通过实例可以更好的了解java

18-例子1
import java.applet.*; import java.awt.*; import java.awt.event.*;
public class Example18_1 extends Applet implements MouseListener
{  TextField text;
  public void init()
  { text=new TextField(40); add(text);
    addMouseListener(this) ;//向小程序增加监视。 
  }   
  public void mousePressed(MouseEvent e)
  {text.setText("鼠标键按下了,位置是"+e.getX()+","+e.getY() );
  } 
  public void mouseReleased(MouseEvent e)
  { text.setText(" 鼠标松开了,位置是"+e.getX()+","+e.getY() );
  }
  public void mouseEntered(MouseEvent e)
  {text.setText(" 鼠标进来了,位置是"+e.getX()+","+e.getY() );
  }
  public void mouseExited(MouseEvent e)
  {text.setText(" 鼠标走开了");
  }
  public void mouseClicked(MouseEvent e)
  { if(e.getClickCount()==2)
     { text.setText("鼠标键双击,位置:"+e.getX()+","+e.getY());
     }  
    else {}
  }
}



18-例子2
import java.applet.*;import java.awt.*;import java.awt.event.*;
public class Example18_2 extends Applet implements MouseListener
{  TextField text;int x;
  public void init()
  {  x=5;  text=new TextField(40); add(text);
    addMouseListener(this) ;//小程序监视小程序容器中的鼠标事件。
  }   
 public void paint(Graphics g)
 { x=x+3; g.drawOval(10,10,x,x);
 }   
 public void mousePressed(MouseEvent e)
  {text.setText("鼠标键按下了,位置是"+e.getX()+","+e.getY() );
   repaint();   //调用这个方法时，程序将清除paint()方法以前所
                   //画的内容，并再调用paint()方法。
  } 
  public void mouseReleased(MouseEvent e)
  { text.setText(" 鼠标松开了,位置是"+e.getX()+","+e.getY() );
  }
  public void mouseEntered(MouseEvent e)
  {text.setText(" 鼠标进来了,位置是"+e.getX()+","+e.getY() );
  }
  public void mouseExited(MouseEvent e)
  {text.setText(" 鼠标走开了");
  }
  public void mouseClicked(MouseEvent e)
  { if(e.getClickCount()==2)
     { text.setText("鼠标键双击,位置:"+e.getX()+","+e.getY());
     }  
    else {}
  }
}



18-例子3
import java.applet.*;import java.awt.*;
import java.awt.event.*;
public class  Example18_3 extends Applet implements MouseListener
{ double x,y;
 public void init()
 {x=-1;y=-1; addMouseListener(this); 
 }
 public void paint(Graphics g)
 {if(x!=-1&&y!=-1 &&x>=80) 
   {g.setColor(Color.blue);  
   g.drawOval((int)x,(int)y,10,10);
   }
  else if (x!=-1&&y!=-1&& x<80&&x>40 ) 
   {g.setColor(Color.red);  
    g.drawString("小心地雷",(int)x+5,(int)y+5); 
    g.drawString("往右走",(int)x+5,(int)y+15);
  }
 else if (x!=-1&&y!=-1&& x<=40 ) 
   {g.setColor(Color.red);  
    g.drawString("地雷爆炸",(int)x+15,(int)y+5); 
     g.fillOval((int)x,(int)y,20,20);
  }
}
 public void mousePressed(MouseEvent e)
 { x=e.getX();y=e.getY();
   repaint();
}
 public void mouseReleased(MouseEvent e)
 {}
 public void mouseEntered(MouseEvent e)
 {}
 public void mouseExited(MouseEvent e)
 {}
 public void mouseClicked(MouseEvent e)
 {}
}  



18-例子4
import java.applet.*;import java.awt.*;import java.awt.event.*;
public class Example18_4 extends Applet implements MouseListener
{  TextField text;int x,y,tom;
  public void init()
  {  x=5; tom=0; text=new TextField(40);
    add(text);addMouseListener(this) ;//向小程序增加监视器。 
  }   
 public void paint(Graphics g)
  {if(tom==1)
    {g.setColor(Color.red); 
     g.fillOval(10+(int)x,10+(int)y,15,15);
     g.setColor(Color.green); g.fillOval(100,100,30,30);
     g.setColor(Color.red); g.fillOval(120,120,35,35);
    }   
   else if(tom==-1)   
    {g.setColor(Color.pink); g.fillOval(100,100,50,50);  
     g.setColor(Color.white); g.fillOval(120,120,45,45); 
    }
   else if(tom==2)
    { g.setColor(Color.red);
     g.drawString("来了,漫画带来了吗？",80,120);   
    }
   else if(tom==-2)
    { g.setColor(Color.green);
     g.drawString("欢迎再来，别忘了关门",80,120);   
    }
} 
public void mousePressed(MouseEvent e)
  { tom=1; x=e.getX(); y=e.getY();
    text.setText("鼠标键按下了,位置是"+e.getX()+","+e.getY() );
   repaint();  
  } 
  public void mouseReleased(MouseEvent e)
  { tom=-1;text.setText(" 鼠标松开了,位置是"+e.getX()+","+e.getY() );
    repaint(); 
  }
  public void mouseEntered(MouseEvent e)
  {tom=2; text.setText(" 鼠标进来了,位置是"+e.getX()+","+e.getY() );
   repaint();
  }
  public void mouseExited(MouseEvent e)
  {tom=-2; text.setText(" 鼠标走开了");
   repaint();
  }
  public void mouseClicked(MouseEvent e)
  { if(e.getClickCount()==2)
     { text.setText("鼠标键双击,位置:"+e.getX()+","+e.getY());
     }  
  }
}



