Springソース分析-beanの解析(3)

package io.github.binglau.bean;

import lombok.Data;

/**
 *     :
 */

@Data
public class User {
    private String userName;
    private String email;
}

package io.github.binglau;

import io.github.binglau.bean.User;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;

/**
 *     :
 */

public class UserBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {
    // Element     
    @Override
    protected Class> getBeanClass(Element element) {
        return User.class;
    }

    //   element            
    @Override
    protected void doParse(Element element, BeanDefinitionBuilder builder) {
        String userName = element.getAttribute("userName");
        String email = element.getAttribute("email");
        //          BeanDefinitionBuilder  ，       bean           beanFactory  
        if (StringUtils.hasText(userName)) {
            builder.addPropertyValue("userName", userName);
        }
        if (StringUtils.hasText(email)) {
            builder.addPropertyValue("email", email);
        }
    }
}

package io.github.binglau;

import org.springframework.beans.factory.xml.NamespaceHandlerSupport;

/**
 *     :
 */

public class MyNamespaceHandler extends NamespaceHandlerSupport {
    @Override
    public void init() {
        registerBeanDefinitionParser("user", new UserBeanDefinitionParser());
    }
}

# Spring.handlers
http\://www.binglau.com/schema/user=io.github.binglau.MyNamespaceHandler

# Spring.schemas
http\://www.binglau.com/schema/user.xsd=user-xsd.xsd

package io.github.binglau;

import io.github.binglau.bean.User;
import org.junit.Test;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;

/**
 *     :
 */

public class BeanFactoryTest {
    @Test
    public void testSimpleLoad() {
        BeanFactory context = new XmlBeanFactory(new ClassPathResource("beanFactory.xml"));
        User user = (User)context.getBean("testbean");
        System.out.println(user);
    }
}

/**
  ：
User(userName=aaa, email=bbb)
**/

    /**
     * Parse the elements at the root level in the document:
     * "import", "alias", "bean".
     * @param root the DOM root element of the document
     */
    protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
        if (delegate.isDefaultNamespace(root)) {
            NodeList nl = root.getChildNodes();
            for (int i = 0; i < nl.getLength(); i++) {
                Node node = nl.item(i);
                if (node instanceof Element) {
                    Element ele = (Element) node;
                    if (delegate.isDefaultNamespace(ele)) {
                        parseDefaultElement(ele, delegate);
                    }
                    else {
                        delegate.parseCustomElement(ele);
                    }
                }
            }
        }
        else {
            delegate.parseCustomElement(root);
        }
    }

    public BeanDefinition parseCustomElement(Element ele) {
        return parseCustomElement(ele, null);
    }
    // containingBd     bean，             null
    public BeanDefinition parseCustomElement(Element ele, BeanDefinition containingBd) {
        //          
        String namespaceUri = getNamespaceURI(ele);
        //             NamespaceHandler
        NamespaceHandler handler = this.readerContext.getNamespaceHandlerResolver().resolve(namespaceUri);
        if (handler == null) {
            error("Unable to locate Spring NamespaceHandler for XML schema namespace [" + namespaceUri + "]", ele);
            return null;
        }
        //        NamespaceHandler     
        return handler.parse(ele, new ParserContext(this.readerContext, this, containingBd));
    }

    public String getNamespaceURI(Node node) {
        return node.getNamespaceURI();
    }

    /**
     * Locate the {@link NamespaceHandler} for the supplied namespace URI
     * from the configured mappings.
     * @param namespaceUri the relevant namespace URI
     * @return the located {@link NamespaceHandler}, or {@code null} if none found
     */
    @Override
    public NamespaceHandler resolve(String namespaceUri) {
        //           handler   
        Map handlerMappings = getHandlerMappings();
        //              
        Object handlerOrClassName = handlerMappings.get(namespaceUri);
        if (handlerOrClassName == null) {
            return null;
        }
        else if (handlerOrClassName instanceof NamespaceHandler) {
            //          ，       
            return (NamespaceHandler) handlerOrClassName;
        }
        else {
            //       ，        
            String className = (String) handlerOrClassName;
            try {
                //              
                Class> handlerClass = ClassUtils.forName(className, this.classLoader);
                if (!NamespaceHandler.class.isAssignableFrom(handlerClass)) {
                    throw new FatalBeanException("Class [" + className + "] for namespace [" + namespaceUri +
                            "] does not implement the [" + NamespaceHandler.class.getName() + "] interface");
                }
                //     
                NamespaceHandler namespaceHandler = (NamespaceHandler) BeanUtils.instantiateClass(handlerClass);
                //        NamespaceHandler       
                namespaceHandler.init();
                //      
                handlerMappings.put(namespaceUri, namespaceHandler);
                return namespaceHandler;
            }
            catch (ClassNotFoundException ex) {
                throw new FatalBeanException("NamespaceHandler class [" + className + "] for namespace [" +
                        namespaceUri + "] not found", ex);
            }
            catch (LinkageError err) {
                throw new FatalBeanException("Invalid NamespaceHandler class [" + className + "] for namespace [" +
                        namespaceUri + "]: problem with handler class file or dependent class", err);
            }
        }
    }

    public void init() {
        registerBeanDefinitionParser("user", new UserBeanDefinitionParser());
    }

