XmlWebApplicationContext的loadBeanDefinitions
此时到了真正的加载xml到spring过程
大概分为加载xml资源，然后xmlreader去解析相应的配置生成BeanDefinition，注册到spring工程内存中
1、xml资源加载
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
// Create a new XmlBeanDefinitionReader for the given BeanFactory.
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
// Configure the bean definition reader with this context's
// resource loading environment.
beanDefinitionReader.setEnvironment(getEnvironment());
beanDefinitionReader.setResourceLoader(this);
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
// Allow a subclass to provide custom initialization of the reader,
// then proceed with actually loading the bean definitions.
initBeanDefinitionReader(beanDefinitionReader);
loadBeanDefinitions(beanDefinitionReader);
}
具体的XmlBeanDefinitionReader继承图
这个类需要两个对象的功能，即正合了资源加载和注册的两个功能
注册就是实现了BeanDifinitionRegisitry DafaultListableBeanFactory工厂类，
和实现了资源加载的AbstractRefreshableApplicationContext工厂类，
可见spring的工厂类实质是资源加载获取跟获取BeanDefinie并注册两个类
具体的XmlBeanDefinitionReader的初始化如上
因为DefaultListableBeanFactory没有实现ResourceLoader，所以设置ResourceLoader是
this.resourceLoader = new PathMatchingResourcePatternResolver();
同理Envrioment也
this.environment = new StandardEnvironment();
但是到
loadBeanDefinitions时候
// resource loading environment. beanDefinitionReader.setEnvironment(getEnvironment()); beanDefinitionReader.setResourceLoader(this); beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
又设置成当前Factory的Enviroment和ResourceLoader
到loadBeanDefinitions(beanDefinitionReader)开始执行加载Resource
protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws IOException {
String[] configLocations = getConfigLocations();
if (configLocations != null) {
for (String configLocation : configLocations) {
reader.loadBeanDefinitions(configLocation);
}
}
}
AbstractBeanDefinitionReader
public int loadBeanDefinitions(String location) throws BeanDefinitionStoreException {
return loadBeanDefinitions(location, null);
}
public int loadBeanDefinitions(String location, Set<Resource> actualResources) throws BeanDefinitionStoreException {
ResourceLoader resourceLoader = getResourceLoader();
if (resourceLoader == null) {
throw new BeanDefinitionStoreException(
"Cannot import bean definitions from location [" + location + "]: no ResourceLoader available");
}
if (resourceLoader instanceof ResourcePatternResolver) {
// Resource pattern matching available.
try {
Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location);
int loadCount = loadBeanDefinitions(resources);
if (actualResources != null) {
for (Resource resource : resources) {
actualResources.add(resource);
}
}
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + loadCount + " bean definitions from location pattern [" + location + "]");
}
return loadCount;
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"Could not resolve bean definition resource pattern [" + location + "]", ex);
}
}
else {
// Can only load single resources by absolute URL.
Resource resource = resourceLoader.getResource(location);
int loadCount = loadBeanDefinitions(resource);
if (actualResources != null) {
actualResources.add(resource);
}
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + loadCount + " bean definitions from location [" + location + "]");
}
return loadCount;
}
}
AbstractApplicationContext:
@Override
public Resource[] getResources(String locationPattern) throws IOException {
return this.resourcePatternResolver.getResources(locationPattern);
}
AbstractApplicationContext的resourcePatternResolver是
PathMatchingResourcePatternResolver
public Resource[] getResources(String locationPattern) throws IOException {
Assert.notNull(locationPattern, "Location pattern must not be null");
//处理以classpath*开头的路径:
if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
// a class path resource (multiple resources for same name possible)
if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
// a class path resource pattern
return findPathMatchingResources(locationPattern);
}
else {
// all class path resources with the given name
return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
}
}
else {
//classpath:开头的路径
// Only look for a pattern after a prefix here
// (to not get fooled by a pattern symbol in a strange prefix).
