
import org.dom4j.Document; importorg.dom4j.DocumentException; import org.dom4j.Element; import org.dom4j.io.SAXReader; import org.springframework.util.StringUtils; import java.io.InputStream; import java.util.List; /** * 自定義spring容器框架 xml方式實現 * Created by yz on 2018/6/3. */ public class ExtClassPathXmlApplicationContext { // xml讀取路徑地址 private String xmlPath; public ExtClassPathXmlApplicationContext(String xmlPath) { this.xmlPath = xmlPath; } public Object getBean(String beanId) throws Exception { if(StringUtils.isEmpty(beanId)){ return new Exception("bendId不能為空"); } // 1.解析xml,獲取所有bean節點資訊 List<Element> readerxml = readeXml(xmlPath); // 2.使用方法引數bend id查詢配置檔案中bean節點的id資訊是否一致。 if(readerxml == null || readerxml.isEmpty()){ return new Exception("配置檔案中，沒有配置bean資訊"); } String className = findByElementClass(readerxml, beanId); if(StringUtils.isEmpty(className)){ return new Exception("該bean物件沒有配置class地址"); } // 3.獲取class資訊地址，使用反射機制初始化 return newInstance(className); } // 重構 public String findByElementClass(List<Element> readerxml,String beanId) throws Exception { for (Element element : readerxml) { // 獲取屬性資訊 String xmlbeanId = element.attributeValue("id"); if(StringUtils.isEmpty(xmlbeanId)){ continue; } if(xmlbeanId.equals(beanId)){ String xmlClassPath = element.attributeValue("class"); return xmlClassPath; } } return null; } // 根據路徑通過反射機制獲取物件 public Object newInstance(String className) throws Exception { Class<?> classInfo = Class.forName(className); return classInfo.getDeclaredConstructor().newInstance(); } // 解析xml public List<Element> readeXml(String xmlPath) throws DocumentException { // 1.解析xml資訊 SAXReader saxReader = new SAXReader(); Document document = saxReader.read(getResourcesAsStream(xmlPath)); // 2.讀取節點下所有的子節點 Element rootElement = document.getRootElement(); // 3.獲取根節點下所有的子節點 List<Element> elements = rootElement.elements(); return elements; } // 獲取當前上下文 public InputStream getResourcesAsStream(String xmlPath){ InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(xmlPath); return inputStream; } }
import com.yz.ioc.ExtClassPathXmlApplicationContext; import com.yz.ioc.service.OrderService; /** * 測試ioc程式碼 * Created by yz on 2018/6/3. */ public class IOCTest { public static void main(String[] args) throws Exception { ExtClassPathXmlApplicationContext context = new ExtClassPathXmlApplicationContext("spring.xml"); OrderService orderService = (OrderService) context.getBean("orderService"); orderService.addOrder(); } }
2.使用註解方式注入物件 AOP IOC實現
spring.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.xsd"> <!--使用自定義註解方式，掃包範圍--> <context:component-scan base-package="com.yz.ioc"/> </beans>
import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * 自定義@Service註解 注入bean容器 */ @Target({ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) public @interface ExtService { }
import java.lang.annotation.Retention; import java.lang.annotation.Target; import static java.lang.annotation.ElementType.FIELD; import static java.lang.annotation.ElementType.METHOD; import static java.lang.annotation.ElementType.TYPE; import static java.lang.annotation.RetentionPolicy.RUNTIME; /** * 自定義@Resource註解 注入bean容器 */ @Target({TYPE, FIELD, METHOD}) @Retention(RUNTIME) public @interface ExtResource { }
/** * Created by yz on 2018/6/3. */ public interface OrderService { void addOrder(); }
/** * Created by yz on 2018/6/3. */ @ExtService public class OrderServiceImpl implements OrderService { @Override public void addOrder() { System.out.println("使用註解方式依賴注入..."); } }
/** * Created by yz on 2018/6/3. */ public interface UserService { void add(); }
import com.yz.ioc.annotation.ExtResource; import com.yz.ioc.annotation.ExtService; import com.yz.ioc.service.OrderService; import com.yz.ioc.service.UserService; /** * Created by yz on 2018/6/3. */ @ExtService public class UserServiceImpl implements UserService { @ExtResource private OrderService orderService; @Override public void add(){ orderService.addOrder(); } }
