IT博客-atskyline-BLOG-随笔分类-J2ME笔记

J2ME笔记-图片移动和旋转

atskyline — Mon, 21 Jul 2008 14:07:00 GMT

精华在于按钮事件机制

一个是长按一个是按下,另外值得一题的是除了0-9的数字键外都认为是游戏见

keyCode需要用getGameAction()转换一下在进行判断

import java.io.IOException;
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.Sprite;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;


public class MIDlet1 extends MIDlet
{
	private Display dis;
	private Mycanvas mc =new Mycanvas();



	protected void startApp() throws MIDletStateChangeException
	{
		dis=Display.getDisplay(this);
		dis.setCurrent(mc);
	}
	
	class Mycanvas extends Canvas
	{
		private Image img;
		int x,y,dir=Sprite.TRANS_NONE;;
		
		protected Mycanvas()
		{
			x=0;y=0;
			try
			{
				img=Image.createImage("/img.gif");
			} catch (IOException e)
			{
				e.printStackTrace();
			}
		}
		
		protected void paint(Graphics g)
		{
			g.setColor(255, 255, 255);
			g.fillRect(0, 0, this.getWidth(), this.getHeight());
			g.drawRegion(img, 0, 0, img.getWidth(), img.getHeight(), dir, x, y, Graphics.LEFT|Graphics.TOP);
		}
		
		protected void keyRepeated(int keyCode)
		{
			int action;
			action=this.getGameAction(keyCode);
			switch(action)
			{
				case Canvas.UP:   y-=5;break;
				case Canvas.DOWN:   y+=5;break;
				case Canvas.LEFT:   x-=5;break;
				case Canvas.RIGHT:   x+=5;break;
			}
			this.repaint();
		}
		
		protected void keyPressed(int keyCode)
		{
			int action;
			action=this.getGameAction(keyCode);
			if(action==Canvas.FIRE)
			{
				switch(dir)
				{
					case Sprite.TRANS_NONE: dir=Sprite.TRANS_MIRROR_ROT270; break;
					case Sprite.TRANS_MIRROR_ROT90: dir=Sprite.TRANS_MIRROR_ROT180; break;
					case Sprite.TRANS_MIRROR_ROT180: dir=Sprite.TRANS_MIRROR_ROT270; break;
					case Sprite.TRANS_MIRROR_ROT270: dir=Sprite.TRANS_NONE; break;
				}
				this.repaint();
			}
		}
	}
	
	protected void destroyApp(boolean unconditional)
			throws MIDletStateChangeException
	{

	}

	protected void pauseApp()
	{

	}

}

atskyline 2008-07-21 22:07 发表评论

J2ME笔记-画SIN函数图像

atskyline — Sat, 19 Jul 2008 15:20:00 GMT

Canvas类低级界面开发的一个初步程序

package DrawSin;

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class MIDlet1 extends MIDlet
{
	private Display dis;
	private Draw d = new Draw();
	
	protected void startApp() throws MIDletStateChangeException
	{
		d.setTitle("DrawSin");
		dis = Display.getDisplay(this);
		dis.setCurrent(d);		

	}
	
	class Draw extends Canvas
	{

		protected void paint(Graphics g)
		{
			g.setColor(255, 0, 0);
			g.drawLine(0, 150, 300, 150);//x轴
			g.drawLine(100, 0, 100, 300);//y轴
			int y=0;
			for(int x=0;x<=3600;x++)
			{
				y= (int)(150+10*Math.sin(x*Math.PI/180));
				g.drawLine((int)(x/10), y, (int)(x/10), y);
			}
		}
		
	}

	protected void destroyApp(boolean unconditional)
			throws MIDletStateChangeException
	{
	}

	protected void pauseApp()
	{
	}


}

atskyline 2008-07-19 23:20 发表评论

J2ME-自定义异常

atskyline — Wed, 16 Jul 2008 13:17:00 GMT

其实就是J2SE异常的那些东西.