    /**
     * Load the specified NamespaceHandler mappings lazily.
     */
    private Map getHandlerMappings() {
        //               
        if (this.handlerMappings == null) {
            synchronized (this) {
                if (this.handlerMappings == null) {
                    try {
                        // this.handlerMappingsLocation             META-INF/Spring.handlers
                        Properties mappings =
                                PropertiesLoaderUtils.loadAllProperties(this.handlerMappingsLocation, this.classLoader);
                        if (logger.isDebugEnabled()) {
                            logger.debug("Loaded NamespaceHandler mappings: " + mappings);
                        }
                        Map handlerMappings = new ConcurrentHashMap(mappings.size());
                        //   Properties         Map     handlerMappings  
                        CollectionUtils.mergePropertiesIntoMap(mappings, handlerMappings);
                        this.handlerMappings = handlerMappings;
                    }
                    catch (IOException ex) {
                        throw new IllegalStateException(
                                "Unable to load NamespaceHandler mappings from location [" + this.handlerMappingsLocation + "]", ex);
                    }
                }
            }
        }
        return this.handlerMappings;
    }

    /**
     * Parses the supplied {@link Element} by delegating to the {@link BeanDefinitionParser} that is
     * registered for that {@link Element}.
     */
    @Override
    public BeanDefinition parse(Element element, ParserContext parserContext) {
        //             
        return findParserForElement(element, parserContext).parse(element, parserContext);
    }
    /**
     * Locates the {@link BeanDefinitionParser} from the register implementations using
     * the local name of the supplied {@link Element}.
     */
    private BeanDefinitionParser findParserForElement(Element element, ParserContext parserContext) {
        //       ，        user，        ，    localName   user
        String localName = parserContext.getDelegate().getLocalName(element);
        //    user         ，     
        // registerBeanDefinitionParser("user", new UserBeanDefinitionParser())       
        BeanDefinitionParser parser = this.parsers.get(localName);
        if (parser == null) {
            parserContext.getReaderContext().fatal(
                    "Cannot locate BeanDefinitionParser for element [" + localName + "]", element);
        }
        return parser;
    }

    @Override
    public final BeanDefinition parse(Element element, ParserContext parserContext) {
        //        
        AbstractBeanDefinition definition = parseInternal(element, parserContext);
        if (definition != null && !parserContext.isNested()) {
            try {
                String id = resolveId(element, definition, parserContext);
                if (!StringUtils.hasText(id)) {
                    parserContext.getReaderContext().error(
                            "Id is required for element '" + parserContext.getDelegate().getLocalName(element)
                                    + "' when used as a top-level tag", element);
                }
                String[] aliases = null;
                if (shouldParseNameAsAliases()) {
                    String name = element.getAttribute(NAME_ATTRIBUTE);
                    if (StringUtils.hasLength(name)) {
                        aliases = StringUtils.trimArrayElements(StringUtils.commaDelimitedListToStringArray(name));
                    }
                }
                //   AbstractBeanDefinition     BeanDefinitionHolder    
                BeanDefinitionHolder holder = new BeanDefinitionHolder(definition, id, aliases);
                registerBeanDefinition(holder, parserContext.getRegistry());
                if (shouldFireEvents()) {
                    //             
                    BeanComponentDefinition componentDefinition = new BeanComponentDefinition(holder);
                    postProcessComponentDefinition(componentDefinition);
                    parserContext.registerComponent(componentDefinition);
                }
            }
            catch (BeanDefinitionStoreException ex) {
                parserContext.getReaderContext().error(ex.getMessage(), element);
                return null;
            }
        }
        return definition;
    }

    /**
     * Creates a {@link BeanDefinitionBuilder} instance for the
     * {@link #getBeanClass bean Class} and passes it to the
     * {@link #doParse} strategy method.
     * @param element the element that is to be parsed into a single BeanDefinition
     * @param parserContext the object encapsulating the current state of the parsing process
     * @return the BeanDefinition resulting from the parsing of the supplied {@link Element}
     * @throws IllegalStateException if the bean {@link Class} returned from
     * {@link #getBeanClass(org.w3c.dom.Element)} is {@code null}
     * @see #doParse
     */
    @Override
    protected final AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition();
        String parentName = getParentName(element);
        if (parentName != null) {
            builder.getRawBeanDefinition().setParentName(parentName);
        }
        //           class，             UserBeanDefinitionParser    getBeanClass   
        Class> beanClass = getBeanClass(element);
        if (beanClass != null) {
            builder.getRawBeanDefinition().setBeanClass(beanClass);
        }
        else {
            //         getBeanClass               getBeanClassName   
            String beanClassName = getBeanClassName(element);
            if (beanClassName != null) {
                builder.getRawBeanDefinition().setBeanClassName(beanClassName);
            }
        }
        builder.getRawBeanDefinition().setSource(parserContext.extractSource(element));
        if (parserContext.isNested()) {
            //             scope   
            // Inner bean definition must receive same scope as containing bean.
            builder.setScope(parserContext.getContainingBeanDefinition().getScope());
        }
        if (parserContext.isDefaultLazyInit()) {
            // Default-lazy-init applies to custom bean definitions as well.
            //       
            builder.setLazyInit(true);
        }
        //         doParse       
        doParse(element, parserContext, builder);
        return builder.getBeanDefinition();
    }

    protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
        doParse(element, builder);
    }