2.3 最简单的例子
public class MyTestBean {
private String testStr = "testStr";
public String getTestStr() {
return this.testStr;
}
public void setTestStr(String str) {
this.testStr = str;
}
}
<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="myTestBean" class="com.spring.MyTestBean"/>
</beans>
public class TestClass {
@Test
public void test() throws IOException {
// ClassPathResource
Resource res = new ClassPathResource("beanFactory.xml");
BeanFactory beanFactory = new XBeanXmlBeanFactory(res);
MyTestBean myTestBean = (MyTestBean) beanFactory.getBean("myTestBean");
System.out.println(myTestBean.getTestStr());
}
}
2.4 Spring 核心类介绍
2.5 容器的基础 xmlBeanFactory
2.5.1 配置文件封装
- IOC 的第一步就是加载配置文件，获取配置文件的信息，去找到定义的对应的 bean
- Resource 的作用是将配置文件资源进行统一封装，不管你是 File/URL 等配置，都统一封装为 Resource，供 BeanFactory 使用
- FileSystemResource：需要给出文件的路径信息即可获取到文件的配置，因为实现上是调用了 File.getInputStream () 方法；或给出文件在 classes 当中的路径即可；
- ClassPathResource：加载编译目录当中的配置文件，不需要路径信息，直接输入文件名称即可；若找不到，则去 classes 里面看文件是否存在，若不存在，需要配置到编译路径当中
- UrlResource:
可以访问 file/http/ftp 资源信息，可以通过获取某个类的 classLoader 即可得到对应的 classes 路径信息，就可以通过 name 来获取配置文件所在的路径的 URL
- ServletContextResource: 暂时不研究
//FileSystemResource
Resource fileRes1 = new FileSystemResource(
"/Users/admin/projects/myPro/src/resource/beanFactory.xml");
Resource fileRes2 = new FileSystemResource("src/resource/beanFactory.xml");
// ClassPathResource
Resource classRes = new ClassPathResource("beanFactory.xml");
// UrlResource
//输出结果:/Users/admin/projects/myPro/target/classes/beanFactory.xml
System.out.println(TestClass.class.getClassLoader().getResource("beanFactory.xml").getPath());
Resource urlRes = new UrlResource(
TestClass.class.getClassLoader().getResource("beanFactory.xml"));
2.5.2 加载 bean
BeanFactory beanFactory = new XBeanXmlBeanFactory(res);
MyTestBean myTestBean = (MyTestBean) beanFactory.getBean("myTestBean");
封装资源文件
- 这个工作是由 XmlBeanDefinitionReader 完成的
- 首先封装 Resource 为 EncodedResource，防止出现编码不一的情况，使用默认的 encode；
- 然后再 loadBeanDefinitions
public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {
return loadBeanDefinitions(new EncodedResource(resource));
}
loadBeanDefinitions
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();
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());
}
// 真正开始解析Bean的信息
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 {
// 解析xml to Document
Document doc = doLoadDocument(inputSource, resource);
// 解析Document，注册Bean信息
return registerBeanDefinitions(doc, resource);
}
}
解析 xml
- 将 EncodedResource 转换为 InputStream
- 将 InputStream 转换为 InputSource
- 用 SAX 解析 InputSource，获取 Document，返回 xml 里面的 Bean 信息
- 获取 EntityResolver；解析 DTD 文件的声明
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;
}
- 解析 InputSource 的时候首先获取验证模式是 XSD 还是 DTD
protected int getValidationModeForResource(Resource resource) {
int validationModeToUse = getValidationMode();
if (validationModeToUse != VALIDATION_AUTO) {
return validationModeToUse;
}
int detectedMode = detectValidationMode(resource);
if (detectedMode != VALIDATION_AUTO) {
return detectedMode;
}
return VALIDATION_XSD;
}
注册 Bean 信息
- 获取 Document 信息之后，第一步先取 ROOT 节点，再根据 root 节点，注册 Bean 的信息
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
logger.debug("Loading bean definitions");
Element root = doc.getDocumentElement();
doRegisterBeanDefinitions(root);
}
- 首先解析 xml 里面的 profile，profile 的作用做到环境隔离
- 然后解析 root 节点；
parseDefaultElement 解析的是 Spring 自带的标签，例如：bean,import,alias,beans；而 parseCustomElement 解析是用户自定义的标签，需要用户自己去写对应的实现；
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);
}
}