Head_First_Java之BeatBox.java

import javax.swing.*;
import java.awt.*;
import javax.sound.midi.*;
import java.util.*;//ArrayList
import java.awt.event.*;

public class BeatBox {
JPanel mainPanel;
ArrayList checkboxList;//把checkbox存储在ArrayList中
Sequencer sequencer;
Sequence sequence;
Track track;
JFrame theFrame;

String[] instrumentNames={"Bass Drum","Close Hi-Hat","Open Hi-Hat","Acounstic snare","Crash Cymbal","Hand Clap",
"High Tom","Hi Bongo","Maracas","Whistle","Low conga","Cowbell","Vibraslap","Low-mid Tom","High Agogo","Open Hi Conga"};
//乐器的名称，以String的array维护
int[] instruments={35,42,46,38,49,39,50,60,70,72,64,56,58,47,67,63};
//实际的乐器关键字，例如说35就代表Bass Drum

public static void main(String[] args){
BeatBox beatBox=new BeatBox();
beatBox.buildGUI();
}

public void buildGUI(){
theFrame=new JFrame("Cyber BeatBox");
theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel background=new JPanel(new BorderLayout());//JPanel面板需要添加BorderLayout布局管理器
background.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));//设置面板上摆设组件时的空白边缘

checkboxList=new ArrayList();
Box buttonBox=new Box(BoxLayout.Y_AXIS);

JButton start =new JButton("Start");
start.addActionListener(new MyStartListener());
buttonBox.add(start);

JButton stop =new JButton("Stop");
stop.addActionListener(new MyStopListener());
buttonBox.add(stop);

JButton upTempo=new JButton("Tempo Up");
upTempo.addActionListener(new MyUpTempoListener());
buttonBox.add(upTempo);

JButton downTempo=new JButton("Tempo Down");
downTempo.addActionListener(new MyDownTempoListener());
buttonBox.add(downTempo);

Box nameBox=new Box(BoxLayout.Y_AXIS);
for(int i=0;i<16;i++){
nameBox.add(new Label(instrumentNames[i]));
}

background.add(BorderLayout.EAST,buttonBox);
background.add(BorderLayout.WEST,nameBox);

GridLayout grid=new GridLayout(16,16);//布局管理器之网格布局GridLayout (16*16的网格分布）
grid.setVgap(1);//设置垂直间距
grid.setHgap(5);//设置水平间距
mainPanel=new JPanel(grid);
background.add(BorderLayout.CENTER,mainPanel);

for(int i=0;i<256;i++){
JCheckBox c=new JCheckBox();
c.setSelected(false);
checkboxList.add(c);
mainPanel.add(c);          //从左至右，从上至下
}
setUpMidi();

theFrame.getContentPane().add(background);
//theFrame.setBounds(50,50,100,100);
theFrame.pack();//若是已定义的setBound()范围太小，窗口自动调整
theFrame.setVisible(true);
}

public void setUpMidi(){  //midi音频
try{
sequencer=MidiSystem.getSequencer();
sequencer.open();
sequence=new Sequence(Sequence.PPQ,4);
track=sequence.createTrack();
sequencer.setTempoInBPM(120);
}catch(Exception e){e.printStackTrace();}
}

public void buildTrackAndStart(){
int[] trackList=null;

sequence.deleteTrack(track);
track=sequence.createTrack();//清除旧的track，重建一个新的

for(int i=0;i<16;i++){
trackList=new int[16];

int key=instruments[i];  //设定代表乐器的关键字

for(int j=0;j<16;j++){

JCheckBox jc=(JCheckBox) checkboxList.get(j+(16*i));
if(jc.isSelected()){   //判断选取的状态
trackList[j]=key;
}else{
trackList[j]=0;
}
}

makeTracks(trackList);
//track.add(makeEvent(176,1,127,0,16));//不会做任何事情，只是让我们知道有音符在播放
}

track.add(makeEvent(192,9,1,0,15));//确拍保第16拍有事件，否则BeatBox不会重复播放
try{
sequencer.setSequence(sequence);
sequencer.setLoopCount(sequencer.LOOP_CONTINUOUSLY);//指定无穷的重复次数
sequencer.start();
sequencer.setTempoInBPM(120);
}catch(Exception e){e.printStackTrace();}
}

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=se
81b1
quencer.getTempoFactor();
sequencer.setTempoFactor((float)(tempoFactor*2));//节奏速度
}
}
public class MyDownTempoListener implements ActionListener{
public void actionPerformed(ActionEvent a){
float tempoFactor=sequencer.getTempoFactor();
sequencer.setTempoFactor((float)(tempoFactor*0.5));
}
}

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));
}
}
}

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);//tick表示拍
}catch(Exception e){e.printStackTrace();}
return event;
}

}