第一次听说监听是三年前,做一个webGIS的项目,当时对Listener的印象就是个“监视器”,监视着界面的一举一动,一有动静就触发对应的响应。
一、概述
通过对界面的某一或某些操作添加监听,可以自发地调用监听函数/监听类,对操作作出反应。举个栗子:被监听的操作是“你惹你妈生气了”,添加的响应是“你妈给你爸打电话,你爸回家了,你爸打你一顿 ”。所以不管什么时候,只要“你惹你妈生气了”,都会触发这个操作的监听,最终结果是每次你都会被你爸打一顿。屡试不爽,无一例外。这就是事件监听,java.util.EventListener。
Listener分很多种:ActionListener,MouseListener,PopMenuListener,windowListener等等。
二、监听事件实现方式
1. 直接在控件中添加监听
如:给“保存按钮”添加ActionListener监听
1 saveCharaEditButton.addActionListener(new ActionListener() {2
3 @Override4 public void actionPerformed(ActionEvent e) {5 //TODO Auto-generated method stub
6 save();7 }8 });
2.写一个监听类,实现监听接口。
添加事件监听时只需要 添加这个监听类就ok了。【PS:这个内部类与函数并列写就可以,不用另建类文件,只是前面注意不要加public修饰符。默认只能有一个public类。】
1 publicJPanel setRightPanel(){2 JPanel rightPanel = newJPanel();3 double[][] size = {{15,TableLayout.FILL,30,TableLayout.FILL,35},{10,30,10,TableLayout.FILL}};4 rightPanel.setLayout(newTableLayout(size));5 JButton saveCharaEditButton = new JButton("保存编辑");6 JButton enableCharaEditButton = new JButton("启用编辑");7 rightPanel.add(enableCharaEditButton, "1,1");8 rightPanel.add(saveCharaEditButton, "3,1");9 rightPanel.add(setCharaJCTablePanel(), "0,3,4,3");10 saveCharaEditButton.addActionListener(new saveEditToFloodCharacterValueListener());//添加监听
11 returnrightPanel;
12 }
1 class saveEditToFloodCharacterValueListener implements ActionListener{2
3 @Override4 public void actionPerformed(ActionEvent e) {5 //TODO Auto-generated method stub
6 FloodCharacterValue floodCharacterValue = newFloodCharacterValue();7 floodCharacterValue =FloodCharacterValue.transFldPropToFloodCharacterValue(editCharaFldprop);8 m_doc.m_floodExtractCharacterValue =floodCharacterValue;9 }10 }
3. 添加适配器,也可以实现监听。(其实方法同1)
首先说一下适配器和监听接口的不同:new一个监听接口,需要重载该接口下面的所有方法,你删除任何一个,都会报错;但是适配器可以只重载你需要的那个方法。
以windowListener为例,给对话框dialog添加监听addWindowListerner,然后监听内容为窗口适配器WindowAdapter。对比如下:
(1)监听接口【默认重载所有方法,功能需求单一时不推荐】
dialog.addWindowListener(newWindowListener() {
@Overridepublic void windowOpened(WindowEvent e) {//TODO Auto-generated method stub}
@Overridepublic void windowIconified(WindowEvent e) {//TODO Auto-generated method stub}
@Overridepublic void windowDeiconified(WindowEvent e) {//TODO Auto-generated method stub}
@Overridepublic void windowDeactivated(WindowEvent e) {//TODO Auto-generated method stub}
@Overridepublic void windowClosing(WindowEvent e) {//TODO Auto-generated method stub}
@Overridepublic void windowClosed(WindowEvent e) {//TODO Auto-generated method stub}
@Overridepublic void windowActivated(WindowEvent e) {//TODO Auto-generated method stub}
});
(2)添加适配器【可以只重载需要的方法,功能单一时推荐】
1 dialog.addWindowListener(new WindowAdapter() {2 @Override3 public void windowClosed(WindowEvent e) {4 //TODO Auto-generated method stub
5 JDialog dialog2 =(JDialog) e.getSource();6 set_infoSectionList(update_infoSectionListByProp(prop));7 if (basinCheckList != null && !basinCheckList.isEmpty() && basinCheckList.get(0).getCHECKED()==1) {8 tableCharaShowPanel.updateData(schemeType, get_infoSectionList(), false);9 }else{10 tableCharaShowPanel.updateData(schemeType, get_infoSectionList(), true);11 }12 super.windowClosed(e);13 dialog2.dispose();14 }15 });
另外,关于添加哪些适配器,可以选择WindowAdapter,右键菜单中选择-resources-override/implement methods... - 勾选需要添加的方法即可。
4. 添加全局控件的监听
背景:leftSecTypeList,rightSecTypeList,leftButton,rightButton 是this的全局控件变量。现在给他们添加鼠标点击监听.
