记第一次AOP配置成功

AOP 即面向切面编程我现在的理解是让对象将关注点仅放在自身所注重上无视无关自己的事物
就比如说我播放器正在放歌我播放器播放歌的时候并不需要关注这歌一共播放了多少遍只需要关注放歌这个事件就可以了

文件结构

下面就来一一说明各个文件内容

接口 CompactDisc 
public interface CompactDisc {
    void playTrack(int k);
}

用于实现CompactDisc接口的BlankDisc类
import java.util.List;
public class BlankDisc  implements CompactDisc{
    String title;
    String artist;
    List<String> tracks;
    void setTitle(String title){
        this.title = title;
    }
    void setArtist(String artist){
        this.artist = artist;
    }
    void setTracks(List<String> tracks){
        this.tracks = tracks;
    }
    public void playTrack(int k){ //用来播放cd上顺序k的歌曲
        System.out.println(tracks.get(k));
    }
}

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

@Aspect//申明切面
public class TrackCounter {
    private Map<Integer,Integer> trackCounters = new HashMap<Integer,Integer>();
    @Pointcut( //切点 这样写之后需要每次在位置申明之后加上下面的函数就可以了
            "execution(* CompactDisc.playTrack(int) )"+
                    "&& args(trackNumber) ")
    public void trackPlayer(int trackNumber) { }
     @Before("trackPlayer(trackNumber)")  //Advice 切面该怎么做 这里是记录每首歌播放了几次
    public void countTrack(int trackNumber){
        int currentCount = getPlayCount(trackNumber);
        trackCounters.put(trackNumber,currentCount+1);
        System.out.println("歌曲"+trackNumber+"已播放"+(currentCount+1)+"遍");
    }
    public int getPlayCount(int trackNumber){
        return trackCounters.containsKey(trackNumber)?trackCounters.get(trackNumber):0;
    }
}

用java配置
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

import java.util.ArrayList;
import java.util.List;

@Configuration//配置申明
@EnableAspectJAutoProxy //自动配置切面申明
public class TrackCountConfig {
    @Bean
    public CompactDisc seggPeppers(){
        BlankDisc cd = new BlankDisc();
        cd.setTitle("歌名");
        cd.setArtist("歌手");
        List<String> tracks = new ArrayList<String> ();
        tracks.add("歌曲1");
        tracks.add("歌曲2");
        tracks.add("歌曲3");
        tracks.add("歌曲4");
        cd.setTracks(tracks);

        return cd;
    }

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

Test类
import org.junit.Rule;
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;


import static org.junit.Assert.*;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes=TrackCountConfig.class)
public class BlankDiscTest {

    @Autowired
    private CompactDisc cd;

    @Autowired
    private TrackCounter counter;

    @org.junit.Test
    public void testTrackCounter() {
        cd.playTrack(1);
        cd.playTrack(2);
        cd.playTrack(3);

    }
}

需要注意的是如果要使用AOP 需要加载三个库文件
分别是 aspectj-1.8.13.jar aspectjrt.jar aspectj-weaver.jar

结果图

代码都在我的github上~