j2me翻页例子
//执行类
public class Test extends MIDlet{
private Display display;
private TextCanvas tcanvas;

public Test() {
// TODO Auto-generated constructor stub
display=Display.getDisplay(this);
tcanvas=new TextCanvas(this);
}

protected void startApp() throws MIDletStateChangeException {
display.setCurrent(tcanvas);

}

protected void pauseApp() {
// TODO Auto-generated method stub

}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
// TODO Auto-generated method stub

}

}


//翻页实现类

public class TextCanvas extends Canvas {

InputStream is;
InputStreamReader ir;
int b=0,page=1,num=-1;
private int count=0;
private String str=new String();
private String ss=new String();
private static final int MAX_SIZE=10;


public TextCanvas(Test test) {
str=this.getText();
System.out.println("--text.size--"+str.length());
}

protected void paint(Graphics g) {
// TODO Auto-generated method stub
int x = 0;
int y = 0;
//设置画布颜色
// g.setColor(0xD8d8BF);
// g.fillRect(0,0,this.getWidth(),this.getHeight());

g.setColor(255, 255, 255);
g.fillRect(0, 0, getWidth(), this.getHeight());

ss=this.TurnPage(count);
g.setColor(0x000000);//设置内容颜色
g.drawString(ss, x, y,Graphics.LEFT|Graphics.TOP);
}

protected void keyPressed(int keyCode){

//4向前翻页，6向后翻页；
if(keyCode==Canvas.KEY_NUM6){
System.out.println("-------6向后翻页--------");
this.changePage(page);
page++;
this.repaint();
}
else if(keyCode==Canvas.KEY_NUM4){
System.out.println("---------4向前翻页----------");
this.changePage(page-1);
page--;
this.repaint();
}
}

//翻页功能pageNum==1时向下翻一页，pageNum==-1时向上翻一页
public int changePage(int pageNum){

System.out.println("--前count--/"+count+"----pageNume----/"+pageNum);
if(page>=1){
count=MAX_SIZE*pageNum;
} else if(page <1){
count=0;
}
System.out.println("--后count--/"+count);
return count;
}

//截取当前页字符串
protected String TurnPage(int start){
String temp="";
int end=start+MAX_SIZE;
int ks=start;
System.out.println(ks+"/"+end);
if(end<=str.length()){
temp=str.substring(ks,end);
}else if(ks<str.length()){
temp=str.substring(ks);
}else{
temp="文本已读完！！";
}
System.out.println("------str---"+temp+"-currentPage--/"+page);
return temp;
}


// 获取文件中的字符将其放入字符串对象中
protected String getText(){

is = getClass().getResourceAsStream("/a.txt");
ir=new InputStreamReader(is);

if (null != is) {
int ch = 0;
try {
while ((ch = ir.read()) != -1) {
str=str.concat(String.valueOf((char)ch));
}
} catch (IOException e) {
e.printStackTrace();
}
// System.out.println("-------获取文件中的字符---"+str);
return str;
} else {
return null;
}
}


}