利用Spring的@Import扩展点与spring进行无缝整合

spring有那些扩展呢?
spring的扩展非常多,比较常用的就是
BeanFactoryPostProcessor 我们可以插手spring bean工厂的初始化
BeanPostProcessor 我们可以插手spring bean实例化前后(比如SPRING AOP)
@Import
ImportAware。

BeanFactoryPostProcessor

spring的扩展点之一BeanFactoryPostProcessor,这个学名叫spring的Bean工厂后置处理器,
它可以插手spring bean工厂的实例化,我们可以启动spring的时候自己手动注册一个bean工厂后置处理器,它能做的事情太多,研究过spring源码的同学都知道,spring容器启动时候,会先暴露一个工厂出来,这个工厂就是DefaultListableBeanFactory,这里面放置了我们的BeanDeinition,我们都知道spring 单例bean容器放了很多单例的bean,而这些bean最后都是来自于DefaultListableBeanFactory中的bd容器;
BeanFactoryPostProcessor是spring提供给我们来扩展spring的,当然了它自己也在用,spring有自己内部的bean工厂后置处理器,处理的时候讲我们的和spring自己的一起处理。我们只需要把我们新建的类实现了BeanFactoryPostProcessor,并且加入@Component或者交给@Import就可以了。实现这个接口必须实现它的一个方法,它的这个方法就可以得到我们的beanDefinittionMap,也就是bdmap,这里面放置了我们系统所有的注册到spring容器里面的bd,最后spring循环这个bd,将其实例化成对象放入Bean容器。

今天我们的主题是使用sprinng的扩展点之一的@Import来实现公司的平台与spring整合,类似于Mybatis与spring整合一样

@Import

这个要说就要说很久,如果没有研究过spring底层源码的,可以去研究下,功能非常强大这边我大概介绍一下:
@import支持3中类型:
普通类(spring管理的类):就是讲一个普通的类通过@import导入,而不适用@Component,但是这样做毫无意义。
实现了ImportSelector:实现这个接口要求实现它的一个方法返回一个类名列表
Registrar:真正牛逼的注册类,实现了它,我们可以手动往里面添加自己的BeanDefiniton,自己实现扫描机制,自己实现很多很多自己的逻辑(mybatis整合spring就用的它)

实现

我的工程命名是:xxx-spring-platform-1.0.REALSE
xxx是公司的简称
工程结构:
image
其中context是核心,core是一些常用的核心类,aop写了一半,还没完成

POM文件

 <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>5.2.7.RELEASE</version>
      </dependency>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.2.7.RELEASE</version>
      </dependency>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>5.2.7.RELEASE</version>
      </dependency>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>5.2.7.RELEASE</version>
      </dependency>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>5.2.7.RELEASE</version>
      </dependency>

就是用了srping的几个基础包

定义数据层Resource(dao)层的扫描注解

@Documented
@Retention(RUNTIME)
@Target(TYPE)
@Import(ArteryResourceImportBeanDefinitionRegistrar.class)
//这个是用了spring的@Import
//其中用了其扩展点之一的@Import中的Registrar,ArteryResourceImportBeanDefinitionRegistrar才是我们的核心所在
public @interface ArteryResourceScan {

    String[] value() default {};

    /**
     * 基础包模式
     */
    String[] basePackages() default {};

    /**
     * 通配符的模式
     */
    String[] typeAliases() default {};

    /**
     * Artery Resource工厂Bean
     *
     * @return
     */
    Class<? extends ArteryResourceFactoryBean> factoryBean() default ArteryResourceFactoryBean.class;

    /**
     * This property specifies the annotation that the scanner will  search for.
     * <p>
     * The scanner will register all interfaces in the base package that also have
     * the specified annotation
     * </p>
     */
    Class<? extends Annotation> annotationClass() default Annotation.class;

    /**
     * This property specifies the parent that the scanner will search for.
     * <p>
     * The scanner will register all interfaces in the base package that also have
     * the specified interface class as a parent.
     * </p>
     */
    Class<?> markerInterface() default Class.class;

    /**
     * The property specifies the beanName gererator will extends parent
     */

    Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;

    /**
     * is lazy load,default false
     */
    boolean lazy() default false;

    /**
     * scope default singleton
     */
    String scope() default AbstractBeanDefinition.SCOPE_SINGLETON;