import java.io.File; import java.io.FileFilter; import java.io.IOException; import java.net.JarURLConnection; import java.net.URL; import java.net.URLDecoder; import java.util.ArrayList; import java.util.Enumeration; import java.util.List; import java.util.jar.JarEntry; import java.util.jar.JarFile; /** * 類相關的工具類 * Created by yz on 2018/6/3. */ public class ClassUtil { /** * 從包package中獲取所有的Class * @param packageName * @return */ public static List<Class<?>> getClasses(String packageName){ //第一個class類的集合 List<Class<?>> classes = new ArrayList<Class<?>>(); //是否迴圈迭代 boolean recursive = true; //獲取包的名字 並進行替換 String packageDirName = packageName.replace('.', '/'); //定義一個列舉的集合 並進行迴圈來處理這個目錄下的things Enumeration<URL> dirs; try { dirs = Thread.currentThread().getContextClassLoader().getResources(packageDirName); //迴圈迭代下去 while (dirs.hasMoreElements()){ //獲取下一個元素 URL url = dirs.nextElement(); //得到協議的名稱 String protocol = url.getProtocol(); //如果是以檔案的形式儲存在伺服器上 if ("file".equals(protocol)) { //獲取包的物理路徑 String filePath = URLDecoder.decode(url.getFile(), "UTF-8"); //以檔案的方式掃描整個包下的檔案 並新增到集合中 findAndAddClassesInPackageByFile(packageName, filePath, recursive, classes); } else if ("jar".equals(protocol)){ //如果是jar包檔案 //定義一個JarFile JarFile jar; try { //獲取jar jar = ((JarURLConnection) url.openConnection()).getJarFile(); //從此jar包 得到一個列舉類 Enumeration<JarEntry> entries = jar.entries(); //同樣的進行迴圈迭代 while (entries.hasMoreElements()) { //獲取jar裡的一個實體 可以是目錄 和一些jar包裡的其他檔案 如META-INF等檔案 JarEntry entry = entries.nextElement(); String name = entry.getName(); //如果是以/開頭的 if (name.charAt(0) == '/') { //獲取後面的字串 name = name.substring(1); } //如果前半部分和定義的包名相同 if (name.startsWith(packageDirName)) { int idx = name.lastIndexOf('/'); //如果以"/"結尾 是一個包 if (idx != -1) { //獲取包名 把"/"替換成"." packageName = name.substring(0, idx).replace('/', '.'); } //如果可以迭代下去 並且是一個包 if ((idx != -1) || recursive){ //如果是一個.class檔案 而且不是目錄 if (name.endsWith(".class") && !entry.isDirectory()) { //去掉後面的".class" 獲取真正的類名 String className = name.substring(packageName.length() + 1, name.length() - 6); try { //新增到classes classes.add(Class.forName(packageName + '.' + className)); } catch (ClassNotFoundException e) { e.printStackTrace(); } } } } } } catch (IOException e) { e.printStackTrace(); } } } } catch (IOException e) { e.printStackTrace(); } return classes; } /** * 以檔案的形式來獲取包下的所有Class * @param packageName * @param packagePath * @param recursive * @param classes */ public static void findAndAddClassesInPackageByFile(String packageName, String packagePath, final boolean recursive, List<Class<?>> classes){ //獲取此包的目錄 建立一個File File dir = new File(packagePath); //如果不存在或者 也不是目錄就直接返回 if (!dir.exists() || !dir.isDirectory()) { return; } //如果存在 就獲取包下的所有檔案 包括目錄 File[] dirfiles = dir.listFiles(new FileFilter() { //自定義過濾規則 如果可以迴圈(包含子目錄) 或則是以.class結尾的檔案(編譯好的java類檔案) public boolean accept(File file) { return (recursive && file.isDirectory()) || (file.getName().endsWith(".class")); } }); //迴圈所有檔案 for (File file : dirfiles) { //如果是目錄 則繼續掃描 if (file.isDirectory()) { findAndAddClassesInPackageByFile(packageName + "." + file.getName(), file.getAbsolutePath(), recursive, classes); } else { //如果是java類檔案 去掉後面的.class 只留下類名 String className = file.getName().substring(0, file.getName().length() - 6); try { //新增到集合中去 classes.add(Class.forName(packageName + '.' + className)); } catch (ClassNotFoundException e) { e.printStackTrace(); } } } } }
