手写Spring框架源码

package org.cheney.summer; import org.cheney.summer.annotation.Autowired; import org.cheney.summer.annotation.Component; import org.cheney.summer.annotation.ComponentScan; import org.cheney.summer.annotation.Scope; import java.beans.Introspector; import java.io.File; import java.lang.annotation.Annotation; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.net.URL; import java.util.ArrayList; import java.util.concurrent.ConcurrentHashMap; /** * Hello world! */ public class SummerApplicationContext { private Class configClass; private ConcurrentHashMap beanDefinitionMap = new ConcurrentHashMap<>(); private ConcurrentHashMap singletonBeanMap = new ConcurrentHashMap<>(); private ArrayList beanPostProcessorList = new ArrayList<>(); public SummerApplicationContext(Class configClass) { this.configClass = configClass; if (configClass.isAnnotationPresent(ComponentScan.class)) { ComponentScan scanAnnotation = (ComponentScan) configClass.getAnnotation(ComponentScan.class); String pathValue = scanAnnotation.value(); // org.cheney.service String[] paths = pathValue.split(","); for (String path : paths) { path = path.replace(".", "/"); ClassLoader classLoader = SummerApplicationContext.class.getClassLoader(); URL resource = classLoader.getResource(path); File file = new File(resource.getFile()); if (file.isDirectory()) { File[] files = file.listFiles(); for (File f : files) { String absolutePath = f.getAbsolutePath(); if (absolutePath.endsWith(".class")) { // 判断目录下的.class文件是否有 @Component注解 String className = absolutePath.substring(absolutePath.indexOf("org"), absolutePath.indexOf(".class")); className = className.replace("\\", "."); // System.out.println(className); try { Class clazz = classLoader.loadClass(className); if (clazz.isAnnotationPresent(Component.class)) { // 扫描到了 @Component 注解，生成一个 BeanDefinition 对象 BeanDefinition beanDefinition = new BeanDefinition(); beanDefinition.setType(clazz); if (clazz.isAnnotationPresent(Scope.class)) { String value = clazz.getAnnotation(Scope.class).value(); beanDefinition.setScope(value); } else { beanDefinition.setScope("singleton"); } String beanName = clazz.getAnnotation(Component.class).value(); if ("".equals(beanName)) { // beanName = getBeanName(clazz); beanName = Introspector.decapitalize(clazz.getSimpleName()); } beanDefinitionMap.put(beanName, beanDefinition); // 前置 后置 处理器 if (BeanPostProcessor.class.isAssignableFrom(clazz)) { BeanPostProcessor instance = (BeanPostProcessor) clazz.newInstance(); beanPostProcessorList.add(instance); } } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (InstantiationException e) { throw new RuntimeException(e); } catch (IllegalAccessException e) { throw new RuntimeException(e); } } } } } } // 将beanDefinition中的Singleton进行实例化 for (String beanName : beanDefinitionMap.keySet()) { BeanDefinition beanDefinition = beanDefinitionMap.get(beanName); if ("singleton".equals(beanDefinition.getScope())) { Object bean = createBean(beanName, beanDefinition); singletonBeanMap.put(beanName, bean); } } } private Object createBean(String beanName, BeanDefinition beanDefinition) { Class clazz = beanDefinition.getType(); try { Object bean = clazz.getConstructor().newInstance(); // 实现依赖注入 Field[] fields = clazz.getDeclaredFields(); for (Field f : fields) { if (f.isAnnotationPresent(Autowired.class)) { f.setAccessible(true); f.set(bean, getBean(f.getName())); } } // Aware 回调 if (bean instanceof BeanNameAware) { ((BeanNameAware) bean).setBeanName(beanName); } // BeanPostProcessor 初始化前，前置处理器 for (BeanPostProcessor processor : beanPostProcessorList) { processor.postProcessorBeforeInitialization(beanName,bean); } // 初始化 if (bean instanceof InitializingBean) { ((InitializingBean) bean).afterPropertiesSet(); } // BeanPostProcessor 初始化后，后置处理器 for (BeanPostProcessor processor : beanPostProcessorList) { processor.postProcessorAfterInitialization(beanName,bean); } return bean; } catch (InstantiationException e) { throw new RuntimeException(e); } catch (IllegalAccessException e) { throw new RuntimeException(e); } catch (InvocationTargetException e) { throw new RuntimeException(e); } catch (NoSuchMethodException e) { throw new RuntimeException(e); } } public Object getBean(String beanName) { BeanDefinition beanDefinition = beanDefinitionMap.get(beanName); if (null == beanDefinition) { throw new NullPointerException("Summer容器中不存在叫做" + beanName + "的Bean"); } if (beanDefinition.getScope().equals("singleton")) { Object bean = singletonBeanMap.get(beanName); if (null == bean) { bean = createBean(beanName, beanDefinition); singletonBeanMap.put(beanName, bean); } return bean; } else { return createBean(beanName, beanDefinition); } } }