int prefixEnd = locationPattern.indexOf(":") + 1;
if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
// a file pattern
return findPathMatchingResources(locationPattern);
}
else {
// a single resource with the given name
return new Resource[] {getResourceLoader().getResource(locationPattern)};
}
}
}
protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
String rootDirPath = determineRootDir(locationPattern);
String subPattern = locationPattern.substring(rootDirPath.length());
Resource[] rootDirResources = getResources(rootDirPath);
Set<Resource> result = new LinkedHashSet<Resource>(16);
for (Resource rootDirResource : rootDirResources) {
rootDirResource = resolveRootDirResource(rootDirResource);
if (rootDirResource.getURL().getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirResource, subPattern, getPathMatcher()));
}
else if (isJarResource(rootDirResource)) {
result.addAll(doFindPathMatchingJarResources(rootDirResource, subPattern));
}
else {
result.addAll(doFindPathMatchingFileResources(rootDirResource, subPattern));
}
}
if (logger.isDebugEnabled()) {
logger.debug("Resolved location pattern [" + locationPattern + "] to resources " + result);
}
return result.toArray(new Resource[result.size()]);
}
public boolean isPattern(String path) {
//判断路径中是否包含：* ？
return (path.indexOf('*') != -1 || path.indexOf('?') != -1);
}
以classpath:*.xml为例子
然后获取到rootDirPath：classpath: , subPattern:*.xml
然后再次调用 findPathMatchingResources 走
return new Resource[] {getResourceLoader().getResource(locationPattern)};
调用到DefaultResourceLoader
public Resource getResource(String location) {
Assert.notNull(location, "Location must not be null");
if (location.startsWith("/")) {
return getResourceByPath(location);
}
else if (location.startsWith(CLASSPATH_URL_PREFIX)) {
return new ClassPathResource(location.substring(CLASSPATH_URL_PREFIX.length()), getClassLoader());
}
else {
try {
// Try to parse the location as a URL...
URL url = new URL(location);
return new UrlResource(url);
}
catch (MalformedURLException ex) {
// No URL -> resolve as resource path.
return getResourceByPath(location);
}
}
}
然后为“”所以走
new ClassPathResource(location.substring(CLASSPATH_URL_PREFIX.length()), getClassLoader());
最后回到AbstractBeanDefinitionReader的
public int loadBeanDefinitions(String location, Set<Resource> actualResources) throws BeanDefinitionStoreException {
ResourceLoader resourceLoader = getResourceLoader();
if (resourceLoader == null) {
throw new BeanDefinitionStoreException(
"Cannot import bean definitions from location [" + location + "]: no ResourceLoader available");
}
if (resourceLoader instanceof ResourcePatternResolver) {
// Resource pattern matching available.
try {
Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location);
int loadCount = loadBeanDefinitions(resources);
if (actualResources != null) {
for (Resource resource : resources) {
actualResources.add(resource);
}
}
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + loadCount + " bean definitions from location pattern [" + location + "]");
}
return loadCount;
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"Could not resolve bean definition resource pattern [" + location + "]", ex);
}
}
else {
// Can only load single resources by absolute URL.
