看了spring ioc部分的代码，个人感觉在spring完成bean创建的过程后，做一个类实现ApplicationContextAware接口，然后克隆多个需要的BeanDefinition，附不同的业务参数属性值的方式比较讨巧。新增加的BeanDefinition会在getBean的过程中，由spring创建。
下面分两部分介绍：
1、动态创建bean的代码实现
2、spring的ioc源码解读，这部分放到另外一篇博客 http://mazhen2010.iteye.com/blog/2283773
<spring.version>4.0.6.RELEASE</spring.version>
【动态创建bean的代码实现】
1、创建一个实现ApplicationContextAware接口的类，然后获取DefaultListableBeanFactory
private void setSpringFactory(ApplicationContext applicationContext) {
if (applicationContext instanceof AbstractRefreshableApplicationContext) {
// suit both XmlWebApplicationContext and ClassPathXmlApplicationContext
AbstractRefreshableApplicationContext springContext = (AbstractRefreshableApplicationContext) applicationContext;
if (!(springContext.getBeanFactory() instanceof DefaultListableBeanFactory)) {
LOGGER.error("No suitable bean factory! The current factory class is {}",
springContext.getBeanFactory().getClass());
}
springFactory = (DefaultListableBeanFactory) springContext.getBeanFactory();
} else if (applicationContext instanceof GenericApplicationContext) {
// suit GenericApplicationContext
GenericApplicationContext springContext = (GenericApplicationContext) applicationContext;
springFactory = springContext.getDefaultListableBeanFactory();
} else {
LOGGER.error("No suitable application context! The current context class is {}",
applicationContext.getClass());
}
}
2、定义注解，以找到需要克隆的BeaDefinition和需要赋值的属性
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface TemplateService {
//服务名称
String serviceName();
//服务实现名称
String value() default "";
}
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface TemplateBizParam {
}
@TemplateService(serviceName = "demoService", value = "demoServiceImpl")
public class DemoServiceImpl extends AbstractServiceImpl implements DemoService {
@TemplateBizParam
private String noVisitDays;
@Override
public void doDemo(Long poiId) {
StringBuilder builder = new StringBuilder("doDemo").append("//").append("poiId:").append(poiId);
builder.append("//").append(noVisitDays).append("//").append(getExtendFields()).append("//");
builder.append("abc:").append(getExtendField("abc"));
System.out.println(builder.toString());
}
@Override
public void doDemos(List<Long> poiIds) {
System.out.println("poiIds" + poiIds + "; noVisitDays:" + noVisitDays);
}
}
3、从垂类模板中获取需要动态创建的bean信息，然后注册BeanDefinition
private void registerBeanDefinition(String templateId, ServiceEntity serviceEntity) {
try {
if (springFactory.containsBeanDefinition(serviceEntity.getImplName())) {
//step1: 注入多个实例
String beanKey = generateTemplateBeanName(templateId, serviceEntity.getServiceName());
BeanDefinition beanDefinition = springFactory.getBeanDefinition(serviceEntity.getImplName());
String className = beanDefinition.getBeanClassName();
Class c = null;
try {
c = Class.forName(className);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(className);
beanDefinitionBuilder.getBeanDefinition().setAttribute("id", beanKey);
springFactory.registerBeanDefinition(
beanKey, beanDefinitionBuilder.getBeanDefinition());
LOGGER.info("Register bean definition successfully. beanName:{}, implName:{}",
generateTemplateBeanName(templateId, serviceEntity.getServiceName()), serviceEntity.getImplName());
//step2: 为实例自动化注入属性
Object bean = springFactory.getBean(beanKey, c);
injectParamVaules(bean, c, serviceEntity);
}
} catch (NoSuchBeanDefinitionException ex) {
LOGGER.info("No bean definition in spring factory. implName:{}", serviceEntity.getImplName());
} catch (BeanDefinitionStoreException ex) {
LOGGER.info("Register bean definition wrong. beanName:{}, implName:{}",
generateTemplateBeanName(templateId, serviceEntity.getServiceName()), serviceEntity.getImplName());
}
}
private <T> void injectParamVaules(Object bean, Class<T> requiredType, ServiceEntity serviceEntity) {
if (requiredType.isAnnotationPresent(TemplateService.class)) {
Field[] fields = requiredType.getDeclaredFields(); //获取类的所有属性
for (Field field : fields) {
// 注入业务参数
if (field.isAnnotationPresent(TemplateBizParam.class)) {
field.setAccessible(true);
try {
if ((serviceEntity.getBizParamMap() != null) && (serviceEntity.getBizParamMap().containsKey(field.getName()))) {
field.set(bean, serviceEntity.getBizParamMap().get(field.getName()));
LOGGER.info("inject biz param value successfully, paramName = {}, value = {}", field.getName(), serviceEntity.getBizParamMap().get(field.getName()));
}
} catch (IllegalAccessException e) {
LOGGER.error("inject biz param failed. {}", e.getMessage());
e.printStackTrace();
}
}
}
Class<AbstractService> superClass = getSuperClass(requiredType);
if(superClass != null) {
Field[] superFields = superClass.getDeclaredFields(); //获取类的所有属性
for (Field field : superFields) {
// 注入扩展字段
if (field.isAnnotationPresent(TemplateExtendFields.class)) {
field.setAccessible(true);
try {
if(serviceEntity.getExtendFields() != null){
field.set(bean, serviceEntity.getExtendFields());
LOGGER.info("inject extend fields successfully, extendFields = {}", serviceEntity.getExtendFields());
}
} catch (IllegalAccessException e) {
LOGGER.error("inject extend fields failed. {}", e.getMessage());
e.printStackTrace();
}
}
}
}
}
}
4、定义一个Context继承AbstractServiceContext，实现运行时根据策略，选取所需的业务实例进行处理
@Service("demoService")
public class DemoServiceContext extends AbstractServiceContext implements DemoService {
@Override
public void doDemo(Long poiId) {
getServiceImpl(poiId, DemoService.class).doDemo(poiId);
}
}
/**
* 服务上下文抽象类，负责具体服务实现类的策略选择和扩展字段传递.
