继续上一篇说的loadBeanDefinitions(EncodedResource encodedResource)方法,
/**
* Load bean definitions from the specified XML file.
* @param encodedResource the resource descriptor for the XML file,
* allowing to specify an encoding to use for parsing the file
* @return the number of bean definitions found
* @throws BeanDefinitionStoreException in case of loading or parsing errors
*/
public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
Assert.notNull(encodedResource, "EncodedResource must not be null");
if (logger.isTraceEnabled()) {
logger.trace("Loading XML bean definitions from " + encodedResource);
}
Set currentResources = this.resourcesCurrentlyBeingLoaded.get();
if (currentResources == null) {
currentResources = new HashSet<>(4);
this.resourcesCurrentlyBeingLoaded.set(currentResources);
}
if (!currentResources.add(encodedResource)) {
throw new BeanDefinitionStoreException(
"Detected cyclic loading of " + encodedResource + " - check your import definitions!");
}
try {
InputStream inputStream = encodedResource.getResource().getInputStream();
try {
InputSource inputSource = new InputSource(inputStream);
if (encodedResource.getEncoding() != null) {
inputSource.setEncoding(encodedResource.getEncoding());
}
return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
}
finally {
inputStream.close();
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"IOException parsing XML document from " + encodedResource.getResource(), ex);
}
finally {
currentResources.remove(encodedResource);
if (currentResources.isEmpty()) {
this.resourcesCurrentlyBeingLoaded.remove();
}
}
}
获取inputSource,以及Resource对象,执行doLoadBeanDefinitions(inputSource, encodedResource.getResource());
继续往下看这方法:
/**
* Actually load bean definitions from the specified XML file.
* @param inputSource the SAX InputSource to read from
* @param resource the resource descriptor for the XML file
* @return the number of bean definitions found
* @throws BeanDefinitionStoreException in case of loading or parsing errors
* @see #doLoadDocument
* @see #registerBeanDefinitions
*/
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
Document doc = doLoadDocument(inputSource, resource);
int count = registerBeanDefinitions(doc, resource);
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + count + " bean definitions from " + resource);
}
return count;
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (SAXParseException ex) {
throw new XmlBeanDefinitionStoreException(resource.getDescription(),
"Line " + ex.getLineNumber() + " in XML document from " + resource + " is invalid", ex);
}
catch (SAXException ex) {
throw new XmlBeanDefinitionStoreException(resource.getDescription(),
"XML document from " + resource + " is invalid", ex);
}
catch (ParserConfigurationException ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"Parser configuration exception parsing XML from " + resource, ex);
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"IOException parsing XML document from " + resource, ex);
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"Unexpected exception parsing XML document from " + resource, ex);
}
}
2个方法的执行,doLoadDocument(inputSource, resource),registerBeanDefinitions(doc, resource),
先看下**doLoadDocument(inputSource, resource)**这方法:
/**
* Actually load the specified document using the configured DocumentLoader.
* @param inputSource the SAX InputSource to read from
* @param resource the resource descriptor for the XML file
* @return the DOM Document
* @throws Exception when thrown from the DocumentLoader
* @see #setDocumentLoader
* @see DocumentLoader#loadDocument
*/
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
这边大概的意思主要是xml文件的格式是否正确,需要个验证模式,XSD或者DTD,是xml文件的一部分,
看下xsd即xml schema语言的表现形式
xmlns=“http://www.springframework.org/schema/beans” 名称空间
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
xml schema文档的存储位置,一部分是uri,另外一部分是文件位置
继续往下走
/*
* Return the EntityResolver to use, building a default resolver
* if none specified.
*/
protected EntityResolver getEntityResolver() {`在这里插入代码片`
if (this.entityResolver == null) {
// Determine default EntityResolver to use.
ResourceLoader resourceLoader = getResourceLoader();
if (resourceLoader != null) {
this.entityResolver = new ResourceEntityResolver(resourceLoader);
}
else {
this.entityResolver = new DelegatingEntityResolver(getBeanClassLoader());
}
}
return this.entityResolver;
}
下面是**new ResourceEntityResolver(resourceLoader)**的具体执行
/**
* Create a new DelegatingEntityResolver that delegates to
* a default {@link BeansDtdResolver} and a default {@link PluggableSchemaResolver}.
* Configures the {@link PluggableSchemaResolver} with the supplied
* {@link ClassLoader}.
* @param classLoader the ClassLoader to use for loading
* (can be {@code null}) to use the default ClassLoader)
*/
public DelegatingEntityResolver(@Nullable ClassLoader classLoader) {
this.dtdResolver = new BeansDtdResolver();
this.schemaResolver = new PluggableSchemaResolver(classLoader);
}
其实就是生成2种文件格式的解析器
ResourceLoader resourceLoader = getResourceLoader();
这边有必要说下getResourceLoader()这方法是在父类定义的,子类直接继承调用了,关于他的赋值,是在xmlFactory类初始化XmlBeanDefinitionReader的时候,spring框架里面很多地方用了这种方式,所以看源码的时候,要看仔细了,不然都不知道在哪set的值
private final XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(this);
/**
* Create new XmlBeanDefinitionReader for the given bean factory.
* @param registry the BeanFactory to load bean definitions into,
* in the form of a BeanDefinitionRegistry
*/
public XmlBeanDefinitionReader(BeanDefinitionRegistry registry) {
super(registry);
}
/**
* Create a new AbstractBeanDefinitionReader for the given bean factory.
