recordidmidlet.java

java移动通信程序设计

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;
// A first MIDlet with simple text and a few commands.
public class RecordIDMIDlet extends MIDlet
implements CommandListener {
  private Command exitCommand;
    //The display for this MIDlet
  private Display display;

  public RecordIDMIDlet() {
    display = Display.getDisplay(this);
    exitCommand = new Command("离开", Command.EXIT, 1);
   }

  // Start the MIDlet by creating the TextBox and
  // associating the exit command and listener.
  public void startApp() {
	TextBox aTextBox = new TextBox("主画面",null,256,TextField.ANY);

	RecordStore rs = null;
	byte[] name =null;
	boolean existingOrNot = false;
	boolean OK = true;

	existingOrNot = existing("aRS");
	if(existingOrNot){
	   try{
		rs = RecordStore.openRecordStore("aRS",false);
            }
            catch(Exception e){
		OK = false;
	   }
	   finally{
		 if(OK){
			 aTextBox.setString("aRS已存在并且已打开");
	          }
	          else{
			aTextBox.setString("aRS已存在但无法打开");
	          }
            }
        }
        else{
	try{
		rs = RecordStore.openRecordStore("aRS",true);
	    }
             catch(Exception e){
		OK = false;
	    }
	    finally{
		if(OK){
	    	aTextBox.setString("aRS虽未存在，但已创建并完成打开的操作!");
		}
		else{
	    	aTextBox.setString("aRS虽未存在，但无法创建，打开文件失败!");
		}
	}
	}

    if(OK){
       try{
	    	for(int i=1;i<=3;i++){
		   	   name = ("JIDCA"+i).getBytes();
  			   rs.addRecord(name,0,name.length);
		    }
	   }
	   catch(Exception e){
			aTextBox.setString("新增记录的操作失败!");
	   }
       try{
		   rs.deleteRecord(1);
		   aTextBox.setString("recordID为1的记录已被删除");
	   }
	   catch(InvalidRecordIDException e){
		   try{
		       aTextBox.setString("目前共有" + rs.getNumRecords() +
		                          "笔记录,但找不到recordID为1的记录");
		   }
		   catch(RecordStoreNotOpenException rse){
		   }
	   }
	   catch(RecordStoreException e){  //针对deleteRecord
	   }
	   finally{
    	    try{
	    	   rs.closeRecordStore();
	        }
	        catch(Exception e){
            }
	   }
    }

    aTextBox.addCommand(exitCommand);
    aTextBox.setCommandListener(this);
    display.setCurrent(aTextBox);
  }

  // Pause is a no-op because there are no background
  // activities or record stores to be closed.
  public void pauseApp() { }

  // Destroy must cleanup everything not handled
  // by the garbage collector.
  // In this case there is nothing to cleanup.
  public void destroyApp(boolean unconditional) { }

  public boolean existing(String recordStoreName) {
    boolean existingOrNot = false;
    RecordStore rs = null;
    if(recordStoreName.length() > 32) return false;
    try{
    	rs = RecordStore.openRecordStore(recordStoreName,false);
    }
    catch(RecordStoreNotFoundException e){
        existingOrNot = false;
    }
    catch(Exception e){
    }
    finally{
    	try{
	        rs.closeRecordStore();
	    }
	    catch(Exception e){
	    }
    }
    return existingOrNot;
  }

  public void commandAction(Command c, Displayable s) {
     destroyApp(false);
      notifyDestroyed();
  }
}