public class Log{
   private static final String filePath = PropertyReader.getResource("Log_File_Path");//Supposing we have define in the last ProperyReader class and the file
  
   public static final String EXCEPTION                  =   "Exception";
   public static final String CREATE_STAFF           =   "Create Staff";
   public static final String EDIT_STAFF                 =   "Edit Staff";
   public static final String DELETE_STAFF            =   "Delete Staff";
   public static final String RECORD_HAS_EXIST  =   "Record Has Exist";

   public static void log(String msg_type, Exception e){
      StringBuffer errMsg = new StringBuffer(e.toString);
     
      for(int i=0;i<e.getStackTrace().length;i++){
         errMsg.append("\n\t at");
         errMsg.append(e.getStackTrace()[i].toString);
      }
      log(msg_type,errMsg.toString());
      OptionPanel.showErrMsg("Sorry,System may have an error \n System will exit");
      System.exit(-1);
   }

  public static void log(String msg.type,Staff staff){
     String msg = null;
     if(msg_type == CREATE_STAFF){
         msg = staff.toString() + "has benn created";
     }else if(msg_type == EDIT_STAFF){
         msg = staff.toString() + "has been Changed";
     }else if(msg_type == DELETE_STAFF){
         msg = staff.toString() + "has been Deleted";
     }else if(msg_type == RECORD_HAS_EXIST){
         msg = staff.toString() + "has exist in the database";
     }
     log(msg_type,msg);
  }

  private static void log(String msg_type,String msg){
      BufferedWriter out = null;
      DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM);
     
      try{
        out = new BufferedWriter(new FileWriter(getLogFilePath(),true));//如果为 true，则将字节写入文件末尾处，而不是写入文件开始处
        out.write("["+df.format(new Date()) + "] <" + msg_type + "> :" + msg);
        out.newline();
        out.newline();
      }catch(IOException e){
          e.printStackTrace();
      }finally{
         try{
           if(out!=null){
              out.close();
           }
         }catch(IOException e){
            e.printStackTrace();
         }
      }
  }

  private static String getLogFilePath(){
     File logDir = new File(filePath);
     if(!logDir.exists()){
       logDir.mkdir();
     }
    
     int i = 1;
     String fileName = filePath + "log_";
     File file = new File(fileName + i + ".txt");
   
     while(file.exists() && file.length() > 30000L) {
         i++;
         file = new File(fileName + i + ".txt");
     }
   
      return fileName + i + ".txt"
  }
}

//*****************************The OptionPanel Dialog Class for the Log Class
import javax.swing.JOptionPane;

public class OptionPanel {
   private static final String appTitle = PropertyReader.getResource("App_Title");//suposing the file has been established and the property app-title stands for the name of application
   private static final MainFrame frame = MainFrame.getMainFrame();

   public static void showWarningMsg(String msg){
      JOptionPane.showMessageDialog(frame,msg,appTitle,JOptionPane.WARNING_MESSAGE);
   }
   public static void showErrMsg(String msg){
       JOptionPane.showMessageDialog(frame,msg,appTitle,JOptionPane.Error_MESSAGE);
   }
   public static int showConfirmMsg(String msg){
        return JOptionPane.showConfirmDialog(frame,msg,appTitle,JOptionPane.YES_NO_OPTON,JOptionPane.QUESTION_MESSAGE);
   }
}

public class PropertyReader{
   private static Properties property = null;
  
   static{
      InputSteam stream = null;
      try{
        stream=PropertyReader.class.getResourceAsStream("/resource/properties.properties");
        property = new Properties();
        property.load(stream);
      }catch(IOException e){
          e.printStackTrace();
      }finally{
          if(stream != null){
             try{
                stream.close();
             }catch(IOException e){
                e.printStackTrace();
             }           
          }
      }
   }
   public static String getResource(String key){
     if(property == null){
       return null;// init error;
     }
     
     return property.getProperty(key);
   }
}

第三步，输入启动类。输入带有 main 方法的类名

/**
 * @(#)Hello.java
 * 没有main方法，输出Hello,World!
 * 本程序请直接用javac编译，java解释运行
 * 经测试，如果在Eclipse中试图运行，默认情况下，会启动失败
 *
 * @version J2SDK 1.4.2_10-b03
 */
public class Hello {
 static {
  System.out.println("Hello,World!");
  System.exit(0);  //!如果缺少这一句，会出现运行期异常
 }
}