import com.yz.ioc.annotation.ExtResource; import com.yz.ioc.annotation.ExtService; import com.yz.ioc.uitl.ClassUtil; import org.dom4j.Attribute; import org.dom4j.Document; import org.dom4j.Element; import org.dom4j.io.SAXReader; import org.springframework.util.StringUtils; import java.io.InputStream; import java.lang.reflect.Field; import java.util.List; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; /** * 自定義spring容器框架 註解方式實現 * Created by yz on 2018/6/3. */ public class ExtClassPathXmlApplicationContext { // 定義springbean容器 private ConcurrentHashMap<String,Object> beans; // 掃包的範圍 private String packageName; public ExtClassPathXmlApplicationContext(String xmlPath) throws Exception { // 初始化引數 beans = new ConcurrentHashMap<>(); this.packageName = getPackageName(xmlPath); initBeans(); initEntryField(); } // 初始化屬性 private void initEntryField() throws Exception { // 1.遍歷所有bena容器物件 for (Map.Entry<String, Object> entry : beans.entrySet()) { // 2.判斷屬性上面是否有加註解 Object object = entry.getValue(); inversionOfControl(object); } } public Object getBean(String beanId) throws Exception { System.out.println(beanId); if(StringUtils.isEmpty(beanId)){ throw new Exception("beanId引數不能為空"); } // 從spring容器獲取bean Object object = beans.get(beanId); return object; } // 根據路徑通過反射機制獲取物件 public Object newInstance(Class<?> classInfo) throws Exception { return classInfo.getDeclaredConstructor().newInstance(); } // 初始化物件 public void initBeans() throws Exception { // 1.使用Java的反射機制掃包，獲取當前包下所有的類 List<Class<?>> classes = ClassUtil.getClasses(packageName); // 2.判斷類上是否存在注入bean的註解 ConcurrentHashMap<String, Object> classIsAnnotation = findClassIsAnnotation(classes); if(classIsAnnotation == null || classIsAnnotation.isEmpty()){ throw new Exception("該包下沒有任何類加上註解"); } } // 判斷類上是否存在注入bean的註解 public ConcurrentHashMap<String,Object> findClassIsAnnotation(List<Class<?>> classes) throws Exception { for (Class<?> classInfo : classes) { // 判斷類上是否有註解 ExtService annotation = classInfo.getAnnotation(ExtService.class); if(annotation !=null){ // 獲取當前類名，beanid 預設類名小寫 String className = classInfo.getSimpleName(); String beanId = toLowerCaseFirstOne(className); // 通過反射機制建立物件 Object newInstance = newInstance(classInfo); beans.put(beanId,newInstance); continue; } } return beans; } //首字母轉小寫 public static String toLowerCaseFirstOne(String s){ if(Character.isLowerCase(s.charAt(0))) return s; else return (new StringBuilder()) .append(Character.toLowerCase(s.charAt(0))) .append(s.substring(1)).toString(); } // 讀取xml中配置的包路徑 public String getPackageName(String xmlPath) throws Exception { SAXReader saxReader = new SAXReader(); // 讀取xml檔案 Document document = saxReader.read(getResourcesAsStream(xmlPath)); // 讀取節點 Element rootElement = document.getRootElement(); // 獲取根節點下所有的子節點 List<Element> elements = rootElement.elements(); for (Element element : elements) { if(element.getName().equals("component-scan")){ // 獲取掃包路徑 Attribute attribute = element.attribute("base-package"); return attribute.getText(); } } return null; } public InputStream getResourcesAsStream(String xmlPath){ InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(xmlPath); return inputStream; } // 依賴注入 public void inversionOfControl(Object object) throws Exception { // 依賴注入實現原理 // 1.使用反射機制，獲取當前類的所有屬性 Class<?> classInfo = object.getClass(); Field[] fileds = classInfo.getDeclaredFields(); // 2.判斷當前類屬性是否存在註解 for (Field filed : fileds) { // 3.預設使用屬性名稱，查詢bean容器物件 ExtResource extResource = filed.getAnnotation(ExtResource.class); if(extResource !=null){ // 獲取屬性名稱 String beanId = filed.getName(); Object bean = getBean(beanId+"Impl"); if(bean != null){ // 允許訪問私有屬性 filed.setAccessible(true); // 屬性賦值 filed.set(object,bean); } } } } }
/** * Created by yz on 2018/6/3. */ public class IOCTest { public static void main(String[] args) throws Exception { ExtClassPathXmlApplicationContext context = new ExtClassPathXmlApplicationContext("spring.xml"); // OrderService orderService = (OrderService) context.getBean("orderServiceImpl"); // orderService.addOrder(); UserService userService = (UserService) context.getBean("userServiceImpl"); userService.add(); } }
