dbdemo.java

J2ME MIDP 2.0 无线设备编程的一些源码

//dbDemo.java file
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

public class dbDemo extends MIDlet implements CommandListener
{
    //命令对象
    private Command exitCommand, createCmd, delCmd, ocCmd, ckCmd;
    private TextBox tb; //通过TextBox来显示信息
    private UsersRecordStore userRec; //数据操作对象
    public dbDemo()
    {
        tb =new TextBox("OutputWindow","",120,TextField.ANY);
        exitCommand =new Command("Exit",Command.EXIT,1);
        createCmd =new Command("CreateDb",Command.SCREEN,1);
        delCmd =new Command("DelDb",Command.SCREEN,1);
        ocCmd =new Command("Open&Close",Command.SCREEN,1);
        ckCmd =new Command("IsExist",Command.SCREEN,1);
        tb.addCommand(exitCommand);
        tb.addCommand(createCmd);
        tb.addCommand(delCmd);
        tb.addCommand(ocCmd);
        tb.addCommand(ckCmd);
        tb.setCommandListener(this);
        userRec = new UsersRecordStore(Display.getDisplay(this));
    }
    protected void startApp(  ) throws MIDletStateChangeException
    {
        Display.getDisplay(this).setCurrent(tb);
    }

    protected void pauseApp(  )
    {
    }

    protected void destroyApp( boolean p1 )
    {
    	userRec.CloseDb();
    }

    public void commandAction(Command c,Displayable d)
    {
        if (c ==exitCommand)
        {
            destroyApp(false);
            notifyDestroyed();
        }
        else if(c ==createCmd)
        {
            if( userRec.CreateDb())
                tb.setString("Create db OK");
            else
                tb.setString("Create db failed");
            
        }
        else if(c ==delCmd)
        {
            if(userRec.DeleteDb() )
                tb.setString("Delete db OK");
            else
                tb.setString("Delete db failed");
        }
        else if(c ==ocCmd)
        {
            if( userRec.OpenDb() )
            {
                if( userRec.CloseDb())
                    tb.setString("Open db OK & Close db OK");
                else
                    tb.setString("Open db OK & Close db failed");
            }
            else
                tb.setString("Open db failed");
        }
        else if(c ==ckCmd)
        {
            if( userRec.IsDbExist() )
                tb.setString("Db is exist");
            else
                tb.setString("Db is NOT exist");
        }
    }
}