* User: mazhen01
* Date: 2016/3/3
* Time: 10:14
*/
public abstract class AbstractServiceContext {
@Resource
private TemplateBeanFactory templateBeanFactory;
@Autowired
public TemplateFunction templateFunction;
// 当前线程使用的beanName
private ThreadLocal<String> currentTemplateBeanName = new ThreadLocal<String>();
private static final Logger LOGGER = LoggerFactory.getLogger(AbstractServiceContext.class);
/**
* 根据POI所属行业，获取服务实例
*
* @param poiId poiId
* @param clazz 服务接口
* @param <T> 实例类型
* @return
* @throws AnnotationException
* @throws BeansException
*/
protected <T> T getServiceImpl(Long poiId, Class<T> clazz) throws AnnotationException, BeansException {
String serviceName = getServiceName();
String templateId = templateFunction.getTemplateId(poiId, serviceName);
if (templateId == null) {
LOGGER.error("templateId is null. No templateId id configured for poiId = {}.", poiId);
throw new TemplateException("templateId is null, can not find templateId.");
}
currentTemplateBeanName.set(TemplateBeanFactory.generateTemplateBeanName(templateId, serviceName));
return templateBeanFactory.getBean(TemplateBeanFactory.generateTemplateBeanName(templateId, serviceName), clazz);
}
protected <T> T getServiceImpl(List<Long> poiIds, Class<T> clazz) throws AnnotationException, BeansException {
if (CollectionUtils.isEmpty(poiIds)) {
LOGGER.error("poiIds List is null");
throw new TemplateException("poiIds is null.");
}
Long poiId = poiIds.get(0);
return getServiceImpl(poiId, clazz);
}
/**
* 根据beanName，获取服务实例
*
* @param templateBeanName beanName
* @param clazz 服务接口
* @param <T> 实例类型
* @return
* @throws AnnotationException
* @throws BeansException
*/
protected <T> T getServiceImpl(String templateBeanName, Class<T> clazz) throws AnnotationException, BeansException {
return templateBeanFactory.getBean(templateBeanName, clazz);
}
/**
* 根据POI所属行业，获取服务实例的扩展字段列表
*
* @param poiId
* @return
*/
public List<String> getExtendFields(Long poiId) {
AbstractServiceImpl abstractService = getServiceImpl(poiId, AbstractServiceImpl.class);
if (abstractService == null || CollectionUtils.isEmpty(abstractService.getExtendFields())) {
Lists.newArrayList();
}
return abstractService.getExtendFields();
}
/**
* 根据POI所属行业，设置服务实例所需要的扩展字段的具体值
*
* @param poiId poiId
* @param request 用户请求
*/
public void setExtendField(Long poiId, HttpServletRequest request) {
if (request == null) {
return;
}
AbstractServiceImpl abstractService = getServiceImpl(poiId, AbstractServiceImpl.class);
if (abstractService == null || CollectionUtils.isEmpty(abstractService.getExtendFields())) {
return;
}
for (String field : abstractService.getExtendFields()) {
setExtendField(field, request.getAttribute(field));
}
}
/**
* 对扩展字段进行赋值
*
* @param field 字段名
* @param value 值
*/
public void setExtendField(String field, Object value) {
if (currentTemplateBeanName == null || StringUtils.isEmpty(currentTemplateBeanName.get())) {
return;
}
AbstractServiceImpl abstractService = getServiceImpl(currentTemplateBeanName.get(), AbstractServiceImpl.class);
abstractService.getExtendFieldMap().put(field, value);
}
protected String getServiceName() throws AnnotationException {
Class serviceClass = this.getClass();
if (serviceClass.isAnnotationPresent(Service.class)) {
Service service = this.getClass().getAnnotation(Service.class);
if (service != null) {
return service.value();
}
throwException("Has no Service annotation.");
}
if (serviceClass.isAnnotationPresent(Component.class)) {
Component component = this.getClass().getAnnotation(Component.class);
if (component != null) {
return component.value();
}
throwException("Has no Component annotation.");
}
LOGGER.error("Has no annotation.");
return null;
}
/**
* 根据品类模板，对poiId进行分组
*
* @param poiIds
* @return
*/
public Map<Long, List<Long>> groupPoiIds(List<Long> poiIds) {
Map<Long, List<Long>> map = null;
map = templateFunction.groupPoiIds(poiIds);
return map;
}
private void throwException(String message) throws AnnotationException {