}

定义我的数据层Resource使用的注解

image

ArteryResourceImportBeanDefinitionRegistrar实现

我们的注册类实现了spring的即可ImportBeanDefinitionRegistrar,而ImportBeanDefinitionRegistrar提供了一个方法registerBeanDefinitions可以得到我们的ArteryResourceScan 注解,从而定义自己的扫描规则,使用spring的的扫描逻辑帮助我们完成扫描,然后注册到bdmap里面,因我们的Resource层是接口,而spring实例化是不能实例化接口的,所以当spring帮我们扫描成bd的时候,我们这个时候要这个扫描的列表取出来,替换我们的接口类,怎么替换呢?
因为接口需要被代理出去,而代理类帮我们完成我们想要做的事情,比如数据查询,所以我们还需要定义一个工厂bean即FactoryBean,它来帮我们产生对象,FactoryBean也是一个Bean,但是他比较特殊,它可以产生对象,我们先看Registrar的实现:

public class ArteryResourceImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {

    private final String DEFAULT_RESOURACE_PATTERN = "**/*.class";

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {

        ClassPathArteryResourceScanner scanner = new ClassPathArteryResourceScanner(registry);
        /**
         * 拿到注解信息
         */
        AnnotationAttributes annoAttrs = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(ArteryResourceScan.class.getName()));

        Class<? extends ArteryResourceFactoryBean> factoryBean = annoAttrs.getClass("factoryBean");
        if (!ArteryResourceFactoryBean.class.equals(factoryBean)) {
            scanner.setArteryResourceFactoryBean(BeanUtils.instantiateClass(factoryBean));
        }
        Class<? extends Annotation> annotionClass = annoAttrs.getClass("annotationClass");
        if (!Annotation.class.equals(annotionClass)) {
            scanner.setAnnotationClass(annotionClass);
        }
        Class<?> markerInteface = annoAttrs.getClass("markerInterface");
        if (!Class.class.equals(markerInteface)) {
            scanner.setMarkerInterface(markerInteface);
        }

        Class<? extends BeanNameGenerator> nameGenerator = annoAttrs.getClass("nameGenerator");
        if (!BeanNameGenerator.class.equals(nameGenerator)) {
            scanner.setBeanNameGenerator(BeanUtils.instantiateClass(nameGenerator));
        }
        scanner.setLazy(annoAttrs.getBoolean("lazy"));
        scanner.setResourceScope(annoAttrs.getString("scope"));
        //base package handler
        List<String> basePackages = new ArrayList<>(20);
        Arrays.asList(annoAttrs.getStringArray("basePackages")).forEach(item -> {
            if (StringUtils.hasText(item)) {
                basePackages.add(item);
            }
        });
        Arrays.asList(annoAttrs.getStringArray("value")).forEach(item -> {
            if (StringUtils.hasText(item)) {
                basePackages.add(item);
            }
        });


        /**
         * 处理通配符的扫描问题
         */
        String[] typeAlis = annoAttrs.getStringArray("typeAliases");
        if (typeAlis != null && typeAlis.length > 0) {
            ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
            MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(resolver);
            //typeAliaes
            for (String typeAliases : Arrays.asList(annoAttrs.getStringArray("typeAliases"))) {
                getResource(resolver, metadataReaderFactory, typeAliases, basePackages);
            }
        }
        scanner.registerFilters();
        scanner.doScan(StringUtils.toStringArray(basePackages));
    }

    private void getResource(ResourcePatternResolver resolver, MetadataReaderFactory metadataReaderFactory, String classPath, List<String> basePackages) {
        classPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX + ClassUtils.convertClassNameToResourcePath(classPath) + "/" + DEFAULT_RESOURACE_PATTERN;
        try {
            Resource[] resources = resolver.getResources(classPath);
            if (resources != null && resources.length > 0) {
                MetadataReader metadataReader = null;
                for (Resource resource : resources) {
                    if (resource.isReadable()) {
                        metadataReader = metadataReaderFactory.getMetadataReader(resource);
                        basePackages.add(Class.forName(metadataReader.getClassMetadata().getClassName()).getPackage().getName());
                    }
                }
            }
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}

