notepad.java

《精通JAVA手机游戏与应用程序设计》随书光盘

/*
 * 分页显示一篇文章
 */

package notepad;

import java.io.IOException;
import java.io.InputStream;

import javax.microedition.lcdui.*;

import javax.microedition.midlet.*;


public class NotePad extends MIDlet implements CommandListener {

	private Command exitCommand,nextCommand,beginCommand;

	private TextBox tb;
	private String str;
	private int position=0;//记录当前分段的位置

	public NotePad() {
		exitCommand = new Command("退出", Command.EXIT, 1);
		nextCommand = new Command("下一页", Command.SCREEN, 1);	
		beginCommand = new Command("重新阅读", Command.SCREEN, 1);	
		tb = new TextBox("NotePad Example", "Hello,World!", 500,TextField.ANY);
		//txt文件必须使用ascii格式保存的，否则不能显示中文
		str = loadText("/war3.txt");		
		firstText();
		
		tb.addCommand(exitCommand);		
		tb.setCommandListener(this);
		
	}
	protected void firstText(){
//		分页显示文章
		if(str.length()<=10){
			tb.setString(str);
			position = 0;
		}
		else{
			tb.setString(str.substring(0,10));
			position = 1;
			tb.addCommand(nextCommand);
			
		}	
	}
	protected String loadText(String url){
		String str = null;
		
		InputStream is = this.getClass().getResourceAsStream(url);
		try {
			byte[] data = new byte[is.available()];
			is.read(data);
			is.close();
			is=null;
			str = new String(data);
		} catch (IOException e) {			
			e.printStackTrace();
			return "";
		}
		if(str != null){			
			return str;
		}
		else
			return "";
		
	}

	protected void startApp() throws MIDletStateChangeException {
		
			
		Display.getDisplay(this).setCurrent(tb);
		

	}

	protected void pauseApp() {		

	}

	protected void destroyApp(boolean arg0) throws MIDletStateChangeException {	

	}


	public void commandAction(Command c, Displayable d) {
		if (c == exitCommand) {
			try {
				destroyApp(false);
			} catch (MIDletStateChangeException exception) {
				System.out.println("MIDletStateChangeException");
			}
			notifyDestroyed();
		}
		
		if (c == nextCommand){
			//如果存在多页
			if(str.substring(10*position).length()<10){				
				tb.setString(str.substring(10*position));	
				//消除“下一页”按钮
				tb.removeCommand(nextCommand);
				//显示“重新显示”按钮
				tb.addCommand(beginCommand);
			}
			else{				
				tb.setString(str.substring(10*position,10*position+10));
				position = position + 1;				
			}	
		}
		
		if (c == beginCommand){
			firstText();
			tb.removeCommand(beginCommand);
			tb.addCommand(nextCommand);
		}
	}
	

}