rmsdemomidp.java

这是我在用J2ME Wireless Toolkit编写的一个手机存储功能

//import the 3 packages here
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;

public class RmsDemoMidp extends MIDlet implements CommandListener {

    //Declaration of Variables
     TextBox textBox = new TextBox ("Diary", "", 150, TextField.ANY);
    int currentId = 1;


byte[] myBytes;
String entry;


    
     //Declare the text area for writing the events for the diary
     //Declare the diary to be used for storing the events.
    RecordStore diary;
    
    Display display;
    
    //Declare the commands for the menu
    static final Command prevCommand = new Command ("Prev", Command.SCREEN, 1);
    static final Command nextCommand = new Command ("Next", Command.SCREEN, 2);
    static final Command newCommand = new Command ("New", Command.SCREEN, 3);
    static final Command deleteCommand = new Command ("Delete", Command.SCREEN, 4);
    static final Command exitCommand = new Command ("Exit", Command.SCREEN, 5);


    public RmsDemoMidp ()
   {	
	//Setup the diary for strong records, use try statement
	try {
	    diary = RecordStore.openRecordStore ("diary", true);
	    String text = loadEntry (diary.getNumRecords ());
	    textBox.setString (text);
	    textBox.setTitle ("MyDiary - Day " + currentId);
	   myBytes = new byte(diary.getRecordSize(currentId) );
	}
    catch (RecordStoreException e)
        {
	    throw new RuntimeException ("Cannot open diary; reason: "+e);
	}
	
	//add the commands to the text area
	textBox.addCommand (prevCommand);
	textBox.addCommand (nextCommand);
	textBox.addCommand (newCommand);
	textBox.addCommand (deleteCommand);
	textBox.addCommand (exitCommand);
	//set the command listener to listen to the commands
	textBox.setCommandListener (this);
    }




    public String loadEntry (int newId) throws RecordStoreException
   {
	   //check if it is a new entry or the first entry to the diary, if it is, add a blank record to the diary

	 if(newId!=currentId) entry = diary.addRecord(myBytes,0,30);

		
	  //else, get the record entry
	else if(newId==currentId) entry = diary.getRecord(newId);

	  //Replace the return here with an entry from the diary for the current record
	return (null);
    }


    public void saveEntry (String entry) throws RecordStoreException
   {
	//save the new entry to the diary
	diary.setRecord(currentId,myBytes,0,30);

    }

    public void startApp ()
   {
	//initialise current display
	display = Display.getDisplay (this);
	display.setCurrent (textBox);
   }

    public void destroyApp (boolean unconditional)
   {
	try
	{
	    String text;
	    text = textBox.getString ();
	    saveEntry (text);
	    diary.closeRecordStore ();
	}
	catch (RecordStoreException e)
	{
	    throw new RuntimeException ("Cannot close Diary; reason: "+e);
	}
    }

    public void pauseApp ()
    {
    }

    public void commandAction (Command c, Displayable d)  
    {try{
	if(c==deleteCommand)
		{
		 destroyApp(true);
		 notifyDestroyed();
		}
	 else if(c==prevCommand)
		{currentId-=1;
		 entry = diary.getRecord(currentId);
		}
	 else if(c==nextCommand)
		{currentId+=1;
		entry = diary.getRecord(currentId);
		}
	 else if(c==newCommand)
		{currentId+=1;
		String text = loadEntry (diary.getNumRecords ());
	    textBox.setString (text);
	    textBox.setTitle ("MyDiary - Day " + currentId);
	display = Display.getDisplay (this);
	display.setCurrent (textBox);
		}
	 else if(c==exitCommand)
		{
		 destroyApp(true);
		 notifyDestroyed();
		}
	}
	catch(RecordStoreNotOpenException e){} 
	catch(InvalidRecordIDException ie){}
	catch(RecordStoreException re){}

    }
}