| 用代码学习Spring：IoC、AOP |
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Damastes 原创 更新：2006-12-10 12:27:26 版本: 1.0
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1 从http://www.springframework.org下载Spring
2 用eclipse新建Java项目
3 建立我们的业务方法接口
public interface BusinessObject {
public void doSomething();
public void doAnotherThing();
}
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;public interface BusinessObject {
public void doSomething();
public void doAnotherThing();
}
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
4 实现业务方法，注意这是的setWords使用了依赖注入，所谓依赖注入就是把配置文件中的字符串什么的在程序运行时“自动”放到我们的程序中来。如果不是这样，我们就只能在代码中固化这些东西，从而违背了面向对象的依赖倒置原则，还有一种满足依赖倒置的方法，即依赖查询，这就是所谓的factory模式，即在代码中请求某种抽象的东西，然后根据配置得到它，但这种办法向对于依赖注入多了对环境的依赖，且代码冗余，EJB的JNDI查询就属于这种。另外我们的Spring配置文件是以bean为核心的，就是我们写的一个类，在XML中描述它的名称、位置和涵盖的内容、关系。
public class BusinessObjectImpl implements BusinessObject {
private String words;
public void setWords(String words){
this.words = words;
}
public void doSomething() {
Log log = LogFactory.getLog(this.getClass());
log.info(words);
}
public void doAnotherThing() {
Log log = LogFactory.getLog(this.getClass());
log.info("Another thing");
}
}public class BusinessObjectImpl implements BusinessObject {
private String words;
public void setWords(String words){
this.words = words;
}
public void doSomething() {
Log log = LogFactory.getLog(this.getClass());
log.info(words);
}
public void doAnotherThing() {
Log log = LogFactory.getLog(this.getClass());
log.info("Another thing");
}
}
5 建立一个运行方法类，从配置文件spring-beans.xml中读入bo这个类的定义，然后实例化一个对象
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
public class Main {
public static void main(String[] args){
XmlBeanFactory xbf = new XmlBeanFactory(new ClassPathResource("spring-beans.xml"));
BusinessObject bo = (BusinessObject)xbf.getBean("bo");
bo.doSomething();
bo.doAnotherThing();
}
}import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
public class Main {
public static void main(String[] args){
XmlBeanFactory xbf = new XmlBeanFactory(new ClassPathResource("spring-beans.xml"));
BusinessObject bo = (BusinessObject)xbf.getBean("bo");
bo.doSomething();
bo.doAnotherThing();
}
}
6 建立一个拦截器类invoke是MethodInterceptor必须实现的方法，表示拦截时的动作，大家仔细体会代码中的含义
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class MyInterceptor implements MethodInterceptor {
private String before, after;
public void setAfter(String after) {
this.after = after;
}
public void setBefore(String before) {
this.before = before;
}
public Object invoke(MethodInvocation invocation) throws Throwable {
Log log = LogFactory.getLog(this.getClass());
log.info(before);
Object rval = invocation.proceed();
log.info(after);
return rval;
}
}import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class MyInterceptor implements MethodInterceptor {
private String before, after;
public void setAfter(String after) {
this.after = after;
}
public void setBefore(String before) {
this.before = before;
}
public Object invoke(MethodInvocation invocation) throws Throwable {
Log log = LogFactory.getLog(this.getClass());
log.info(before);
Object rval = invocation.proceed();
log.info(after);
return rval;
}
}
7 建立配置文件组织上面的类之间的关系，AOP有切入点和增强这两个重要的概念，把两个概念结合到一起，就是一个在某个方法执行的时候附加执行，切入点表示在哪里附加，增强表示附加什么，配置文件中的myPointcut表示切入点，myInterceptor表示增强的内容，myAdvisor表示增强器，即两者的结合，在bo这个bean中，我们把这个增强器附加到了bo这个bean上。
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="businessObjectImpl" class="BusinessObjectImpl">
<property name="words">
<value>正在执行业务方法</value>
</property>
</bean>
<bean id="myInterceptor" class="MyInterceptor">
<property name="before">
<value>执行业务方法前</value>
</property>
<property name="after">
<value>执行业务方法后</value>
</property>
</bean>
<bean id="myPointcut" class="org.springframework.aop.support.JdkRegexpMethodPointcut">
<property name="patterns">
<list>
<value>BusinessObject.doSomething</value>
</list>
</property>
</bean>
<bean id="myAdvisor" class="org.springframework.aop.support.DefaultPointcutAdvisor">
<property name="pointcut" ref="myPointcut"/>
<property name="advice" ref="myInterceptor"/>
</bean>
<bean id="bo" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="target">
<ref local="businessObjectImpl"/>
</property>
<property name="proxyInterfaces">
<value>BusinessObject</value>
</property>
<property name="interceptorNames">
<list>
<value>myInterceptor</value>
<value>myAdvisor</value>
</list>
</property>
</bean>
</beans><?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="businessObjectImpl" class="BusinessObjectImpl">
<property name="words">
<value>正在执行业务方法</value>
</property>
</bean>
<bean id="myInterceptor" class="MyInterceptor">
<property name="before">
<value>执行业务方法前</value>
</property>
<property name="after">
<value>执行业务方法后</value>
</property>
</bean>
<bean id="myPointcut" class="org.springframework.aop.support.JdkRegexpMethodPointcut">
<property name="patterns">
<list>
<value>BusinessObject.doSomething</value>
</list>
</property>
</bean>
<bean id="myAdvisor" class="org.springframework.aop.support.DefaultPointcutAdvisor">
<property name="pointcut" ref="myPointcut"/>
<property name="advice" ref="myInterceptor"/>
</bean>
<bean id="bo" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="target">
<ref local="businessObjectImpl"/>
</property>
<property name="proxyInterfaces">
<value>BusinessObject</value>
</property>
<property name="interceptorNames">
<list>
<value>myInterceptor</value>
<value>myAdvisor</value>
</list>
</property>
</bean>
</beans>
8 运行Main类，观察控制台输出结果，重新审查代码，反思为什么会出现这种结果。
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评论人：zifeng_java
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发表时间: Wed Dec 13 10:11:33 CST 2006
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正式学习中。
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评论人：xzcgeorge
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发表时间: Fri Dec 15 10:26:23 CST 2006
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