这种操作一般分为两步:
(1)在初始化该控件的时候,添加参数为this的鼠标监听。
leftSecTypeList.addMouseListener(this);
(2)重写mouseClicked(MouseEvent e)函数,根据e.getSource() 判断是触发鼠标点击的是哪个控件,给出相应的反应。
1 publicJPanel createSelPanel(){2 JPanel panel = newJPanel();***22 leftSecTypeList.addMouseListener(this);23 rightSecTypeList.addMouseListener(this);24 leftButton.addMouseListener(this);25 rightButton.addMouseListener(this);26 returnpanel;27 }
1 @Override2 public void mouseClicked(MouseEvent e) {3 //TODO Auto-generated method stub
4 Object sourceObject =e.getSource();5 if (sourceObject == leftSecTypeList&& e.getClickCount() == 2) {6 HFSection section =leftSecTypeList.getSelectedItemType();
9 }else if (sourceObject == rightSecTypeList&& e.getClickCount() == 2) {10 HFSection section =rightSecTypeList.getSelectedItemType();11 }else if (sourceObject ==leftButton) {12
13 }else if (sourceObject ==rightButton) {14
15 }16 }
5.利用类AbstractButton的set/get动作命令。
void
string
//创建菜单Item的函数
privateJMenuItem createMenuItem(String text,String actionCommand)
{
JMenuItem item= newJMenuItem(text);
item.setActionCommand(actionCommand);//设置此按钮的动作命令
item.addActionListener(newMenuActionListener());returnitem;
}
//创建菜单
private voidinitPopupMenu()
{
layerPopupMenu= newJPopupMenu();
layerPopupMenu.add(createMenuItem("添加目录","addDir"));
layerPopupMenu.add(createMenuItem("添加图层","addLayer"));
layerPopupMenu.addSeparator();
layerPopupMenu.add(createMenuItem("上移","up"));
layerPopupMenu.add(createMenuItem("下移","down"));
}
// 右键菜单操作命令 class MenuActionListenerimplementsActionListener
{
@Overridepublic voidactionPerformed(ActionEvent e)
{
String actionCommand=e.getActionCommand();if(actionCommand.equals("addDir")){ addDir();}else if(actionCommand.equals("addLayer")){ addLayer();}else if(actionCommand.equals("up")){ layerUp();}else if(actionCommand.equals("down")){ layerDown();}
}
6. 以接口实现对按钮的监听响应
1.在工具条面板中:(1)定义响应接口 (2)以接口定义响应变量 (3)定义按钮,监听响应为变量
2.在调用文件中: 以implents方式实现 工具条面板中对应的接口变量
//1-1 ControlBarPanel.java 定义接口
public interfaceIBackwardActionPerformed{public voidActionPerformed(ActionEvent e);
}//1-2 ControlBarPanel.java 以接口定义响应变量
publicIBackwardActionPerformedbackwardActionPerformed;//1-3 ControlBarPanel.java 定义按钮,监听响应为变量
backwardButton.addActionListener(newActionListener() {
@Overridepublic voidactionPerformed(ActionEvent e) {//TODO Auto-generated method stub
backwardActionPerformed.ActionPerformed(e);
}
});//2-1 MainForcastPanel.java 实现响应变量具体操作
controlBarPanel.backwardActionPerformed= newBackwardBtnActionListener();//2-2 MainForcastPanel.java 实现响应变量具体操作
class BackwardBtnActionListener implementsIBackwardActionPerformed,Runnable {
@Overridepublic voidActionPerformed(ActionEvent e) {//TODO Auto-generated method stub
Thread thread = new Thread(this);new HFProgressPane1(thread, "正在计算中......", null, null);
}
@Overridepublic voidrun() {//TODO Auto-generated method stub
************}
}
3. 方法6的详细代码
1 public class ControlBarPanel extends JPanel implementsActionListener{2 private JButton jButton;
3 publicIActionPerformed iActionPerformed;4
5 publicJPanel createPanel(){6 JPanel panel = newJPanel();7 panel.setLayout(new FlowLayout(FlowLayout.LEFT, 2, 0));8 jButton = new JButton("testButton");9 jButton.setMargin(new Insets(0, 0, 0, 0));10 jButton.addActionListener(newActionListener() {11 @Override12 public voidactionPerformed(ActionEvent e) {13 //TODO Auto-generated method stub
14 iActionPerformed.ActionPerformed(e);15 }16 });17 panel.add(createForeTypePanel());18 panel.add(jButton);19 returnpanel;20 }21
22 public interfaceIActionPerformed {23 public voidActionPerformed(ActionEvent e);24 }25 }26
27 public class ShowPanel extendsJPanel {28 privateControlBarPanel controlBarPanel;29 //构造函数
30 publicShowPanel() {31 controlBarPanel = newControlBarPanel();32 controlBarPanel.iActionPerformed = newActionListener();33 this.setLayout(newBorderLayout());34 this.add(controlBarPanel,BorderLayout.NORTH);35 }36
37 class ActionListener implementsIActionPerformed{38 @Override39 public voidActionPerformed(ActionEvent e) {40 //TODO Auto-generated method stub
41 function(e);42 }43 }44 }
7. 添加监听列表,然后通知所有监听。
分为三步
(1)定义变量:监听列表
(2)定义函数:注册监听,删除监听
(3)定义函数:通知所有监听
代码如下:
1 /**
2 * 拖动完成后监听保存队列3 */
4 private List dragOverListenerList =newArrayList();5
6 /**
7 * 注册监听事件8 */
9 public voidaddDragOverListener(DragOverListener listener){10 synchronized(objSync) {11 dragOverListenerList.add(listener);12 }13 }14
15 /**
16 * 删除监听17 *@parameventObject18 */
19 public voidremoveDragOverListener(DragOverListener listener){20 synchronized(objSync) {21 dragOverListenerList.remove(listener);22 }23 }24
25 /**
26 * 通知所有监听事件27 */
28 private voidnotifyAllListener(){29 for(int i=0;i
在需要调用监听的地方,添加通知监听事件的函数即可。
四、小结
以上是一些Java事件监听与使用方法的一些介绍,属于入门级别。高级应用后期再予以学习与记录。
写于1月6日
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