用代码学习Spring：IoC、AOP

文章作者 100test 发表时间 2007:04:06 22:07:13
来源 100Test.Com百考试题网

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。






正在执行业务方法




执行业务方法前


执行业务方法后





BusinessObject.doSomething












BusinessObject



myInterceptor
myAdvisor








正在执行业务方法




执行业务方法前


执行业务方法后





BusinessObject.doSomething












BusinessObject



myInterceptor
myAdvisor






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。