18-例子5
import java.applet.*;import java.awt.*;
import java.awt.event.*;
public class Example18_5 extends Applet implements MouseListener
{ TextField text;
  public void init()
  { text=new TextField(40);
    add(text);addMouseListener(this) ;//向小程序增加监视器。
  }   
  public void mousePressed(MouseEvent e)
  { if(e.getModifiers()==InputEvent.BUTTON3_MASK)
    text.setText("鼠标右键按下了,位置是"+e.getX()+","+e.getY() );
   else if(e.getModifiers()==InputEvent.BUTTON1_MASK)
    text.setText("鼠标left按下了,位置是"+e.getX()+","+e.getY() );
  } 
  public void mouseReleased(MouseEvent e)
  { }
  public void mouseEntered(MouseEvent e)
  { }
  public void mouseExited(MouseEvent e)
  {}
  public void mouseClicked(MouseEvent e)
  { }  
}



18-例子6
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Example18_6 extends Applet implements MouseMotionListener
{ TextField text;
 public void init()
 { text=new TextField();
   setLayout(new BorderLayout());
   setBackground(Color.green);
   addMouseMotionListener(this); add(text,"South");
 }
 public void mouseDragged(MouseEvent e)
 {text.setBackground(Color.red); 
  text.setText("鼠标的坐标:"+"("+e.getX()+","+e.getY()+")");
 }
 public void mouseMoved(MouseEvent e)
 {text.setBackground(Color.blue);
  text.setText("鼠标的坐标:"+"("+e.getX()+","+e.getY()+")");
 } 
}




18-例子7
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class Example18_7 extends Applet implements MouseListener
{  TextArea text;Button button;
  public void init()
  { button=new Button("我上面也能发生鼠标事件");
    button.addMouseListener(this);
    text=new TextArea();
    text.addMouseListener(this);
    setLayout(new BorderLayout());
    add(button,"North");add(text,"Center");
  }
  public void mousePressed(MouseEvent e)
  { if(e.getSource()==button)
       {text.setText("按钮发生鼠标事件"+"("+e.getX()+","+e.getY()+")");
       }
    else if(e.getSource()==text)
       {text.setText("\n"+"文本区发生鼠标事件"+"("+e.getX()+","+e.getY()+")");
       }
  }
 public void mouseReleased(MouseEvent e)
  { text.setText("鼠标释放位置:"+"("+e.getX()+","+e.getY()+")");
  }
 public void mouseEntered(MouseEvent e)
  { text.setText("鼠标进入位置:"+"("+e.getX()+","+e.getY()+")");
  }
 public void mouseExited(MouseEvent e)
  { text.setText("鼠标退出位置:"+"("+e.getX()+","+e.getY()+")");
  }
 public void mouseClicked(MouseEvent e)
  { text.setText("鼠标点击位置:"+"("+e.getX()+","+e.getY()+")");
  }
} 



18-例子8.
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class  Example18_8 extends Applet implements MouseListener
{ double x,y;
 public void init()
 {x=-1;y=-1;  addMouseListener(this); 
 }
 public void mousePressed(MouseEvent e)
 {x=e.getX();y=e.getY();
  if(0<=x&&x<=50&&0<=y&&y<=50)
  {setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));}
  }
 public void mouseReleased(MouseEvent e)
 {x=e.getX();y=e.getY();
  if(!(0<=x&&x<=50&&0<=y&&y<=50))
  {setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));}
 }
 public void mouseEntered(MouseEvent e)
 {setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));}
 public void mouseExited(MouseEvent e) {}
 public void mouseClicked(MouseEvent e) {}
}



18-例子9 
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Example18_9 extends Applet implements MouseMotionListener
{ int x=-1,y=-1;
  public void init()
 { setBackground(Color.green);
   addMouseMotionListener(this); 
 }
 public void paint(Graphics g)
 {if(x!=-1&&y!=-1)
  {g.setColor(Color.red);
   g.drawLine(x,y,x,y);
  }
 }
public void mouseDragged(MouseEvent e)
 {x=(int)e.getX();y=(int)e.getY();
  repaint();
 }
 public void mouseMoved(MouseEvent e)
  {} 
 public void update(Graphics g)
  { paint(g);
  } 
}



