Java编程中的经验教训

我实际工作中的经验教训,在这里与大家共享
  
  空的字符串是””,不带空格
  
  outputStream  在打印时,打印的内容后面不要加\n,否则对方接受和判断不正确
  
  G:\PROJECTION\IC2N\1c2njava>javac Jsubnetframe.java
  Jsubnetframe.java:22: Jsubnetframe should be declared abstract; it does not defi
  ne valueChanged(javax.swing.event.ListSelectionEvent) in Jsubnetframe
  public class Jsubnetframe extends JFrame implements ListSelectionListener {
      ^
  Jsubnetframe.java:68: cannot resolve symbol
  symbol : class TableModel
  location: class Jsubnetframe
    TableModel dataModel = new AbstractTableModel() {  
  ^
  Jsubnetframe.java:68: cannot resolve symbol
  symbol : class AbstractTableModel
  location: class Jsubnetframe
    TableModel dataModel = new AbstractTableModel() {               
   ^
  Jsubnetframe.java:89: addActionListener(java.awt.event.ActionListener) in javax.
  swing.AbstractButton cannot be applied to (Jsubnetframe)
      cancelb.addActionListener(this);
          ^
  Note: Jsubnetframe.java uses or overrides a deprecated API.
  Note: Recompile with -deprecation for details.
  4 errors
  原因是没有import javax.swing.table.*;
  
  G:\PROJECTION\IC2N\1c2njava>javac Jhpportframe.java
  Jhpportframe.java:27: Jhpportframe should be declared abstract; it does not defi
  ne mousePressed(java.awt.event.MouseEvent) in Jhpportframe
  public class Jhpportframe extends JFrame implements
      ^
  Note: Jhpportframe.java uses or overrides a deprecated API.
  Note: Recompile with -deprecation for details.
  1 error
  Jhpportframe should be declared abstract; it does not defi   原因是因为在这里必须用MouseListener 的相关方法进行覆盖,也就是说必须加入如下的方法:
  
  public void mousePressed(MouseEvent evt) {//if (audio != null) audio.play();}
  public void mouseEntered (MouseEvent me) {}
  public void mouseExited (MouseEvent me) {}
  public void mouseReleased(MouseEvent me) {}
  
  鼠标左键和右件的事件获取:
  public void mousePressed(MouseEvent evt) {
  Point point1=evt.getPoint();
  int x,y;
    int onmask = evt.BUTTON1_DOWN_MASK;//左键的ID号
      if ((evt.getModifiersEx() & onmask ) == onmask)   // 点击左键时
      {
      }
  else                     //点击右键时
  
  
  抽象类,不能进行初始化或者生成实例
  hpportimg=new Image(getDocumentBase(),”aaa.gif”);
  这句话是错的,因为Image()是抽象类,不能进行初始化或者生成实例.,应该用:
  hpportimg=getImage(“adf.gif”);
  并且应该注意它不能放在构造函数中,而应该放在INIT()等方法中.
  
  各种动作和事件的处理:
  监视键盘的动作,用usertf.addKeyListener(this);它的接口软件包是KeyListener,应该import java.awt.event.*;  必须重载的接口函数是
  public void keyPressed(KeyEvent e){}
  public void keyReleased(KeyEvent e){}
  public void keyTyped(KeyEvent e){}
  监视焦点的动作,用usertf.add FocusListener (this);它的接口软件包是FocusListener应该import java.awt.event.*;  必须重载的接口函数是

#p#副标题#e#
  public void focusLost(FocusEvent e) { }
  public void focusGained(FocusEvent e) {}
  监视鼠标的动作,用usertf.addMouseListener(this);它的接口软件包是MouseyListener,应该import java.awt.event.*;  
  //必须增加MouseListener(this) 或component. MouseListener(this)
  
   必须重载的接口函数是
  public void mouseClicked(MouseEvent e){ }
  public void mousePressed(MouseEvent evt) {}
  public void mouseEntered (MouseEvent me) {}
  public void mouseExited (MouseEvent me) {}
  public void mouseReleased(MouseEvent me) {}
  监视鼠标移动的动作,用usertf.addMouseListener(this);它的接口软件包是MouseyMotionListener,应该import java.awt.event.*;  必须重载的接口函数是
  public void mouseMoved(MouseEvent e){}
  public void mouseDragged(MouseEvent e){ }
  以上各种事件必须在组件上增加相应的侦听,如
  user.addKeyListener(this);
    pass.addKeyListener(this);
    user.addFocusListener(this);
    pass.addFocusListener(this);
  按钮事件的执行在JAVA2中应该用下列函数,无须重载:
  public void actionPerformed(ActionEvent ae) {
   JButton source=(JButton)ae.getSource();
              if(source==okb)         
               { slkdfjalskdjflaksdjlfjads;flkjasld;kjfl;kasjdfl;k}
  
  焦点事件:focusLost(),focusGain()
  transferFocus()是将焦点传递到下一个组件
  requestFocus()是将焦点传递到指定的组件,
  if(e.getComponent()==user) user.transferFocus();
  else if(e.getComponent()==pass) pass.transferFocus();
  else if(e.getComponent()==ok) ok.transferFocus();
  经过观察发现,焦点可以在文本框上传递,但是在按钮上好象没法传递.
  
  在表格中
  subnettable.reshape(0,0,300,200); //一定要,用以刷新屏幕
  
  JTable中的每一行可否设置不同的背景颜色???
  可以的,使用自己的TableCellRenderer从TableModel中的value获取颜色值.
  请参见:
  http://www2.gol.com/users/tame/swing/examples/ 
  
  
  
  有关玻璃层:
  1、 GLASSPANE不能设置大小,它将布满整个工作区, //jtv.reshape(300,300,300,200); 没用
  2、 先建立一个JComponent 的组件,jtv=new Jtopview(jlp);其中jlp是新建母窗口的JLayeredPane
  3、 将这个组建用setGlassPane(jtv)方法设置
  4、 如果要求它透明,这一句不能少jtv.setOpaque(false);
  5、 这一句是显示的,也不能少jtv.setVisible(true);
  6、 玻璃层下面层的组建获取动作用redispatchMouseEvent(MouseEvent me)
  这段代码是我在英文网址上拿下来修改的,同时参照了<<精通JAVA2>>P437页 
  
  public void redispatchMouseEvent(MouseEvent me,boolean repaint)
  {
  //能够直接取到的组件,用广义的component 就可以了
  Point point=me.getPoint();
    int eventID = me.getID(); 
  
  Component component=jlp.getComponentAt(point); 
  Point componentPoint = SwingUtilities.convertPoint(
                      jlp,
                     point, 
                      component);
  boolean componentBOOL=component.contains(componentPoint );
  
  if(componentBOOL){
  //System.out.println(“7777777777777777” component);

#p#副标题#e#
  component.dispatchEvent(new MouseEvent(component,eventID,me.getWhen(),me.getModifiers(),
                       componentPoint.x,componentPoint.y,me.getClickCount(),me.isPopupTrigger())); 
  
               } 
  
  ////不能够直接取到的组件,用具体的组件名字
  Point alarmtablePoint = SwingUtilities.convertPoint(
                    jlp,
                    point, 
                    alarmtable);
   boolean alarmtableBOOL= alarmtable.contains(alarmtablePoint );
   if (alarmtableBOOL ) {
      alarmtable.dispatchEvent(new MouseEvent(alarmtable,eventID,me.getWhen(),
                        me.getModifiers(),
                        alarmtablePoint.x,
                        alarmtablePoint.y,
                        me.getClickCount(),
                        me.isPopupTrigger()));
    }
  }
大家提意见有没有好的方法.