關于spring 2.0自定義xml 標記 （一 主要的相關類）
在spring 2.0 中，增加了自定義xml標記這一重大的功能。下面主要看一下spring 2.0實現這一功能的主要相關類：
NamespaceHandlerResolver（接口）
由DefaultBeanDefinitionDocumentReader使用，用于定位NamespaceHandler，指定特定的命名空間uri
實現類：
DefaultNamespaceHandlerResolver
通過map 保存所有的對應關系
默認使用spring.handlers文件來保存所有的handlers
可以定義其他的location 如：
String location = "org/springframework/beans/factory/xml/support/customNamespace.properties";
NamespaceHandlerResolver resolver = new DefaultNamespaceHandlerResolver(getClass().getClassLoader(), location);
NamespaceHandler（接口）
基礎接口，用于DefaultBeanDefinitionDocumentReader處理自定義命名空間。
方法：
void init();
由DefaultBeanDefinitionDocumentReader調用在構造完后但在解析自定義元素前。
BeanDefinition parse(Element element, ParserContext parserContext);
解析指定的元素。
BeanDefinitionHolder decorate(Node element,
BeanDefinitionHolder definition,
ParserContext parserContext);
執行相應的修飾。
實現類：
NamespaceHandlerSupport（抽象類）
主要的三個方法：
protected final void registerBeanDefinitionDecorator(
String elementName,
BeanDefinitionDecorator decorator)
注冊decorator，通過element
protected final void registerBeanDefinitionDecoratorForAttribute(
String attributeName,
BeanDefinitionDecorator decorator)
注冊decorator，通過attr
protected final void registerBeanDefinitionParser(
String elementName,
BeanDefinitionParser parser)
注冊BeanDefinitionParser，通過element
實際的操作由具體的BeanDefinitionDecorator 或者BeanDefinitionParser 執行
BeanDefinitionDecorator(接口)
裝飾相關的自定義屬性。
AbstractInterceptorDrivenBeanDefinitionDecorator
用于注冊相應的Interceptor bean 定義，使用aop代理
其他類：
PluggableSchemaResolver，用于自定義相關的schema,默認的schema 保存于spring.schemas文件中
可以通過覆蓋resolveEntity方法來裝載相應的自定義xsd文件
主要的執行類：
XmlBeanDefinitionReader
用于處理相應的讀取工作，其實主要的工作委派給BeanDefinitionDocumentReader
實際的類，就介紹到這，下一節通過實例來說明如何定義自定義xml 元素
關于spring 2.0自定義xml 標記 （二 如何實現）
看了spring test 用例，其實實現這一功能還算比較簡單，主要分以下的步驟，具體的實例可以去參考spring 自帶的testcase
首先定義相關xsd文件，用于驗證相應的行為：
主要增加了4個自定義元素和1個屬性：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<xsd:schema xmlns="http://www.springframework.org/schema/beans/test"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.springframework.org/schema/beans/test"
elementFormDefault="qualified">
<xsd:element name="testBean">
<xsd:complexType>
<xsd:attribute name="id" type="xsd:string" use="required" form="unqualified"/>
<xsd:attribute name="name" type="xsd:string" use="required" form="unqualified"/>
<xsd:attribute name="age" type="xsd:integer" use="required" form="unqualified"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="set">
<xsd:complexType>
<xsd:attribute name="name" type="xsd:string" use="required" form="unqualified"/>
<xsd:attribute name="age" type="xsd:integer" use="required" form="unqualified"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="debug"/>
<xsd:element name="nop"/>
<xsd:attribute name="object-name" type="xsd:string"/>
</xsd:schema>
接著定義handler映射文件：customNamespace.properties
http\://www.springframework.org/schema/beans/test=org.springframework.beans.factory.xml.support.TestNamespaceHandler
定義Handler:
主要注冊相應的解析類和裝飾類
publicclass TestNamespaceHandler extends NamespaceHandlerSupport {
publicvoid init() {
//相對于每個xsd中定義的元素
registerBeanDefinitionParser("testBean", new TestBeanDefinitionParser());
registerBeanDefinitionDecorator("set", new PropertyModifyingBeanDefinitionDecorator());
registerBeanDefinitionDecorator("debug", new DebugBeanDefinitionDecorator());
registerBeanDefinitionDecorator("nop", new NopInterceptorBeanDefinitionDecorator());
registerBeanDefinitionDecoratorForAttribute("object-name", new ObjectNameBeanDefinitionDecorator());
}
}
定義各個解析類：
privatestaticclass TestBeanDefinitionParser implements BeanDefinitionParser {
public BeanDefinition parse(Element element, ParserContext parserContext) {
RootBeanDefinition definition = new RootBeanDefinition();
definition.setBeanClass(TestBean.class);
MutablePropertyValues mpvs = new MutablePropertyValues();
mpvs.addPropertyValue("name", element.getAttribute("name"));
mpvs.addPropertyValue("age", element.getAttribute("age"));
definition.setPropertyValues(mpvs);
parserContext.getRegistry().registerBeanDefinition(element.getAttribute("id"), definition);
returnnull;
}
}
privatestaticclassPropertyModifyingBeanDefinitionDecorator implements BeanDefinitionDecorator {
public BeanDefinitionHolder decorate(Node node, BeanDefinitionHolder definition,
ParserContext parserContext) {
Element element = (Element)node;
BeanDefinition def = definition.getBeanDefinition();
MutablePropertyValues mpvs = (def.getPropertyValues() == null) ?