Resource resource = resourceLoader.getResource(location);
int loadCount = loadBeanDefinitions(resource);
if (actualResources != null) {
actualResources.add(resource);
}
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + loadCount + " bean definitions from location [" + location + "]");
}
return loadCount;
}
}
public int loadBeanDefinitions(Resource... resources) throws BeanDefinitionStoreException {
Assert.notNull(resources, "Resource array must not be null");
int counter = 0;
for (Resource resource : resources) {
counter += loadBeanDefinitions(resource);
}
return counter;
}
XmlBeanDefinitionReader
public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {
return loadBeanDefinitions(new EncodedResource(resource));
}
public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
Assert.notNull(encodedResource, "EncodedResource must not be null");
if (logger.isInfoEnabled()) {
logger.info("Loading XML bean definitions from " + encodedResource.getResource());
}
Set<EncodedResource> currentResources = this.resourcesCurrentlyBeingLoaded.get();
//讲Resource放到本地的ThreadLocal对象中去
if (currentResources == null) {
currentResources = new HashSet<EncodedResource>(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 {
//读取资源获取流传入doLoadBeanDefinitions
InputSource inputSource = new InputSource(inputStream);
if (encodedResource.getEncoding() != null) {
inputSource.setEncoding(encodedResource.getEncoding());
}
//致此处文件流获取到啦，开始读取配置
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();
}
}
}
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
Document doc = doLoadDocument(inputSource, resource);
return registerBeanDefinitions(doc, resource);
}
}
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
protected EntityResolver getEntityResolver() {
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;
}
继而出现了新的几个类：
EntityResolver ： 加载dtd、xsd文件的资源加载类
ErrorHandler ： 在xml解析过程出错处理报告错误的处理类
首先看下EntityResolver：
ResourceEntityResolver
这个是负责获取dtd、xsd的文件inputsource流的，寻找spring xml中的引用的dtd、xsd的文件
DelegatingEntityResolver中引入了这个两个对象做处理
ErrorHandler：
public class SimpleSaxErrorHandler implements ErrorHandler {
private final Log logger;
/**
* Create a new SimpleSaxErrorHandler for the given
* Commons Logging logger instance.
*/
public SimpleSaxErrorHandler(Log logger) {
this.logger = logger;
}
@Override
public void warning(SAXParseException ex) throws SAXException {
logger.warn("Ignored XML validation warning", ex);
}
@Override
public void error(SAXParseException ex) throws SAXException {
throw ex;
}
@Override
public void fatalError(SAXParseException ex) throws SAXException {
throw ex;
}
根据xml内容去决定是否dtd的还是xsd的验证模式
public static final int VALIDATION_XSD = 3; //xsd验证
public static final int VALIDATION_DTD = 2; //dtd验证
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);
}
}
验证xml的XmlValidationModeDetector 如下：
/*
* Copyright 2002-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.util.xml;
import java.io.BufferedReader;
import java.io.CharConversionException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.springframework.util.StringUtils;
/**
* Detects whether an XML stream is using DTD- or XSD-based validation.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
*/
public class XmlValidationModeDetector {
/**
* Indicates that the validation should be disabled.
*/
public static final int VALIDATION_NONE = 0;
/**
* Indicates that the validation mode should be auto-guessed, since we cannot find
* a clear indication (probably choked on some special characters, or the like).
*/
public static final int VALIDATION_AUTO = 1;
/**
* Indicates that DTD validation should be used (we found a "DOCTYPE" declaration).
*/
public static final int VALIDATION_DTD = 2;
/**
* Indicates that XSD validation should be used (found no "DOCTYPE" declaration).
*/
public static final int VALIDATION_XSD = 3;
/**
* The token in a XML document that declares the DTD to use for validation
* and thus that DTD validation is being used.
*/
private static final String DOCTYPE = "DOCTYPE";
/**
* The token that indicates the start of an XML comment.
*/
private static final String START_COMMENT = "<!--";
/**
* The token that indicates the end of an XML comment.
*/
private static final String END_COMMENT = "-->";
/**
* Indicates whether or not the current parse position is inside an XML comment.
*/
private boolean inComment;
/**
* 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 the DTD DOCTYPE declaration?
*/
private boolean hasDoctype(String content) {
return content.contains(DOCTYPE);
}
/**
* Does the supplied content contain an XML opening tag. If the parse state is currently
* in an XML comment then this method always returns false. It is expected that all comment
* tokens will have consumed for the supplied content before passing the remainder to this method.