以上代码的doScan方法是核心,是调用了我们自定义的扫描类

自定义扫描类ClassPathArteryResourceScanner

public class ClassPathArteryResourceScanner extends ClassPathBeanDefinitionScanner {
    private final Logger logger = LoggerFactory.getLogger(ClassPathArteryResourceScanner.class);
    /**
     * factory baen instance
     */
    private ArteryResourceFactoryBean<?> arteryResourceFactoryBean = new ArteryResourceFactoryBean<Object>();
    /**
     * scanner class
     */
    private Class<? extends Annotation> annotationClass;
    /**
     * scanner class
     */
    private Class<?> markerInterface;
    /**
     * is lazy load ,default false
     */
    private boolean isLazy = false;
    /**
     * scope is cantains singleton and prototype,default singlton
     */
    private String resourceScope = AbstractBeanDefinition.SCOPE_SINGLETON;


    /**
     * 调用父类的构造,构造出扫描对象
     *
     * @param registry
     */
    public ClassPathArteryResourceScanner(BeanDefinitionRegistry registry) {
        super(registry, false);
    }

    public void registerFilters() {
        //是否允许所有的所有的接口(预留)
        boolean acceptAllIntefaces = true;

        if (this.annotationClass != null) {
            addIncludeFilter(new AnnotationTypeFilter(this.annotationClass));
            acceptAllIntefaces = false;
        }
        if (this.markerInterface != null) {
            addIncludeFilter(new AssignableTypeFilter(this.markerInterface));
            acceptAllIntefaces = false;
        }
        if (acceptAllIntefaces) {
            addIncludeFilter(new TypeFilter() {
                @Override
                public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException {
                    return true;
                }
            });
        }

    }

    @Override
    public Set<BeanDefinitionHolder> doScan(String... basePackages) {

        Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
        if (!beanDefinitions.isEmpty()) {
            //SPRING 扫描到每个加了@Component或者@Service 成BD
            processBeanDefinitions(beanDefinitions);
        }
        return beanDefinitions;
    }

    private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) {
        beanDefinitions.forEach(this::processBeanDefinition);
    }

    private void processBeanDefinition(BeanDefinitionHolder holder) {
        GenericBeanDefinition definition = (GenericBeanDefinition) holder.getBeanDefinition();
        if (logger.isDebugEnabled()) {
            logger.debug("Creating ArteryResourceBean with name {} and {} mapperInterfaces", holder.getBeanName(), definition.getBeanClassName());
        }
        definition.getConstructorArgumentValues().addGenericArgumentValue(definition.getBeanClassName());
        definition.setBeanClass(this.arteryResourceFactoryBean.getClass());
        definition.setLazyInit(isLazy);//延迟加载
        definition.setScope(resourceScope);
        definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
    }


    @Override
    protected boolean checkCandidate(String beanName, BeanDefinition beanDefinition) throws IllegalStateException {
        // check is sucess
        boolean isSucc = true;
        if (super.checkCandidate(beanName, beanDefinition)) {
            isSucc = true;
        } else {
            isSucc = false;
        }
        return isSucc;
    }

    @Override
    protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) {
        boolean isComponent = false;
        String beanClassName = beanDefinition.getMetadata().getClassName();
        isComponent = beanClassName.endsWith("Resource");
        try {

            isComponent = isComponent ? Class.forName(beanDefinition.getMetadata().getClassName()).isAnnotationPresent(ArteryDao.class) : false;
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        if (isComponent) {
            isComponent = beanDefinition.getMetadata().isInterface() && beanDefinition.getMetadata().isIndependent();
        }
        return isComponent;
    }

    public void setArteryResourceFactoryBean(ArteryResourceFactoryBean<?> arteryResourceFactoryBean) {
        this.arteryResourceFactoryBean = arteryResourceFactoryBean;
    }

    public void setAnnotationClass(Class<? extends Annotation> annotationClass) {
        this.annotationClass = annotationClass;
    }

    public void setLazy(boolean lazy) {
        isLazy = lazy;
    }

    public void setResourceScope(String resourceScope) {
        this.resourceScope = resourceScope;
    }

    public void setMarkerInterface(Class<?> markerInterface) {
        this.markerInterface = markerInterface;
    }
}


processBeanDefinition这个方法里面就拿到spring给我们扫描返回的bd,我们循环这个bd
然后替换我们的Resource接口,这里用的是一个FactoryBean
而这个工厂Bean里面的getObject是返回了一个代理对象,具体看下面代码:

