spring2自定义标签

本文javaeye同步更新地址：

http://lcllcl987.iteye.com/blog/351655

spring2以上版本支持自定义标签.
作为一般的应用程序开发人员，扩展spring的标签意义不大。

但如果你是一个平台开发人员，则很有必要拥有一套自己的标签, 提供给应用开发人员使用.
由于mule的标签是基于spring的xml schema扩展的, 为了弄出mule的自定义标签， 今天研究了一下spring的标签扩展, 并笔记之
让我们从一个简单的spring标签制作开始吧。
我需要做的标签如下：
<co:log id="iplatformLog" isPrintTime="true" company="cyber" />
这个标签功能简单， 仅仅打印一下log.它和如下spring bean功能一样：
<bean id="log" class="co.iplatform.log.LogBean"> <constructor-arg value="true"></constructor-arg> <property name="company" value="cyber"></property> </bean>

标签的schema如下：
<?xml version="1.0" encoding="UTF-8"?> <xsd:schema xmlns="http://www.springframework.org/schema/myns" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:beans="http://www.springframework.org/schema/beans" targetNamespace="http://www.mycompany.com/schema/myns" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xsd:import namespace="http://www.springframework.org/schema/beans"/> <xsd:element name="log"> <xsd:complexType> <xsd:complexContent> <xsd:extension base="beans:identifiedType"> <xsd:attribute name="isPrintTime" type="xsd:boolean" use="required"/> <xsd:attribute name="company" type="xsd:string"/> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> </xsd:schema>

log标签背后的bean如下：
public class LogBean { private boolean isPrintTiem = false; private String company = ""; public LogBean(boolean isPrintTime) { this.isPrintTiem = isPrintTime; } public void print(String log) { if(this.isPrintTiem) System.out.println(this.company + new Date() + ":" + log); else System.out.println(this.company + ":" + log); } public String getCompany() { return company; } public void setCompany(String company) { this.company = company; } public boolean isPrintTiem() { return isPrintTiem; } }

实现一个标签需要扩展一个class：
NamespaceHandlerSupport

并实现一个interface：

BeanDefinitionParser public class LogNamespaceHandler extends NamespaceHandlerSupport { public void init() { registerBeanDefinitionParser("log", new LogBeanDefinitionParser()); } }
LogNamespaceHandler在spring的Ioc容器加载配置文件时，遇到log节点便会调用LogBeanDefinitionParser，完成bean的初始化，并注册到spring context中.
public class LogBeanDefinitionParser implements BeanDefinitionParser { public BeanDefinition parse(Element element, ParserContext parserContext) { // create a RootBeanDefinition that will serve as configuration // holder for the 'pattern' attribute and the 'lenient' attribute RootBeanDefinition beanDef = new RootBeanDefinition(); beanDef.setBeanClass(LogBean.class); // never null since the schema requires it String pattern = element.getAttribute("isPrintTime"); beanDef.getConstructorArgumentValues().addGenericArgumentValue(pattern); String company = element.getAttribute("company"); if(StringUtils.hasText(company)) { beanDef.getPropertyValues().addPropertyValue("company",company); } // retrieve the ID attribute that will serve as the bean identifier in // the context String id = element.getAttribute("id"); // create a bean definition holder to be able to register the // bean definition with the bean definition registry // (obtained through the ParserContext) BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDef, id); // register the BeanDefinitionHolder (which contains the bean // definition) // with the BeanDefinitionRegistry BeanDefinitionReaderUtils.registerBeanDefinition(holder, parserContext .getRegistry()); return beanDef; } }
最后在META_INF中， 加入两个配置文件：
spring.handlers和spring.schemas
spring.handlers内容如下：
http\://www.mycompany.com/schema/myns=co.iplatform.log.LogNamespaceHandler spring.schemas内容如下： http\://www.mycompany.com/schema/myns/myns.xsd=co/iplatform/log/logns.xsd

最后测试一下：
新建一个applicationContext.xml：
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:co="http://www.mycompany.com/schema/myns" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.mycompany.com/schema/myns http://www.mycompany.com/schema/myns/myns.xsd "> <co:log id="iplatformLog" isPrintTime="true" company="cyberObject" /> <bean id="log" class="co.iplatform.log.LogBean"> <constructor-arg value="true"></constructor-arg> <property name="company" value="cyberObject"></property> </bean> </beans>

testcase：
public class LogTagTest extends AbstractDependencyInjectionSpringContextTests { protected String[] getConfigLocations() { return new String[] {"classpath*:applicationContext*.xml"}; } public void testLogBean() { LogBean logBean = (LogBean)this.applicationContext.getBean("iplatformLog"); assertTrue(StringUtils.hasText(logBean.getCompany())); assertTrue(logBean.isPrintTiem()); logBean.print("is fun!"); } }

绿色在期待中出现.

为了让mule使用这个bean， 只需mule的配置文件导入上面的spring的Application.xml

<spring:beans> <spring:import resource="applicationContext.xml" /> </spring:beans>

然后定义一个mule：
<model name="LogModel"> <service name="databaseCommonUMO"> <!-- any number of endpoints can be added to an inbound router --> <inbound> <vm:inbound-endpoint path="logQueue" /> </inbound> <component> <method-entry-point-resolver> <include-entry-point method="print" /> </method-entry-point-resolver> <spring-object bean="iplatformLog"></spring-object> </component> </service> </model> </mule>

写一个mule的测试：
public class MySpringTagMuleClientTest { public static void main(String[] args) throws MuleException { // create mule MuleContext muleContext; String config = "mule-myspringtag-config.xml"; muleContext = new DefaultMuleContextFactory().createMuleContext(config); muleContext.start(); // creat mule client MuleClient client = new MuleClient(); MuleMessage response = client.send("vm://logQueue", "hello, I'm log content.", null); } }