本文介绍了详解spring切面使用传递给被通知方法的参数，分享给大家，具体如下：
场景：
blankdisc代表cd实体，可以通过playtrack()方法直接播放某一个磁道中的歌曲。
需求是记录每个磁道被播放的次数。
一种方法就是修改playtrack()方法，直接在每次调用的时候记录这个数量。但是，记录磁道的播放次数与播放本身是不同的关注点，因此不应该属于playtrack()方法。这应该是切面要完成的任务。
compactdisc接口
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public interface compactdisc {
//播放某一个磁道中的歌曲
void playtrack(string track);
}
实现类blankdisc
public class blankdisc implements compactdisc {
private string title;
private string artist;
private list<string> tracks;
public void settitle(string title) {
this.title = title;
}
public void setartist(string artist) {
this.artist = artist;
}
public void settracks(list<string> tracks) {
this.tracks = tracks;
}
@override
public void playtrack(string track) {
system.out.println("-track: " + track);
}
}
切面类tracecount
/**
* 切面类的任务：记录每个磁道被播放的次数
* created by administrator on 2017/12/1.
*/
@component
@aspect
public class trackcounter {
private map<string, integer> trackcounts = new hashmap<>();
@pointcut("execution(* chapter04.aop_args.blankdisc.playtrack(string)) && args(track)")
public void trackplayed(string track) {
}
//在播放前，为该磁道计数
@before("trackplayed(track)")
public void counttrack(string track) {
int currentcount = getplaycount(track);
trackcounts.put(track, currentcount + 1);
}
public int getplaycount(string track) {
return trackcounts.containskey(track) ? trackcounts.get(track) : 0;
}
}
applicationcontext.xml配置文件
<context:component-scan base-package="aop_test,chapter04"/>
<bean id="compactdisc"
class="chapter04.aop_args.blankdisc">
<property name="title" value="sgt. pepper's lonely hearts club band" />
<property name="artist" value="the beatles" />
<property name="tracks">
<list>
<value>sgt. pepper's lonely hearts club band</value>
<value>with a little help from my friends</value>
<value>lucy in the sky with diamonds</value>
<value>getting better</value>
<value>fixing a hole</value>
<value>she's leaving home</value>
<value>being for the benefit of mr. kite!</value>
<value>within you without you</value>
<value>when i'm sixty-four</value>
<value>lovely rita</value>
<value>good morning good morning</value>
<value>sgt. pepper's lonely hearts club band (reprise)</value>
<value>a day in the life</value>
</list>
</property>
</bean>
<!-- 开启aop注解 -->
<aop:aspectj-autoproxy/>
测试
@runwith(springjunit4classrunner.class)
@contextconfiguration("classpath:applicationcontext.xml")
public class test_aop_args {
@autowired
compactdisc cd;
@autowired
trackcounter trackcounter;
@test
public void test(){
cd.playtrack("sgt. pepper's lonely hearts club band");
cd.playtrack("with a little help from my friends");
cd.playtrack("lucy in the sky with diamonds");
cd.playtrack("sgt. pepper's lonely hearts club band");
cd.playtrack("with a little help from my friends");
cd.playtrack("sgt. pepper's lonely hearts club band");
system.out.println(trackcounter.getplaycount("sgt. pepper's lonely hearts club band"));
system.out.println(trackcounter.getplaycount("with a little help from my friends"));
system.out.println(trackcounter.getplaycount("lucy in the sky with diamonds"));
system.out.println(trackcounter.getplaycount("getting better"));
}
}
测试结果 3，2，1，0
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