11级_Java_曹建波5.08 滚动组件&菜单组件

滚动组件

AWT中的滚动组件包括Scrollbar（滚动条）和滚动面板（ScrollPane）两种。

滚动条ScrollBar：在指定的取值范围内快速选取某一值的功能。

构造方法
public Scrollbar(int orientation,int value,int visible,int minimum,int maximum)

参数orientation的取值：Scrollbar.HORIZONTAL表示水平滚动条；Scrollbar.VERTICAL表示垂直滚动条。

常用方法
public void setValue(int value);
public int getValue();
public void setBlockIncrement(int value);
public void setUnitIncrement(int value);

触发事件
当用户通过鼠标操作（比如拖动滑块位置）来改变滚动条中滑块的位置时，会触发AdjustmentEvent类型事件，对应的监听接口为：AdjustmentListener，事件处理方法：
public void adjustmentValueChanged( AdjustmentEvent e);

滚动条注册或删除事件监听的方法：
public void addAdjustmentListener(AdjustmentListener l);
public void removeAdjustmentListener(AdjustmentListener l);

示例3：实现调色板功能。

package com.hbsi;

import java.awt.*;

import java.awt.event.*;

publicclassTestScrollbarextends FrameimplementsAdjustmentListener{

TextFieldtfr,tfg,tfb;

Scrollbarsbr,sbg,sbb;

Paneldisplay,p1;

public TestScrollbar(){

super("滚动条");

display=new Panel();

Panelpcolor=new Panel();

pcolor.setLayout(new GridLayout());

Panelpw=new Panel();

pw.setLayout(new GridLayout(3,2));

tfr=new TextField("255");

tfg=new TextField("255");

tfb=new TextField("255");

tfr.setEditable(false);

tfg.setEditable(false);

tfb.setEditable(false);

pw.add(tfr);

pw.add(new Label("红色"));

pw.add(tfg);

pw.add(new Label("绿色"));

pw.add(tfb);

pw.add(new Label("蓝色"));

sbr=newScrollbar(Scrollbar.HORIZONTAL,255,10,0,255);

sbg=newScrollbar(Scrollbar.HORIZONTAL,255,10,0,255);

sbb=newScrollbar(Scrollbar.HORIZONTAL,255,10,0,255);

sbr.setName("SBR");

sbg.setName("SBG");

sbb.setName("SBB");

sbr.setBackground(Color.red);

sbg.setBackground(Color.green);

sbb.setBackground(Color.blue);

p1=new Panel();

p1.setLayout(new GridLayout(3,1));

p1.add(sbr);

p1.add(sbg);

p1.add(sbb);

sbr.addAdjustmentListener(this);

sbg.addAdjustmentListener(this);

sbb.addAdjustmentListener(this);

pcolor.add(pw,BorderLayout.WEST);

pcolor.add(p1,BorderLayout.CENTER);

add(display,BorderLayout.CENTER);

add(pcolor,BorderLayout.SOUTH);

setBounds(200,200,400,300);

setVisible(true);

addWindowListener(new WindowAdapter(){

publicvoidwindowClosing(WindowEvent e) {

System.exit(0);

}

});

}

publicstaticvoid main(String[]args) {

//TODO Auto-generatedmethod stub

new TestScrollbar();

}

@Override

publicvoidadjustmentValueChanged(AdjustmentEvent e) {

//TODO Auto-generatedmethod stub

int r,g,b;

r=sbr.getValue();

g=sbg.getValue();

b=sbb.getValue();

Colorc=new Color(r,g,b);

display.setBackground(c);

Stringsb_name=((Scrollbar)e.getSource()).getName();

if(sb_name.equals("SBR")){

tfr.setText(Integer.toString(r));

}elseif(sb_name.equals("SBG")){

tfg.setText(Integer.toString(g));

}elseif(sb_name.equals("SBB")){

tfb.setText(Integer.toString(b));

}

}

}

菜单组件

菜单组件包括包括MenuBar（菜单条）、Menu（菜单）、MenuItem（菜单项）、CheckboxMenuItem（带复选框的菜单项）和PopupMenu（弹出式菜单）。

菜单条MenuBar
MenuBar mb=new MenuBar();
frame.setMenuBar(mb);

菜单Menu
Menu mnFile=new Menu(“文件”);
Menu mnEdit=new Menu();
mb.add(mnFile);
mb.add(mnEdit);

菜单项MenuItem
public MenuItem();
public MenuItem(String label);
public MenuItem(String label,MenuShortcut s);

MenuItem miOpen=new MenuItem(“打开”);
MenuShortcut msc=new MenuShortcut(KeyEvent.VK_E);
MenuItem miExit=new MenuItem(“退出”,msc);
mnFile.add(miOpen);
mnFile.addSeparator();
mnFile.add(miExit);

菜单项触发的事件：ActionEvent

二级菜单和复选菜单项

二级菜单：菜单中嵌套菜单

复选菜单项（CheckboxMenuItem）

注意：用鼠标单击复选菜单项引发的事件是ItemEvent，因此要具体实现的监听接口为ItemListener。

示例4 记事本应用程序。

package com.hbsi;

import java.awt.*;

import java.awt.event.*;

import java.io.*;

publicclassTestMenu extends Frameimplements ActionListener{

TextAreata;