message = this.getClass() + "||" + message;
LOGGER.error(message);
throw new AnnotationException(message);
}
}
5、在springContext.xml中声明TemplateBeanFactory
<bean class="com.baidu.nuomi.tpl.spring.TemplateBeanFactory"/>
TemplateBeanFactory的完整代码，包括模板变化时的刷新
/**
* Bean工厂，创建在模板中定义的服务实例，填充业务参数和扩展字段
* 定时刷新，如发现模板定义中的服务有变化，则刷新spring上下文中的实例.
* User: mazhen01
* Date: 2016/3/1
* Time: 16:46
*/
public class TemplateBeanFactory implements ApplicationContextAware {
private DefaultListableBeanFactory springFactory;
private static final Logger LOGGER = LoggerFactory.getLogger(TemplateBeanFactory.class);
@Autowired
TemplateFunction templateFunction;
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
setSpringFactory(applicationContext);
templateFunction.init();
loadTemplateBeanDefinitions(templateFunction.getAllTemplateEntity());
}
/**
* 刷新模板bean
*/
public void refreshTemplateBeans(List<TemplateEntity> changedTemplates) {
LOGGER.info("Refresh changed template beans start.");
if(CollectionUtils.isEmpty(changedTemplates)){
LOGGER.info("no template beans is changed");
return;
}
destroyTemplateBeans(changedTemplates);
loadTemplateBeanDefinitions(changedTemplates);
LOGGER.info("Refresh changed template beans end.");
}
/**
* 根据应用使用的不同applicationContext，获取BeanFactory
*
* @param applicationContext 应用使用的applicationContext
*/
private void setSpringFactory(ApplicationContext applicationContext) {
if (applicationContext instanceof AbstractRefreshableApplicationContext) {
// suit both XmlWebApplicationContext and ClassPathXmlApplicationContext
AbstractRefreshableApplicationContext springContext = (AbstractRefreshableApplicationContext) applicationContext;
if (!(springContext.getBeanFactory() instanceof DefaultListableBeanFactory)) {
LOGGER.error("No suitable bean factory! The current factory class is {}",
springContext.getBeanFactory().getClass());
}
springFactory = (DefaultListableBeanFactory) springContext.getBeanFactory();
} else if (applicationContext instanceof GenericApplicationContext) {
// suit GenericApplicationContext
GenericApplicationContext springContext = (GenericApplicationContext) applicationContext;
springFactory = springContext.getDefaultListableBeanFactory();
} else {
LOGGER.error("No suitable application context! The current context class is {}",
applicationContext.getClass());
}
}
/**
* 将模板中定义的service，填充业务参数和扩展字段，添加到BeanFactory的definition中
*/
private void loadTemplateBeanDefinitions(List<TemplateEntity> templateEntityList) {
if (CollectionUtils.isEmpty(templateEntityList)) {
LOGGER.warn("");
return;
}
for (TemplateEntity templateEntity : templateEntityList) {
if (templateEntity == null || CollectionUtils.isEmpty(templateEntity.getServiceList())) {
continue;
}
Long templateId = templateEntity.getIndustryId();
for (ServiceEntity serviceEntity : templateEntity.getServiceList()) {
registerBeanDefinition(templateId.toString(), serviceEntity);
}
}
}
/**
* 根据service信息，创建BeanDefinition
*
* @param templateId 模板ID
* @param serviceEntity service信息
*/
private void registerBeanDefinition(String templateId, ServiceEntity serviceEntity) {
try {
if (springFactory.containsBeanDefinition(serviceEntity.getImplName())) {
//step1: 注入多个实例
String beanKey = generateTemplateBeanName(templateId, serviceEntity.getServiceName());
BeanDefinition beanDefinition = springFactory.getBeanDefinition(serviceEntity.getImplName());
String className = beanDefinition.getBeanClassName();
Class c = null;
try {
c = Class.forName(className);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(className);
beanDefinitionBuilder.getBeanDefinition().setAttribute("id", beanKey);
springFactory.registerBeanDefinition(
beanKey, beanDefinitionBuilder.getBeanDefinition());
LOGGER.info("Register bean definition successfully. beanName:{}, implName:{}",
generateTemplateBeanName(templateId, serviceEntity.getServiceName()), serviceEntity.getImplName());
//step2: 为实例自动化注入属性
