Applet实例 ——实时曲线

import java.applet.Applet; import java.awt.Color; import java.awt.Graphics; import java.awt.Image; import java.sql.*; import java.util.*; import javax.swing.JOptionPane; public class Carve extends Applet { /** * */ private static final long serialVersionUID = 1L; List<Points> MyList = new ArrayList<Points>(); List<Points> MyList_copy = new ArrayList<Points>(); Image offScreenImage = null; public static boolean Live = true; //用来控制CanveThread ，灵活控制是否画曲线 public static boolean cycle=true; //用来控制查看历史的时候点的读取 String str; UUID uuid; Thread th; LinkToDB link = new LinkToDB(); public void paint(Graphics g){ Points p = new Points(); Points point2; uuid=UUID.randomUUID(); p.setX(0); p.setY(new Random().nextInt(250)); str = "insert into Point (Point_Id,Point_X,Point_Y) values('"+uuid+"',"+p.getX()+","+p.getY()+")"; try { link.stt = link.con.createStatement(); link.stt.executeUpdate(str); } catch (SQLException e) { JOptionPane.showMessageDialog(null, e.getMessage()); } MyList_copy.add(p); MyList.add(p); Color c = g.getColor(); for(int i=0;i<MyList.size();i++) //遍历整个ArrayList，读出里面所有的Points { if(MyList.size()==1){ //只有一个点时 Points point1 = MyList.get(0); g.setColor(Color.RED); g.drawLine(point1.getX(),point1.getY(),point1.getX(),point1.getY()); g.setColor(c); } else{ Points point1 = MyList.get(i); if(i+1>=MyList.size()){ //画到MyList的最后一个点时 point2 =point1; g.setColor(Color.RED); g.drawLine(point1.getX(),point1.getY(),point2.getX(),point2.getY()); g.setColor(c); }else{ point2 = MyList.get(i+1); g.setColor(Color.RED); g.drawLine(point1.getX(),point1.getY(),point2.getX(),point2.getY()); g.setColor(c); } } } for(int i=0;i<MyList.size();i++){ //实现曲线往前走 MyList.get(i).setX(MyList.get(i).getX()+20); } if(MyList.size()>30){ //优化，如果MyList中的points大于Applet能显示的范围，则去掉不能显示在Applet中的Points for(int i=0;i<MyList.size()-30;i++){ MyList.remove(i); } } //只留下30个点，只要能够在Applet的显示范围显示就行 } public void update(Graphics g) { //画纸 if(offScreenImage == null) { offScreenImage = this.createImage(500, 300); } Graphics gOffScreen = offScreenImage.getGraphics(); Color c = gOffScreen.getColor(); gOffScreen.setColor(Color.ORANGE); gOffScreen.fillRect(0, 0, 500, 300); gOffScreen.setColor(c); paint(gOffScreen); g.drawImage(offScreenImage, 0, 0, null); } private class carveThread implements Runnable{ public void run() { while(Live){ repaint(); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } } public void init() { this.setBackground(Color.YELLOW); th=new Thread(new carveThread()); th.start(); // this.history(); } /** * 点类 * @author Administrator * */ private class Points { private int X; private int Y; public int getX() { return X; } public void setX(int x) { X = x; } public int getY() { return Y; } public void setY(int y) { Y = y; } public Points(){} public Points(int x,int y){ this.X =x; this.Y =y; } } /* * 连接数据库 */ private class LinkToDB { public Statement stt; //声明一个Statement对象 public ResultSet rs; //声明一个ResultSet对象 public Connection con; LinkToDB(){ String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver"; String linkName="jdbc:sqlserver://localhost:1433; Database=Points;user=sa;password=1234"; try { Class.forName(driver); con=DriverManager.getConnection(linkName); //建立连接 stt=con.createStatement(); //创建Statement } catch (Exception e) { e.printStackTrace(); // link.con.close(); } } } public void change(){ //线程暂停 Live = false; cycle = false; } public void continue1(){ //线程继续 cycle = false; Live = true; if(th.getState()==Thread.State.TIMED_WAITING){ //如果线程处于运行状态下（程序还在画曲线），就什么都不做 } else{ th=new Thread(new carveThread()); th.start(); //否则，重新接着画曲线 } } /** * 可能history里面往前走的没加对，修改之 */ public void history(){ //查看历史记录方法 Live = false; cycle=true; Points t; int j=1,h=1,l=0; //j用来帮助实现第一次画一个，第二次画两个.....，h用来帮助实现当画完整个MyList_copy2的时候退出循环，l用来记录当前所画的点下标 List<Points> MyList_copy2 = new ArrayList<Points>(); // for(int i=0;i<MyList_copy.size();i++){ // MyList_copy2.add(MyList_copy.get(i)); // } //复制MyList_copy的内容到Mylist_copy2 String str1 = "select Point_Y from Point"; try { link.stt = link.con.createStatement(); link.rs = link.stt.executeQuery(str1); while(link.rs.next()){ t = new Points(); t.setY(link.rs.getInt("Point_Y")); t.setX(0); MyList_copy2.add(t); } } catch (SQLException e1) { JOptionPane.showMessageDialog(null, e1.getMessage()); } // for(int m=0;m<MyList_copy2.size();m++){ // MyList_copy2.get(m).setX(0); // } Graphics g1 = this.getGraphics(); g1.clearRect(0, 0, 500, 300); //把屏幕先清空 Color c = g1.getColor(); while(cycle){ for(int k=0;k<MyList_copy2.size();k++){ j--; if(j==0){ l=k; break; } if(MyList_copy2.size()==1||k==0) { g1.setColor(Color.BLUE); //只有一个点或k=0的情况下 g1.drawLine(MyList_copy2.get(0).getX(), MyList_copy2.get(0).getY(), MyList_copy2.get(0).getX(), MyList_copy2.get(0).getY()); g1.setColor(c); }else if((k+1)==MyList.size()) { g1.setColor(Color.BLUE); g1.drawLine(MyList_copy2.get(k).getX(), MyList_copy2.get(k).getY(), MyList_copy2.get(k).getX(), MyList_copy2.get(k).getY()); g1.setColor(c); }else { g1.setColor(Color.BLUE); g1.drawLine(MyList_copy2.get(k-1).getX(), MyList_copy2.get(k-1).getY(), MyList_copy2.get(k).getX(), MyList_copy2.get(k).getY()); g1.setColor(c); } } for(int n=0;n<l;n++){ MyList_copy2.get(n).setX(MyList_copy2.get(n).getX()+20); // 实现曲线往前走 } try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } g1.clearRect(0, 0, 510, 300); //每次画完之后清屏 if(h==MyList_copy2.size()) cycle=false; //画完之后，退出循环 h++; j=h; } Live=false; //可能是因为用了线程（第200行），所以这里在把Live设为false } }