    假使我们为Hello类增加一个main方法，虽然它也是static的，但是静态初始化块会在main之前被执行。

    二、如果您想了解更多的细节，请查看如下的资料：

    1．有关Robocode的详细资料，请查看如下的pdf文档，内含Robocode的详细介绍、Robocode安装、高水平机器人的代码分析、高级瞄 准策略、Robocode内核分析等7篇文章，帮助你入门，全部资料来自《程序员》2003年合订本配套光盘，请点击这里：http://www.loujing.com/mywork/java/Robocode/RobocodeBrief.pdf，(首先请确保你计算机内安装了pdf文档阅读器，可自Adobe的网站自由下载，http://www.chinese-s.adobe.com/products/acrobat/readstep2.html)。

    2．如果您需要了解Robocode更详细的信息，可参看如下网站：
    Robocode在IBM的官方网站为：http://www.alphaworks.ibm.com/tech/robocode；另外，现在Robocode项目已经终止，成为开源项目，您可以从如下站点下载其源代码：http://robocode.sourceforge.net/。

    3．您可以自我的网站下载Robocode的1.0.6版本，下载地址为：http://www.loujing.com/mywork/java/Robocode/Robocode.rar，下载解压后双击其中的install.bat即可安装。当然，请首先确保您的机器里安装了J2SE SDK(Java软件开发包)，如果您不知道如何设置Java运行环境，请参考本人的另一篇文章：ShowArticle.asp?ArticleID=31。

    4．如果您是在Eclipse里进行Robocode的开发，您可以参考我的这篇文章http://www.loujing.com/Article/ShowArticle.asp?ArticleID=33。

import java.util.*;

一，JBuilder光标定位不准确的修改:: 

在中文的Windows下面安装JBuilder后，
在IDE的代码编辑器里面光标定位会不准确，
很多人通过修改Editor的缺省字体来修改这个问题，
但是JBuilder预设的字体是最美观的。鱼与熊掌不能兼得，那么改怎么办才好呢？

其实最简单的办法就是把JBuilder的Editor里面的
缺省字体里面的语法高亮列表里面"Reserved word"的Bold的属性去掉，
就可以了，而且字体还更漂亮！

具体路径："Editor Option"->"Color"->"Screen Element"->"Reserved word"
->"Attributes"->"Bold"，把"Bold"uncheck就可以了！

Enjoy it！！
二，如何在Jbuilder中使用自定义的Server.xml文件？
这个问题相信困扰很多人了，解决办法如下
1，在jbuilder中运行web app
2,在输出窗口察看server0808的输出目录
我的jbuilder7是C:/myapp/Tomcat/conf/server8080.xml
3,把这个文件备份，
其中有这样一行

4，删除这一行，停止web app
5,此时Tomcat目录下没有conf目录了，建立这个目录，将删除了3中这句话的文件放在
conf目录，还叫做server8080.xml，把自己需要的连接池等信息加入

6，运行web app，我在jbuilder7中不会替换这个文件。

ok...........................

Using a Custom server.xml file with Tomcat in JBuilder
Question:  How do a use a custom server.xml with Tomcat in JBuilder 4,5 and 6?

Answer:
Make a copy of the JBuilder-generated server.xml file while your Web app
is running, modify the line which says the file was generated by JBuilder,
make you mods, and then AFTER you quit the Web app you were just running,
save your modified copy back to server.xml. After that, JBuilder won't
modify that file.

Note: Remember that when you shut down Tomcat you'll need to recreate
the directory that the server.xml file was in before you can save it back out.
After you've made the above modifications, JBuilder will leave the directory
alone.
 
三，如何修改jbuilderx的字体
#1: 安装JBX
#2: 改变一下，Editor|Display 里面的字体，主要是让jbx搜索系统字体
#3: 关闭JBX
#4: 用户主目录下（我的是：C:\Documents and Settings\Administrator\）
.primetimeX/user_zh.properties

添加一行：
editor.display;fixed_fonts.3=\u5b8b\u4f53

就可以啦！
同样也可以添加其它字体，只要在
editor.display;known_fonts
列表中有的，都可以添加，顺序编号就行了

package temps;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

/**
* Title:
*
* Description:
*
* Copyright: Copyright (c) 2005
*
* Company:
*
* @author not attributable
* @version 1.0
*/
public class TestMIDlet extends MIDlet
{
private Display display;

public void startApp()
{
try
{
display = Display.getDisplay(this);
Displayable1 gameCanvas = new Displayable1();
gameCanvas.start();
display.setCurrent(gameCanvas);
}
catch (Exception ex)
{
System.out.println(ex);
}
}

public Display getDisplay()
{
return display;
}

public void pauseApp()
{
}

public void destroyApp(boolean unconditional)
{
exit();
}

public void exit()
{
System.gc();
destroyApp(false);
notifyDestroyed();
}
}

package temps;