new MutablePropertyValues() : def.getPropertyValues();
mpvs.addPropertyValue("name", element.getAttribute("name"));
mpvs.addPropertyValue("age", element.getAttribute("age"));
((AbstractBeanDefinition) def).setPropertyValues(mpvs);
return definition;
}
}
privatestaticclassDebugBeanDefinitionDecorator extends AbstractInterceptorDrivenBeanDefinitionDecorator {
protected BeanDefinition createInterceptorDefinition(Node node) {
returnnew RootBeanDefinition(DebugInterceptor.class);
}
}
privatestaticclassNopInterceptorBeanDefinitionDecorator extends
AbstractInterceptorDrivenBeanDefinitionDecorator {
protected BeanDefinition createInterceptorDefinition(Node node) {
returnnew RootBeanDefinition(NopInterceptor.class);
}
}
privatestaticclassObjectNameBeanDefinitionDecorator implements BeanDefinitionDecorator {
public BeanDefinitionHolder decorate(Node node, BeanDefinitionHolder definition,
ParserContext parserContext) {
Attr objectNameAttribute = (Attr)node;
definition.getBeanDefinition().setAttribute("objectName", objectNameAttribute.getValue());
return definition;
}
}
可以定義EntityResolver，用于驗證相應的xsd
privateclass DummySchemaResolver extends PluggableSchemaResolver {
public DummySchemaResolver() {
super(CustomNamespaceHandlerTests.this.getClass().getClassLoader());
}
public InputSource resolveEntity(String publicId, String systemId) throws IOException {
InputSource source = super.resolveEntity(publicId, systemId);
if (source == null) {
Resource resource =
new ClassPathResource("org/springframework/beans/factory/xml/support/spring-test.xsd");
source = new InputSource(resource.getInputStream());
source.setPublicId(publicId);
source.setSystemId(systemId);
}
return source;
}
}
關鍵的一步，如何生效：
String location = "org/springframework/beans/factory/xml/support/customNamespace.properties";
NamespaceHandlerResolver resolver = new DefaultNamespaceHandlerResolver(
getClass().getClassLoader(), location);
DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
reader.setNamespaceHandlerResolver(resolver);
reader.setValidationMode(XmlBeanDefinitionReader.VALIDATION_XSD);
reader.setEntityResolver(new DummySchemaResolver());
reader.loadBeanDefinitions(getResource());
寫一個測試xml文件：
<?xmlversion="1.0"encoding="UTF-8"?>
<beansxmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:test="http://www.springframework.org/schema/beans/test"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/beans/testhttp://www.springframework.org/schema/beans/factory/xml/support/spring-test.xsd">
<test:testBeanid="testBean"name="Rob Harrop"age="23"/>
<beanid="customisedTestBean"class="org.springframework.beans.TestBean">
<test:setname="Rob Harrop"age="23"/>
</bean>
<beanid="debuggingTestBean"class="org.springframework.beans.TestBean">
<test:debug/>
<propertyname="name"value="Rob Harrop"/>
<propertyname="age"value="23"/>
</bean>
<beanid="chainedTestBean"class="org.springframework.beans.TestBean">
<test:debug/>
<test:nop/>
<propertyname="name"value="Rob Harrop"/>
<propertyname="age"value="23"/>
</bean>
<beanid="decorateWithAttribute"class="org.springframework.beans.TestBean"test:object-name="foo"/>
</beans>
相關的測試方法：
publicvoid testSimpleParser() throws Exception {
TestBean bean = (TestBean) this.beanFactory.getBean("testBean");
assetTestBean(bean);
}
publicvoid testSimpleDecorator() throws Exception {
TestBean bean = (TestBean) this.beanFactory.getBean("customisedTestBean");
assetTestBean(bean);
}
publicvoid testProxyingDecorator() throws Exception {
ITestBean bean = (ITestBean) this.beanFactory.getBean("debuggingTestBean");
assetTestBean(bean);
assertTrue(AopUtils.isAopProxy(bean));
Advisor[] advisors = ((Advised) bean).getAdvisors();
assertEquals("Incorrect number of advisors", 1, advisors.length);
assertEquals("Incorrect advice class.", DebugInterceptor.class, advisors[0].getAdvice().getClass());
}
publicvoid testChainedDecorators() throws Exception {
ITestBean bean = (ITestBean) this.beanFactory.getBean("chainedTestBean");
assetTestBean(bean);
assertTrue(AopUtils.isAopProxy(bean));
Advisor[] advisors = ((Advised) bean).getAdvisors();
assertEquals("Incorrect number of advisors", 2, advisors.length);
assertEquals("Incorrect advice class.", DebugInterceptor.class, advisors[0].getAdvice().getClass());
assertEquals("Incorrect advice class.", NopInterceptor.class, advisors[1].getAdvice().getClass());
}
publicvoid testDecorationViaAttribute() throws Exception {
RootBeanDefinition beanDefinition
= (RootBeanDefinition)this.beanFactory.getBeanDefinition("decorateWithAttribute");
assertEquals("foo", beanDefinition.getAttribute("objectName"));
}
privatevoid assetTestBean(ITestBean bean) {
assertEquals("Invalid name", "Rob Harrop", bean.getName());
assertEquals("Invalid age", 23, bean.getAge());
}