*/
private boolean hasOpeningTag(String content) {
if (this.inComment) {
return false;
}
int openTagIndex = content.indexOf('<');
return (openTagIndex > -1 && (content.length() > openTagIndex + 1) &&
Character.isLetter(content.charAt(openTagIndex + 1)));
}
/**
* Consumes all the leading comment data in the given String and returns the remaining content, which
* may be empty since the supplied content might be all comment data. For our purposes it is only important
* to strip leading comment content on a line since the first piece of non comment content will be either
* the DOCTYPE declaration or the root element of the document.
*/
private String consumeCommentTokens(String line) {
if (!line.contains(START_COMMENT) && !line.contains(END_COMMENT)) {
return line;
}
while ((line = consume(line)) != null) {
if (!this.inComment && !line.trim().startsWith(START_COMMENT)) {
return line;
}
}
return line;
}
/**
* Consume the next comment token, update the "inComment" flag
* and return the remaining content.
*/
private String consume(String line) {
int index = (this.inComment ? endComment(line) : startComment(line));
return (index == -1 ? null : line.substring(index));
}
/**
* Try to consume the {@link #START_COMMENT} token.
* @see #commentToken(String, String, boolean)
*/
private int startComment(String line) {
return commentToken(line, START_COMMENT, true);
}
private int endComment(String line) {
return commentToken(line, END_COMMENT, false);
}
/**
* Try to consume the supplied token against the supplied content and update the
* in comment parse state to the supplied value. Returns the index into the content
* which is after the token or -1 if the token is not found.
*/
private int commentToken(String line, String token, boolean inCommentIfPresent) {
int index = line.indexOf(token);
if (index > - 1) {
this.inComment = inCommentIfPresent;
}
return (index == -1 ? index : index + token.length());
}
}
然后 DefaultDocumentLoader 的loadDocument获取Document对象
public Document loadDocument(InputSource inputSource, EntityResolver entityResolver,
ErrorHandler errorHandler, int validationMode, boolean namespaceAware) throws Exception {
//创建DocumentBuilderFactory
DocumentBuilderFactory factory = createDocumentBuilderFactory(validationMode, namespaceAware);
if (logger.isDebugEnabled()) {
logger.debug("Using JAXP provider [" + factory.getClass().getName() + "]");
}
//创建DocumentBuilder
DocumentBuilder builder = createDocumentBuilder(factory, entityResolver, errorHandler);
//创建Document
return builder.parse(inputSource);
}
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
Document doc = doLoadDocument(inputSource, resource);
return registerBeanDefinitions(doc, resource);
}
}
注册BeanDefinitions:XmlBeanDefinitionReader
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
int countBefore = getRegistry().getBeanDefinitionCount();
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
return getRegistry().getBeanDefinitionCount() - countBefore;
}
注册BeanDefinitionDocumentReader
private Class<?> documentReaderClass = DefaultBeanDefinitionDocumentReader.class;
protected BeanDefinitionDocumentReader createBeanDefinitionDocumentReader() {
return BeanDefinitionDocumentReader.class.cast(BeanUtils.instantiateClass(this.documentReaderClass));
}
public XmlReaderContext createReaderContext(Resource resource) {
return new XmlReaderContext(resource, this.problemReporter, this.eventListener,
this.sourceExtractor, this, getNamespaceHandlerResolver());
}
public NamespaceHandlerResolver getNamespaceHandlerResolver() {
if (this.namespaceHandlerResolver == null) {
this.namespaceHandlerResolver = createDefaultNamespaceHandlerResolver();
}
return this.namespaceHandlerResolver;
}
protected NamespaceHandlerResolver createDefaultNamespaceHandlerResolver() {
return new DefaultNamespaceHandlerResolver(getResourceLoader().getClassLoader());
}
DefaultBeanDefinitionDocumentReader 的registerBeanDefinitions
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
logger.debug("Loading bean definitions");
Element root = doc.getDocumentElement();
doRegisterBeanDefinitions(root);
}
转载于:https://my.oschina.net/u/867830/blog/824217