代理注册工厂ResourceRegistry


它的作用主要是来管理我们的注册工厂

Resouce的代理工厂


它来管理我们的Resouce工厂,从这个Resource工厂中产生代理类,也就是我们的代理类都在代理工厂中产生,然后我们调用的时候是通过它来产生的一个proxy

真正的代理类

public class ResourceProxy<T> implements InvocationHandler, Serializable {
    private static final long serialVersionUID = 1L;
    private final Logger logger = LoggerFactory.getLogger(ResourceProxy.class);

    private final Class<T> resourceInterface;
    private final Map<Method, ResourceMethod> cacheMethod;


    public ResourceProxy(Class<T> resourceInterface, Map<Method, ResourceMethod> cacheMethod) {
        this.resourceInterface = resourceInterface;
        this.cacheMethod = cacheMethod;
    }


    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Object result = null;
        /**
         * handler tostring method
         */
        if (Object.class.equals(method.getDeclaringClass())) {
            result = method.invoke(this, args);
        } else if (isDefaultMethod(method)) {
            result = invokeDefaultMethod(proxy, method, args);
        } else {
            /**
             * user invoke handler
             */
            if (logger.isDebugEnabled()) {
                logger.debug("ResourceProxy.invoke begin ....");
                logger.debug("================================================");
                logger.debug("invoke interface name={}", proxy.getClass().getInterfaces()[0].getName());
                logger.debug("invoke method name={}", method.getName());
                logger.debug("invoke method args={}", args);
            }
            ResourceMethod resourceMethod = getCacheMethod(method);
            result = resourceMethod.execute(args);
            if (logger.isDebugEnabled()) {
                logger.debug("ResourceProxy.invoke end ....");
                logger.debug("================================================");
                logger.debug("invoke method result={}", result);
            }
        }
        return result;
    }

    public ResourceMethod getCacheMethod(Method method) {
        ResourceMethod resourceMethod = cacheMethod.get(method);
        if (resourceMethod == null) {
            resourceMethod = new ResourceMethod(method, resourceInterface);
            cacheMethod.put(method, resourceMethod);
        }
        return resourceMethod;
    }


    /**
     * invoke default method
     *
     * @param proxy  proxy object
     * @param method proxy invoke method
     * @param args   method args
     * @return
     * @throws Throwable
     */
    private Object invokeDefaultMethod(Object proxy, Method method, Object[] args) throws Throwable {
        final Constructor<MethodHandles.Lookup> constructor = MethodHandles.Lookup.class.getDeclaredConstructor(Class.class, int.class);
        if (!constructor.isAccessible()) {
            constructor.setAccessible(true);
        }
        final Class<?> declaringClass = method.getDeclaringClass();
        return constructor.newInstance(declaringClass, MethodHandles.Lookup.PRIVATE)
                .unreflectSpecial(method, declaringClass).bindTo(proxy).invokeWithArguments(args);
    }

    /**
     * check is default method
     *
     * @param method
     * @return
     */
    private boolean isDefaultMethod(Method method) {
        return ((method.getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) == Modifier.PUBLIC) && method.getDeclaringClass().isInterface();
    }
}


方法调用类

public class ResourceMethod<T> extends AbstractAnnotaionHandlerResource<T> {

    private final Method method;

    private final Class<?> resourceInterface;


    public ResourceMethod(Method method, Class<?> resourceInterface) {
        this.method = method;
        this.resourceInterface = resourceInterface;
    }

    public Object execute(Object[] args) throws Exception {
        Object result = null;
        initTemplate();
        if (method.isAnnotationPresent(PubHandler.class)) {
            result = pubHandler(args);
        } else {
            result = invokeExtMethod(args);
        }
        return result;
    }

    private void initTemplate(){
        if(queryTemplate == null){
            queryTemplate = SpringContainerApplicationContext.getInstance().getBean("queryTemplate");
        }

        if(updateTemplate == null){
            updateTemplate =SpringContainerApplicationContext.getInstance().getBean("updateTemplate");

