rltest.java

J2ME开发实例,内含有可直接运行的源程序代码,供大家学习参考

//RLTest.java
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.io.*;
import javax.microedition.rms.* ;
public class RLTest extends MIDlet implements RecordListener
{
	private Display display;
	public RLTest()
	{
		display = Display.getDisplay(this);
	}
	public void startApp()
	{
		String dbname = "testdb" ;
		Form f = new Form("RS Test") ;
		RecordStore rs = openRSAnyway(dbname) ;
		rs.addRecordListener(this) ;
		if( rs == null )
		{
			f.append("Table open fail") ;
		}
		else
		{
			try
			{
				byte []data = new byte[2] ;
				data[0] = 15 ;
				data[1] = 16 ;
				int id = rs.addRecord(data,0,data.length) ;
				data[0] = 25 ;
				data[1] = 26 ;
				rs.setRecord(id,data,0,data.length) ;
				rs.deleteRecord(id) ;
				rs.addRecord(data,0,data.length) ;
				rs.closeRecordStore() ;
				deleteRS(dbname) ;
			}
			catch(Exception e)
			{ }
		}
		display.setCurrent(f) ;
	}
	public void pauseApp()
	{ }
	public void destroyApp(boolean unconditional)
	{ }
	public void recordAdded(RecordStore rs,int recordid)
	{
		try
		{
			byte []tmp = rs.getRecord(recordid) ;
			System.out.println("Record " + recordid + "is added.") ;
			System.out.println("Content=" + tmp[0] + tmp[1]) ;
		}
		catch(Exception e)
		{
			System.out.println(e.getMessage()) ;
		}
	}
	public void recordChanged(RecordStore rs,int recordid)
	{
		try
		{
			byte []tmp = rs.getRecord(recordid) ;
			System.out.println("Record " + recordid + "is changed.") ;
			System.out.println("Content=" + tmp[0] + tmp[1]) ;
		}
		catch(Exception e)
		{
			System.out.println(e.getMessage()) ;
		}
	}
	public void recordDeleted(RecordStore rs,int recordid)
	{
		try
		{
			//請勿在此使用byte []tmp = rs.getRecord(recordid) ;
			//因为此时记录已被刪除
			System.out.println("Record " + recordid + "is deleted.") ;
		}
		catch(Exception e)
		{
			System.out.println(e.getMessage()) ;
		}
	}
	public RecordStore openRSAnyway(String rsname)
	{
		RecordStore rs = null ;
		if(rsname.length() > 32)
			return null ;
		try
		{
			rs = RecordStore.openRecordStore(rsname,true) ;
			return rs ;
		}
		catch(Exception e)
		{
			return null ;
		}
	}
	public boolean deleteRS(String rsname)
	{
		if(rsname.length() > 32)
			return false ;
		try
		{
			RecordStore.deleteRecordStore(rsname) ;
		}
		catch(Exception e)
		{
			return false ;
		}
		return true ;
	}
}