Object bean = springFactory.getBean(beanKey, c);
injectParamVaules(bean, c, serviceEntity);
}
} catch (NoSuchBeanDefinitionException ex) {
LOGGER.info("No bean definition in spring factory. implName:{}", serviceEntity.getImplName());
} catch (BeanDefinitionStoreException ex) {
LOGGER.info("Register bean definition wrong. beanName:{}, implName:{}",
generateTemplateBeanName(templateId, serviceEntity.getServiceName()), serviceEntity.getImplName());
}
}
/**
* 为bean实例注入业务参数和扩展字段
*
* @param bean
* @param requiredType
* @param serviceEntity
* @param <T>
*/
private <T> void injectParamVaules(Object bean, Class<T> requiredType, ServiceEntity serviceEntity) {
if (requiredType.isAnnotationPresent(TemplateService.class)) {
Field[] fields = requiredType.getDeclaredFields(); //获取类的所有属性
for (Field field : fields) {
// 注入业务参数
if (field.isAnnotationPresent(TemplateBizParam.class)) {
field.setAccessible(true);
try {
if ((serviceEntity.getBizParamMap() != null) && (serviceEntity.getBizParamMap().containsKey(field.getName()))) {
field.set(bean, serviceEntity.getBizParamMap().get(field.getName()));
LOGGER.info("inject biz param value successfully, paramName = {}, value = {}", field.getName(), serviceEntity.getBizParamMap().get(field.getName()));
}
} catch (IllegalAccessException e) {
LOGGER.error("inject biz param failed. {}", e.getMessage());
e.printStackTrace();
}
}
}
Class<AbstractService> superClass = getSuperClass(requiredType);
if(superClass != null) {
Field[] superFields = superClass.getDeclaredFields(); //获取类的所有属性
for (Field field : superFields) {
// 注入扩展字段
if (field.isAnnotationPresent(TemplateExtendFields.class)) {
field.setAccessible(true);
try {
if(serviceEntity.getExtendFields() != null){
field.set(bean, serviceEntity.getExtendFields());
LOGGER.info("inject extend fields successfully, extendFields = {}", serviceEntity.getExtendFields());
}
} catch (IllegalAccessException e) {
LOGGER.error("inject extend fields failed. {}", e.getMessage());
e.printStackTrace();
}
}
}
}
}
}
private Class<AbstractService> getSuperClass(Class clazz) {
if (!AbstractService.class.isAssignableFrom(clazz)) {
LOGGER.info("super class is null");
return null;
}
Class<? extends AbstractService> superClass = clazz.getSuperclass();
if (AbstractService.class != superClass) {
superClass = getSuperClass(superClass);
}
return (Class<AbstractService>) superClass;
}
/***
* 销毁模板bean
*/
private void destroyTemplateBeans(List<TemplateEntity> changedTemplates) {
if (CollectionUtils.isEmpty(changedTemplates)) {
LOGGER.warn("");
return;
}
for (TemplateEntity templateEntity : changedTemplates) {
if (templateEntity == null || CollectionUtils.isEmpty(templateEntity.getServiceList())) {
continue;
}
String templateId = templateEntity.getIndustryId().toString();
for (ServiceEntity serviceEntity : templateEntity.getServiceList()) {
if (springFactory.containsSingleton(generateTemplateBeanName(templateId, serviceEntity.getServiceName()))) {
// springFactory.destroySingleton(generateTemplateBeanName(templateId, serviceEntity.getServiceName())); 不需要显示的destroy方法，removeBeanDefinition中已调用此方法了
springFactory.removeBeanDefinition(generateTemplateBeanName(templateId, serviceEntity.getServiceName()));
LOGGER.info("destroy template beans successfully for beanName = {}", generateTemplateBeanName(templateId, serviceEntity.getServiceName()));
}
}
}
}
/**
* 从springFactory中获取bean
*
* @param name bean名称
* @param requiredType bean类型
* @param <T>
* @return
* @throws BeansException
*/
public <T> T getBean(String name, Class<T> requiredType) throws BeansException {
return springFactory.getBean(name, requiredType);
}
;
/**
* 生成模板service实例名称
*
* @param templateId 模板ID
* @param serviceName service名称
* @return
*/
public static final String generateTemplateBeanName(String templateId, String serviceName) {
StringBuilder builder = new StringBuilder(serviceName);
builder.append("_");
builder.append(templateId);
return builder.toString();
}
}