18-例子10
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Example18_10 extends Applet
implements ActionListener,
MouseMotionListener
{ int x=-1,y=-1,橡皮擦通知=0,清除通知=0;
  Color c=new Color(255,0,0);int con=3;
  Button b_red,b_blue,b_green,
  清除,b_quit;
  public void init()
 {addMouseMotionListener(this); 
  b_red=new Button("画红色图形");  b_blue=new Button("兰色图形"); 
  b_green=new Button("画绿色图形");  b_quit=new Button("橡皮");
  清除=new Button("清除");
  add(b_red); add(b_green); add(b_blue); add(b_quit);add(清除);
  b_red.addActionListener(this); b_green.addActionListener(this);
  b_blue.addActionListener(this); b_quit.addActionListener(this);
  清除.addActionListener(this);
 }
 public void paint(Graphics g)
 {if(x!=-1&&y!=-1&&橡皮擦通知==0&&清除通知==0)
  {g.setColor(c); g.fillOval(x,y,con,con);
  }
  else if(橡皮擦通知==1&&清除通知==0)
  {g.clearRect(x,y,10,10);
  }
  else if(清除通知==1&&橡皮擦通知==0)
  {g.clearRect(0,0,getSize().width,getSize().height);
  }
 }
public void mouseDragged(MouseEvent e)
 {
  x=(int)e.getX();y=(int)e.getY(); repaint();
 }
 public void mouseMoved(MouseEvent e)
 { } 
 public void update(Graphics g)
 { paint(g);
 } 
 public void actionPerformed(ActionEvent e)
 {if(e.getSource()==b_red)
  { 橡皮擦通知=0;清除通知=0; c=new Color(255,0,0);
  }
  else if(e.getSource()==b_green)
  {橡皮擦通知=0;清除通知=0;  c=new Color(0,255,0);
  }
  else if(e.getSource()==b_blue)
  { 橡皮擦通知=0;清除通知=0; c=new Color(0,0,255);
  }
  if(e.getSource()==b_quit)
  {橡皮擦通知=1;清除通知=0 ;
  }
  if(e.getSource()==清除)
  {清除通知=1; 橡皮擦通知=0;repaint();
  }
 }
}




18-例子11
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Example18_11 extends Applet implements KeyListener
{Button b=new Button("我在这里");
 public void init()
 {addKeyListener(this);//小程序(容器)获得处理键盘事件的监视器。
  add(b);
 }
 public void keyPressed(KeyEvent e)
 {if(e.getKeyCode()==KeyEvent.VK_A)//判断是否按下了a字符键。
  {b.setBounds(50,60,100,100); 
   b.setBackground(Color.red);}
  } 
 public void keyTyped(KeyEvent e)
 {}
 public void keyReleased(KeyEvent e)
 {}
}



18-例子12
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class Example18_12 extends Applet implements KeyListener
{Button b=new Button("我能被移动");
 int b_x=0,b_y=0;
 public void init()
 {b.addKeyListener(this);//按钮获得键盘事件监视器.
  setLayout(null);
  add(b);
  b.setBounds(20,20,70,30); 
  b_x=b.getBounds().x;b_y=b.getBounds().y;//获取按钮左上角的x,y坐标
 }
 public void keyTyped(KeyEvent e)
 {
 } 
 public void keyPressed(KeyEvent e)
 {if(e.getKeyCode()==KeyEvent.VK_UP)
    {b_y=b_y-2;
     if(b_y<=0) b_y=0;
     b.setLocation(b_x,b_y);
    }
 else if(e.getKeyCode()==KeyEvent.VK_DOWN)
    {b_y=b_y+2;
     if(b_y>=300) b_y=300; 
     b.setLocation(b_x,b_y);
    }
 else if(e.getKeyCode()==KeyEvent.VK_LEFT)
    {b_x=b_x-2;
     if(b_x<=0) b_x=0;
     b.setLocation(b_x,b_y);
    } 
 else if(e.getKeyCode()==KeyEvent.VK_RIGHT)
    {b_x=b_x+2;
     if(b_x>=300) b_x=300;
     b.setLocation(b_x,b_y);
    }
  
 }
 public void keyReleased(KeyEvent e)
 {}
}



18-例子13
import java.applet.*;import java.awt.*;import java.awt.event.*;
public class Example18_13 extends Applet implements KeyListener,ActionListener
{Label label=new Label("点击一个积木，然后移动它");
 Button b[]=new Button[40];
 int x[]=new int[40];
 int y[]=new int[40];
 String s=null;
 public void init()
 { setLayout(null);
   add(label);
   label.setBounds(0,0,150,30); 
  int k1=70,k2=70,k3=70,k4=70;
  for(int i=0;i<40;i++)
  {b[i]=new Button(String.valueOf(i));
   if(i%3==0) b[i].setBackground(Color.red);
   if(i%3==1) b[i].setBackground(Color.blue);
   if(i%3==2) b[i].setBackground(Color.yellow);
   b[i].addKeyListener(this);//按钮获得键盘事件监视器.
   b[i].addActionListener(this); add(b[i]);