代码中把字符串s样转换成int 明显会抛出异常

我们定义了一个继承于Exception 的自定义异常类

并将异常抛给客户端处理

import java.util.Date;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;


public class MIDlet1 extends MIDlet
{

	protected void startApp() throws MIDletStateChangeException
	{
		String s="a";
		try
		{
			this.print(s);
		} catch (CustomException e)
		{
			System.out.println(e.getMessage());
			System.out.println(e.getDate());
		}

	}
	public void print(String str) throws CustomException
	{
		try
		{
			int intValue = Integer.parseInt(str);
			int result = intValue*intValue;
			System.out.println(result);
		}
		catch(Exception ex)
		{
			CustomException ce =new CustomException("错误",new Date());
			throw ce;
		}

	}
	
	class CustomException extends Exception
	{
		private Date date;
		public CustomException(String message,Date date)
		{
			super(message);
			this.date=date;
		}
		public Date getDate()
		{
			return this.date;
		}
	}
	
	protected void destroyApp(boolean arg0) throws MIDletStateChangeException
	{

	}

	protected void pauseApp()
	{

	}

}

atskyline 2008-07-16 21:17 发表评论

J2ME笔记-退出程序

atskyline — Mon, 14 Jul 2008 14:52:00 GMT

notifyDestroyed()方法可以用来退出程序

代码如下

MIDlet1.this.notifyDestroyed();

atskyline 2008-07-14 22:52 发表评论

J2ME笔记-关于Item类及事件

atskyline — Sat, 12 Jul 2008 13:42:00 GMT

代码中演示了ChoiceGroup和TextField(列表框和文本框)的使用及其事件响应方式的使用

和Dispalyable类不同的是Item类是无法占据整个屏幕的

通常是使用Form类的append(Item item)添加到Form上的

Item的事件处理方式和Command的事件有几分类似

是通过ItemCommandListener或ItemStateListener接口实现的

一个是命令事件一个是状态改变的事件具体的使用方法参看代码

/**
* project :aboutItem
* @author atskyline
* @FirstWriteTime 2008.07.12
* @LastWriteTime 2008.07.12
*/
import javax.microedition.lcdui.Choice;
import javax.microedition.lcdui.ChoiceGroup;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Item;
import javax.microedition.lcdui.ItemCommandListener;
import javax.microedition.lcdui.ItemStateListener;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
public class MIDlet1 extends MIDlet implements ItemCommandListener,ItemStateListener
{
   private Display dis;
   private Form frm = new Form("Form");
   private ChoiceGroup cg1 =new ChoiceGroup("ChoiceGroup", Choice.POPUP);
   private TextField text1 =new TextField("TEXT1", "text1", 20, TextField.ANY);
   private TextField text2 =new TextField("TEXT2", "text2", 20, TextField.ANY);
   private Command cmdDel =new Command("删除字符",Command.ITEM,1);
   protected void startApp() throws MIDletStateChangeException
   {
      dis=Display.getDisplay(this);
      dis.setCurrent(frm);
      frm.append(cg1);
      cg1.append("选项A", null);
      cg1.append("选项B", null);
      frm.append(text1);
      frm.append(text2);
      text1.addCommand(cmdDel);
      text2.addCommand(cmdDel);
      text1.setItemCommandListener(this);
      text2.setItemCommandListener(this);
      frm.setItemStateListener(this);//注意是用frm绑定而非cg1
   }
   public void commandAction(Command c, Item item)
   {
      if(c==cmdDel)
      {
         TextField tf=(TextField)item;
         int Position=tf.getCaretPosition();
         tf.delete(Position-1, 1);
      }
   }
   public void itemStateChanged(Item item)
   {
      if(item==cg1)
      {
         String s=cg1.getString(cg1.getSelectedIndex());
         frm.setTitle(s);
      }
   }
   protected void destroyApp(boolean arg0) throws MIDletStateChangeException
   {
   }
   protected void pauseApp()
   {
   }
}