Swing運用：音樂播放器

16×16的樂器組合，可勾選不同組合播放樂音，
勾選后按下start鍵即可回圈播放，按下stop鍵即可停止；

package a新音樂播放器;

import javax.sound.midi.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.util.ArrayList;

public class BeatBox {
    JPanel mainPanel;
    //把checkbox存盤在ArrayList中
    ArrayList<JCheckBox> checkboxList;

    Sequencer sequencer;
    Sequence sequence;
    Track track;
    JFrame theFrame;
    //設定樂器名稱
    String [] instrumentNames = {"Bass Drum","Closed Hi-Hat","Open Hi-Hat","Acoustic Snare","Crash Cymbal","Hand Clap","High Tom","Hi Bongo","Maracas","Whistle","Low Conga","Cowbell","Vibraslap","Low-mid Tom","High Agogo","Open Hi Conga"};
    //樂器在Java中對應的關鍵字
    int[] instruments = {35,42,46,38,49,39,50,60,70,72,64,56,58,47,67,63};
    //main（）函式
    public static void main(String[] args) {
        new BeatBox().buildGUI();
    }
    //創建GUI
    public  void buildGUI()
    {
        theFrame = new JFrame("Cyber BeatBox");
        theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //背景
        BorderLayout layout = new BorderLayout();
        JPanel background = new JPanel(layout);
        //設定面板上擺設組件的空白邊緣
        background.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));

        checkboxList = new ArrayList<JCheckBox>();
        Box buttonBox = new Box(BoxLayout.Y_AXIS);//用BoxLayout進行布局

        //start按鈕，開始回圈播放
        JButton start = new JButton("Start");
        start.addActionListener(new MyStartListener());
        buttonBox.add(start);

        //stop按鈕，停止播放
        JButton stop = new JButton("Stop");
        stop.addActionListener(new MyStopListener());
        buttonBox.add(stop);

        //調高節奏
        JButton upTempo = new JButton("Tempo Up");
        stop.addActionListener(new MyUpTempoListener());
        buttonBox.add(upTempo);

        //調低節奏
        JButton downTempo = new JButton("Tempo Down");
        downTempo.addActionListener(new MyDownTempoListener());
        buttonBox.add(downTempo);

        //將樂器名字按照BoxLayout進行排列
        Box nameBox = new Box(BoxLayout.Y_AXIS);
        for(int i=0;i<16;i++)
        {
            nameBox.add(new Label(instrumentNames[i]));
        }

        //將4個按鈕設定在背景的右邊，將樂器名字設定在左邊
        background.add(BorderLayout.EAST,buttonBox);
        background.add(BorderLayout.WEST,nameBox);

        //把設定好的背景添加到JFrame物件中
        theFrame.getContentPane().add(background);

        //按GridLayout的排列方式設定16*16的格子
        GridLayout grid = new GridLayout(16,16);
        grid.setVgap(1);//設定垂直間距
        grid.setHgap(2);//設定水平間距
        //將16*16的勾選格加到背景中
        mainPanel = new JPanel(grid);
        background.add(BorderLayout.CENTER,mainPanel);

        //創建checkbox組，設定未勾選的為false并加到ArrayList和面板上
        for(int i=0;i<256;i++)
        {
            JCheckBox c = new JCheckBox();
            c.setSelected(false);
            checkboxList.add(c);
            mainPanel.add(c);
        }

        setUpMidi();

        //基操
        theFrame.setBounds(50,50,300,300);
        theFrame.pack();
        theFrame.setVisible(true);
    }

    //setUPMidi（）方法是一般的Midi設定程式代碼
    public void setUpMidi()
    {
        try{
            sequencer = MidiSystem.getSequencer();
            sequencer.open();
            sequence = new Sequence(Sequence.PPQ,4);
            track = sequence.createTrack();
            sequencer.setTempoInBPM(120);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    //開始播放的方法
    public void buildTrackAndStart(){
        int[] trackList =null;//儲存樂器值

        //消掉舊的track并創建一個新的
        sequence.deleteTrack(track);
        track = sequence.createTrack();

        //對16個樂器都執行一遍
        for(int i=0;i<16;i++)
        {
            trackList = new int[16];

            int key = instruments[i];//樂器關鍵字

            //對每一拍都執行一次
            for(int j=0;j<16;j++)
            {
                //以列為單位逐個遍歷
                JCheckBox jc = (JCheckBox) checkboxList.get(j+(16*i));
                //如果勾選了，就加到陣列中，否則補0
                if(jc.isSelected()){
                    trackList[j] = key;
                }else{
                    trackList[j] = 0;
                }

            }
            //創建樂器事件并加到track中
            makeTracks(trackList);
            track.add(makeEvent(176,1,127,0,16));
        }

        //確保第16拍有事件，從而實作回圈播放
        track.add(makeEvent(192,9,1,0,15));
        try{
            sequencer.setSequence(sequence);
            sequencer.setLoopCount(sequencer.LOOP_CONTINUOUSLY);//指定為無窮次數
            sequencer.start();//開始播放
            sequencer.setTempoInBPM(120);
        }catch (Exception e){
            e.printStackTrace();
        }
    }
    
    //四個內部類，分別實作4個按鈕的接聽
    public class MyStartListener implements ActionListener{
        public void actionPerformed(ActionEvent a){
            buildTrackAndStart();
        }
    }
    public class MyStopListener implements ActionListener{
        public void actionPerformed(ActionEvent a){
            sequencer.stop();
        }
    }
    public class MyUpTempoListener implements ActionListener{
        public void actionPerformed(ActionEvent a){
            float tempoFactor = sequencer.getTempoFactor();
            sequencer.setTempoFactor((float)(tempoFactor* 1.03));
        }
    }
    public class MyDownTempoListener implements ActionListener{
        public void actionPerformed(ActionEvent a){
            float tempoFactor = sequencer.getTempoFactor();
            sequencer.setTempoFactor((float)(tempoFactor* .97));
        }
    }
    
    public  void makeTracks(int[] list)
    {
        for(int i=0;i<16;i++)
        {
            int key = list[i];
            if(key !=0)
            {
                track.add(makeEvent(144,9,key,100,i));
                track.add(makeEvent(128,9,key,100,i+1));
            }
        }
    }
    //1-4個引數是給資訊用的，tick是何時播放資訊
    public MidiEvent makeEvent(int comd,int chan,int one,int two,int tick){
        MidiEvent event = null;
        try{
            ShortMessage a = new ShortMessage();
            a.setMessage(comd,chan,one,two);
            event = new MidiEvent(a,tick);
        }catch (Exception e){
            e.printStackTrace();
        }
        //回傳事件
        return event;
    }
    public class MyReadInListener implements ActionListener{
        public void actionPerformed(ActionEvent a){
            boolean[] checkboxState = null;
            try{
                FileInputStream fileIn = new FileInputStream(new File("Checkbox.ser"));
                ObjectInputStream is =new ObjectInputStream(fileIn);
                checkboxState = (boolean[])is.readObject();
            }catch (Exception e){
                e.printStackTrace();
            }
            for(int i=0;i<256;i++)
            {
                JCheckBox check = (JCheckBox) checkboxList.get(i);
                if(checkboxState[i]){
                    check.setSelected(true);
                }else{
                    check.setSelected(false);
                }
            }
            sequencer.stop();
            buildTrackAndStart();
        }
    }


}