        }
    }

    private Object invokeExtMethod(Object[] args) throws Exception {
        Object result = null;
        Annotation[] annotations = method.getAnnotations();
        if (annotations != null && annotations.length > 0) {
            String annotationName = annotations[0].annotationType().getSimpleName();
            SqlCommandType type = SqlCommandType.valueOf(annotationName);
            switch (type) {
                case SELECT:
                    result = executeQuery(method.getAnnotation(SELECT.class), args);
                    break;
                case INSERT:
                    result = executeInsert(method.getAnnotation(INSERT.class), args);
                    break;
                case DELETE:
                    result = executeDelete(method.getAnnotation(DELETE.class), args);
                    break;
                case UPDATE:
                    result = executeUpdate(method.getAnnotation(UPDATE.class), args);
                    break;
            }
        }
        return result;
    }


    private Object pubHandler(Object[] args) {
        Object result = null;
        PubHandler ph = method.getAnnotation(PubHandler.class);
        switch (ph.handlerType()) {
            case P_Q_PAGING:
                result = P_Q_PAGING(args);
                break;
            case L_Q_PAGING:
                result = L_Q_PAGING(args);
                break;
            case I_PERSISTENCE_IN:
                result = I_PERSISTENCE_IN(args);
                break;
            case I_PERSISTENCE_UP:
                result = I_PERSISTENCE_UP(args);
                break;
            case I_PERSISTENCE_UP_OVERRIDE:
                result = I_PERSISTENCE_UP_OVERRIDE(args);
                break;
            case I_PSERSISTENCE_DE:
                result = I_PSERSISTENCE_DE(args);
                break;
            case I_PSERSISTENCE_DE_OVERRIDE:
                result = I_PSERSISTENCE_DE_OVERRIDE(args);
                break;
            case E_Q_GET:
                result = E_Q_GET(args);
                break;
            case L_Q_ENTITY:
                result = L_Q_ENTITY(args);
                break;
            case L_Q_ENTITY_OVERRIDE:
                result = L_Q_ENTITY_OVERRIDE(args);
                break;
            case I_BATCH_PERSISTENCE:
                result = I_BATCH_PERSISTENCE(args);
                break;
            case I_COUNT:
                result = I_COUNT(args);
                break;
        }
        return result;
    }
    @Override
    public Method getMethod() {
        return method;
    }

    @Override
    public Class<?> targetInterface() {
        return resourceInterface;
    }


}


从第七步调用直接到了这里,其中1和2是不一样的,哪里不一样呢?因为pubHandler是我们在基类里面封装的curd操作,如果是调用基类,那么会直接将请求代理给我的基类去做,如果是通过注解sql的那么就执行invokeExtMethod



最后我们编写一个工厂来获取我们的Bean

AbstractBeanDefinitionFactory

public abstract class AbstractBeanDefinitionFactory extends AnnotationConfigDefinitionApplicationContext
		implements BeanDefinitionFactory {

	@SuppressWarnings("unchecked")
	@Override
	public <K> K getBean(String beanName) {
		check();
		DefinitionBeanFactory<K> beanfactory = () -> {
			Object beanInstance = super.applicationContxt.getBean(beanName);
			if (beanInstance != null) {
				return (K) beanInstance;
			} else {
				throw new RuntimeException(" get spring ioc instance is null ");
			}
		};
		return beanfactory.getBeanObject();
	}

	@Override
	public <K> K getBean(Class<K> kclzz) {
		check();
		DefinitionBeanFactory<K> beanfactory = () -> super.applicationContxt.getBean(kclzz);
		return beanfactory.getBeanObject();
	}
	
	private void check() {
		if(!super.runStatus) {
			throw new RuntimeException("spring 容器未运行");
		}
	}

	@Override
	public <K> K getBean(String beanName, Class<K> kClass) {
		check();
		DefinitionBeanFactory<K> beanFactory = () -> super.applicationContxt.getBean(beanName,kClass);
		return null;
	}
}

我们编写测试,来启动我们的spring容器




以上我只是提供了一个spring扩展的思路,上面截图和代码都不全,因为涉及到公司机密性,我没有办法暴露太多东西在上面,所以有兴趣可以一起交流交流;整合spring的这个框架是我自己编写,没有任何人参与进来,所以我希望如果有这方面兴趣的朋友可以一起交流交流,最后附上我的qq:631491652

类图

我的启动类的之间关系(全部是自己的类,不是spring的类):


代理工厂调用的调用的方法处理继承关系:
image
最后预祝我的两个小公主一直开心快乐,身体永远健康,爸爸永远爱你们。(女儿很可爱 :smiley:


原文:https://blog.csdn.net/scjava/article/details/107861181

1 Like

羡慕了,人生赢家 :blush: