Spring实战4 学习笔记（二）

面向切面的Spring

1、实现类：BlankDisc

package Chapter_04;

import org.springframework.stereotype.Component;
import java.util.ArrayList;
import java.util.List;

@Component("Blank")
public class BlankDisc {

    private String title = "default";
    private String artist = "ymc";
    private List tracks = new ArrayList();

    public BlankDisc() {

        tracks.add("song 1");
        tracks.add("song 2");
        tracks.add("song 3");
        tracks.add("song 4");
        tracks.add("song 5");
        tracks.add("song 6");

        tracks.add("song 7");
        tracks.add("song 8");
        tracks.add("song 9");
        tracks.add("song 10");
        tracks.add("song 11");
        tracks.add("song 12");
    }

    public void playTrack(int i)
    {
        String aa = tracks.get(i);
        System.out.println("【BlankDisc 】>>>>>>>>>>>>>>>>>Playing "+title+" by "+artist+"track:"+aa);
    }
}

2、实现类：TrackCounter，利用切面完成对不同number的track播放次数的统计

package Chapter_04;

import java.util.Map;
import java.util.HashMap;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;

@Aspect
public class TrackCounter {

    private Map trackCounts = new HashMap();

    @Pointcut(
            "execution(* Chapter_04.BlankDisc.playTrack(int)) "+
            "&& args(trackNumber1)")
    public void trackPlayed(int trackNumber1){}

    @Before("trackPlayed(trackNumber1)")
    public void countTrack(int trackNumber1){
        int currentCount = getPlayCount(trackNumber1);
        trackCounts.put(trackNumber1,currentCount+1);
    }

    public int getPlayCount(int trackNumber)
    {
        return  trackCounts.containsKey(trackNumber)?trackCounts.get(trackNumber):0;
    }
}

3、配置类：

package Chapter_04;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

@Configuration
@EnableAspectJAutoProxy
public class TrackCounterConfig {

    @Bean
    public  BlankDisc getBlankDisc()
    {
        BlankDisc cd = new BlankDisc();
        return  cd;
    }

    @Bean
    public TrackCounter trackCounter()
    {
        return new TrackCounter();
    }
}

4、测试类，调用playTrack方法，来通知切面对播放进行计数，最后打印number为2的track的播放次数：

package Chapter_04;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = TrackCounterConfig.class)
public class TrackCounterTest {

    @Autowired
    private  BlankDisc cd;

    @Autowired
    private  TrackCounter counter;

    @Test
    public void testTrackCounter(){

        System.out.println("112333");
        cd.playTrack(1);
        cd.playTrack(2);
        cd.playTrack(2);
        cd.playTrack(3);
        cd.playTrack(4);


        System.out.println("song 2的播放次数："+counter.getPlayCount(2));
    }
}

5、执行结果：

112333
【BlankDisc 】>>>>>>>>>>>>>>>>>Playing default by ymctrack:song 2
【BlankDisc 】>>>>>>>>>>>>>>>>>Playing default by ymctrack:song 3
【BlankDisc 】>>>>>>>>>>>>>>>>>Playing default by ymctrack:song 3
【BlankDisc 】>>>>>>>>>>>>>>>>>Playing default by ymctrack:song 4
【BlankDisc 】>>>>>>>>>>>>>>>>>Playing default by ymctrack:song 5
song 2的播放次数：2