import javax.microedition.lcdui.*;
import java.util.Random;
import javax.microedition.lcdui.game.*;
/**
* Title:
*
* Description:
*
* Copyright: Copyright (c) 2005
*
* Company:
*
* @author not attributable
* @version 1.0
*/
public class Displayable1 extends GameCanvas implements Runnable
{
private boolean isPlay; // Game Loop runs when isPlay is true
private long delay; // To give thread consistency
private int currentX, currentY; // To hold current position of the 'X'
private int width; // To hold screen width
private int height; // To hold screen height
private Random random=new Random(System.currentTimeMillis());
private final int[] sequence={0,1,2,1,0,1,2,1,0,1,2,1,1,1,1,1,1};
private int counter=0;
private int enemyX,enemyY;
private int enemyDirect=0;
private boolean isdown=false;

private boolean isalive=true;

// Sprites to be used
private Sprite playerSprite;
private Sprite backgroundSprite;
private Sprite enemySprite;

// Layer Manager
private LayerManager layerManager;

// Constructor and initialization
public Displayable1() throws Exception
{
super(true);
width = getWidth();
height = getHeight();

currentX = width / 2;
currentY = height / 2;
enemyX=width/4;
enemyY=height/4;
delay = 100;

Image playerImage=null;
Image backgroundImage=null;
Image enemy=null;
// Load Images to Sprites
try
{
playerImage = Image.createImage("/transparent.png");
backgroundImage = Image.createImage("/background.png");
enemy=Image.createImage("/frames.png");
}
catch(Exception e)
{
System.out.println("get Image error!"+e.getMessage());
}

playerSprite = new Sprite(playerImage, 32, 32);
System.out.println(playerSprite.getRawFrameCount());
enemySprite=new Sprite(enemy,50,21);
backgroundSprite = new Sprite(backgroundImage);
layerManager = new LayerManager();
layerManager.append(playerSprite);
layerManager.append(enemySprite);
layerManager.append(backgroundSprite);

}

// Automatically start thread for game loop
public void start()
{
isPlay = true;
Thread t = new Thread(this);
t.start();
}

public void stop()
{
isPlay = false;
}

// Main Game Loop
public void run()
{
Graphics g = getGraphics();
while (isPlay == true)
{
input();
drawScreen(g);
try
{
Thread.sleep(delay);
}
catch (InterruptedException ie)
{

}
}
}

// Method to Handle User Inputs
private void input()
{
int keyStates = getKeyStates();

playerSprite.setFrame(0);
if(isalive)
{
if(counter==0)
{
enemyDirect=Math.abs(random.nextInt()%4);
}
counter++;
switch(enemyDirect)
{
case 0:
enemyY=Math.max(0,--enemyY);
break;
case 1:
enemyY=Math.min(++enemyY,height-enemySprite.getHeight());
break;
case 2:
enemyX=Math.max(0,--enemyX);
break;
case 3:
enemyX=Math.min(++enemyX,width-enemySprite.getWidth());
break;
}
counter=(counter++)%(sequence.length());
enemySprite.setFrame(sequence[counter]);
}
else
{
enemyY+=counter;
enemyY=Math.min(enemyY,height-enemySprite.getHeight());

if(enemyY
counter++;
enemySprite.setFrame(3);
}

// Left
if ((keyStates & LEFT_PRESSED) != 0)
{
currentX = Math.max(0, currentX - 1);
playerSprite.setFrame(1);
}

// Right
if ((keyStates & RIGHT_PRESSED) != 0)
if (currentX + 5 < width)
{
currentX = Math.min(width, currentX + 1);
playerSprite.setFrame(3);
}

// Up
if ((keyStates & UP_PRESSED) != 0)
{
currentY = Math.max(0, currentY - 1);
playerSprite.setFrame(2);
}

// Down
if ((keyStates & DOWN_PRESSED) != 0)
{
isdown=true;
}

if ((keyStates & DOWN_PRESSED) != 0)
{
if(isdown)
{
if (currentY + 10 < height)
{
currentY = Math.min(height, currentY + 1);
playerSprite.setFrame(4);
}
}
}

if((keyStates & FIRE_PRESSED)!=0)
{
isalive=!isalive;
counter=0;
}

if(!(enemyX+enemySprite.getWidth()currentX+playerSprite.getWidth() || enemyY>currentY+playerSprite.getHeight()) && isalive)
{
counter=0;
isalive=false;
}
}

// Method to Display Graphics
private void drawScreen(Graphics g)
{
g.setColor(0xffffff);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(0x0000ff);

// updating player sprite position
playerSprite.setPosition(currentX, currentY);
enemySprite.setPosition(enemyX,enemyY);

layerManager.setViewWindow(0, 0, width, height);
layerManager.paint(g, 0,0);

g.setColor(0xffffff);
flushGraphics();
}

}