* If the passed-in bean factory does not only implement the BeanDefinitionRegistry
* interface but also the ResourceLoader interface, it will be used as default
* ResourceLoader as well. This will usually be the case for
* {@link org.springframework.context.ApplicationContext} implementations.
*
If given a plain BeanDefinitionRegistry, the default ResourceLoader will be a
* {@link org.springframework.core.io.support.PathMatchingResourcePatternResolver}.
*
If the passed-in bean factory also implements {@link EnvironmentCapable} its
* environment will be used by this reader. Otherwise, the reader will initialize and
* use a {@link StandardEnvironment}. All ApplicationContext implementations are
* EnvironmentCapable, while normal BeanFactory implementations are not.
* @param registry the BeanFactory to load bean definitions into,
* in the form of a BeanDefinitionRegistry
* @see #setResourceLoader
* @see #setEnvironment
*/
protected AbstractBeanDefinitionReader(BeanDefinitionRegistry registry) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
// Determine ResourceLoader to use.
if (this.registry instanceof ResourceLoader) {
this.resourceLoader = (ResourceLoader) this.registry;
}
else {
this.resourceLoader = new PathMatchingResourcePatternResolver();
}
// Inherit Environment if possible
if (this.registry instanceof EnvironmentCapable) {
this.environment = ((EnvironmentCapable) this.registry).getEnvironment();
}
else {
this.environment = new StandardEnvironment();
}
}
继续看下getValidationModeForResource(resource)方法:
/**
* Determine the validation mode for the specified {@link Resource}.
* If no explicit validation mode has been configured, then the validation
* mode gets {@link #detectValidationMode detected} from the given resource.
* Override this method if you would like full control over the validation
* mode, even when something other than {@link #VALIDATION_AUTO} was set.
* @see #detectValidationMode
*/
protected int getValidationModeForResource(Resource resource) {
int validationModeToUse = getValidationMode();
if (validationModeToUse != VALIDATION_AUTO) {
return validationModeToUse;
}
int detectedMode = detectValidationMode(resource);
if (detectedMode != VALIDATION_AUTO) {
return detectedMode;
}
// Hmm, we didn't get a clear indication... Let's assume XSD,
// since apparently no DTD declaration has been found up until
// detection stopped (before finding the document's root tag).
return VALIDATION_XSD;
}
这方法是文件格式验证模式的获取,如果手动指定了验证模式,则使用指定的验证模式,否则使用自动检查的方式
// VALIDATION_AUTO 为 1
private int validationMode = VALIDATION_AUTO;
XmlBeanDefinitionReader该类默认的验证模式是自动的,如果想自定义的话,就调用
/**
* Set the validation mode to use. Defaults to {@link #VALIDATION_AUTO}.
* Note that this only activates or deactivates validation itself.
* If you are switching validation off for schema files, you might need to
* activate schema namespace support explicitly: see {@link #setNamespaceAware}.
*/
public void setValidationMode(int validationMode) {
this.validationMode = validationMode;
}
继续往下走,看下自动模式的执行:
/**
* Detect which kind of validation to perform on the XML file identified
* by the supplied {@link Resource}. If the file has a {@code DOCTYPE}
* definition then DTD validation is used otherwise XSD validation is assumed.
* Override this method if you would like to customize resolution
* of the {@link #VALIDATION_AUTO} mode.
*/
protected int detectValidationMode(Resource resource) {
if (resource.isOpen()) {
throw new BeanDefinitionStoreException(
"Passed-in Resource [" + resource + "] contains an open stream: " +
"cannot determine validation mode automatically. Either pass in a Resource " +
"that is able to create fresh streams, or explicitly specify the validationMode " +
"on your XmlBeanDefinitionReader instance.");
}
InputStream inputStream;
try {
inputStream = resource.getInputStream();
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"Unable to determine validation mode for [" + resource + "]: cannot open InputStream. " +
"Did you attempt to load directly from a SAX InputSource without specifying the " +
"validationMode on your XmlBeanDefinitionReader instance?", ex);
}
try {
return this.validationModeDetector.detectValidationMode(inputStream);
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("Unable to determine validation mode for [" +
resource + "]: an error occurred whilst reading from the InputStream.", ex);
}
}
/**
* Detect the validation mode for the XML document in the supplied {@link InputStream}.
* Note that the supplied {@link InputStream} is closed by this method before returning.
* @param inputStream the InputStream to parse
* @throws IOException in case of I/O failure
* @see #VALIDATION_DTD
* @see #VALIDATION_XSD
*/
public int detectValidationMode(InputStream inputStream) throws IOException {
// Peek into the file to look for DOCTYPE.
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
boolean isDtdValidated = false;
String content;
while ((content = reader.readLine()) != null) {
content = consumeCommentTokens(content);
if (this.inComment || !StringUtils.hasText(content)) {
continue;
}
if (hasDoctype(content)) {
isDtdValidated = true;
break;
}
if (hasOpeningTag(content)) {
// End of meaningful data...
break;
}
}
return (isDtdValidated ? VALIDATION_DTD : VALIDATION_XSD);
}
catch (CharConversionException ex) {
// Choked on some character encoding...
// Leave the decision up to the caller.
return VALIDATION_AUTO;
}
finally {
reader.close();
}
}
/**
* Does the content contain the DTD DOCTYPE declaration?
*/
private boolean hasDoctype(String content) {
return content.contains(DOCTYPE);
}
意思简单明了,是否包含DOCTYPE,包含的话就是DTD,否则是XSD,ok,今天就这样,下篇继续!