MenuBarmb;

MenumnFile,mnEdit,mnFormat,mnHelp,mnSaveAs;

MenuItemmfNew,mfOpen,mfSave,mfLocal,mfWeb,mfExit;

MenuItemmeUndo,meCut,meCopy,mePaste,meDelete,meFind,meReplace,meSelectAll;

FileDialogopenDialog,saveDialog;

Filefile;

public TestMenu(){

super("我的记事本");

ta=new TextArea("",20,20);

add(ta,BorderLayout.CENTER);

mb=new MenuBar();

mnFile=new Menu("文件(F)");

//Font f=newFont("华文行楷",Font.BOLD,12);

//mnFile.setFont(f);

mnEdit=new Menu("编辑(E)");

mnFormat=new Menu("格式(O)");

mnHelp=new Menu("帮助(H)");

mfNew=new MenuItem("新建(N)");

mfNew.setShortcut(newMenuShortcut(KeyEvent.VK_N));

mfOpen=new MenuItem("打开(O)...");

mfOpen.setShortcut(newMenuShortcut(KeyEvent.VK_O));

mfSave=new MenuItem("保存(S)");

mfSave.setShortcut(new MenuShortcut(KeyEvent.VK_S));

mnSaveAs=new Menu("保存为(A)...");

mfLocal=new MenuItem("本地");

mfWeb=new MenuItem("Web");

mfExit=new MenuItem("退出(X)");

mfExit.setShortcut(newMenuShortcut(KeyEvent.VK_X));

meUndo=new MenuItem("撤消(U)");

meUndo.setShortcut(newMenuShortcut(KeyEvent.VK_Z));

meCut=new MenuItem("剪切(T)");

meCut.setShortcut(newMenuShortcut(KeyEvent.VK_X));

meCopy=new MenuItem("复制(C)");

meCopy.setShortcut(newMenuShortcut(KeyEvent.VK_C));

mePaste=new MenuItem("粘贴(P)");

mePaste.setShortcut(newMenuShortcut(KeyEvent.VK_V));

meDelete=new MenuItem("删除(L)");

//meDelete.setShortcut(newMenuShortcut(KeyEvent.VK_DELETE ));

meFind=new MenuItem("查找(F)...");

meFind.setShortcut(newMenuShortcut(KeyEvent.VK_F));

meReplace=new MenuItem("替换(R)...");

meReplace.setShortcut(newMenuShortcut(KeyEvent.VK_H));

meSelectAll=new MenuItem("全选(A)");

meSelectAll.setShortcut(newMenuShortcut(KeyEvent.VK_A));

mfExit.addActionListener(this);

mfOpen.addActionListener(this);

mfSave.addActionListener(this);

setMenuBar(mb);

mnFile.add(mfNew);

mnFile.add(mfOpen);

mnFile.add(mfSave);

mnFile.addSeparator();

mnFile.add(mnSaveAs);

mnSaveAs.add(mfLocal);

mnSaveAs.add(mfWeb);

mnFile.addSeparator();//添加分隔符

mnFile.add(mfExit);

mb.add(mnFile);

mb.add(mnEdit);

mb.add(mnFormat);

mb.add(mnHelp);

mnEdit.add(meUndo);

mnEdit.add(meCut);

mnEdit.add(meCopy);

mnEdit.add(mePaste);

mnEdit.add(meDelete);

mnEdit.addSeparator();

mnEdit.add(meFind);

mnEdit.add(meReplace);

mnEdit.addSeparator();

mnEdit.add(meSelectAll);

openDialog=new FileDialog(this,"我要打开",FileDialog.LOAD);

saveDialog=new FileDialog(this,"我要保存",FileDialog.SAVE);

setBounds(300,200,400,300);

setVisible(true);

addWindowListener(new WindowAdapter(){

publicvoidwindowClosing(WindowEvent e) {

System.exit(0);

}

});

}

publicstaticvoid main(String[]args) {

new TestMenu();

}

publicvoidactionPerformed(ActionEvent e) {

/*Strings=e.getActionCommand();

if(s=="退出(X)"){

System.exit(0);

}*/

Objectobj=e.getSource();

if(obj==mfExit){

System.exit(0);

}elseif(obj==mfOpen){

openDialog.setVisible(true);

StringdirPath=openDialog.getDirectory();

StringfileName=openDialog.getFile();

if(dirPath==null||fileName==null){

return;

}

ta.setText("");

file=newFile(dirPath,fileName);

try

{

BufferedReaderbufr = new BufferedReader(new FileReader(file));

Stringline = null;

while((line=bufr.readLine())!=null)

{

ta.append(line+"\r\n");

}

bufr.close();

}

catch (IOException ex)

{

thrownew RuntimeException("读取失败");

}

}elseif(obj==mfSave){

if(file==null)

{

saveDialog.setVisible(true);

StringdirPath =saveDialog.getDirectory();

StringfileName =saveDialog.getFile();

if(dirPath==null || fileName==null)

return ;

file =newFile(dirPath,fileName);

}

try

{

BufferedWriterbufw =new BufferedWriter(new FileWriter(file));

Stringtext =ta.getText();

bufw.write(text);

//bufw.flush();

bufw.close();

}

catch (IOException ex)

{

thrownewRuntimeException();

}

}

}

}