实际Java编程中的经验教训

王朝java/jsp·作者佚名  2008-05-19
窄屏简体版  字體: |||超大  

作者:cctech

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\1c2njavajavac 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\1c2njavajavac 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

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JAVA2P437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);

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()));

}

}

jiangns3003兄弟还告诉了以下的方法:兄弟,你的这个方案太复杂了。你的目的是:glasspane显示,但不想处理事件(这时事件将自动

 
 
 
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