recordenumerationexample.java

rms常用操作例子,可通过这些例子修改成你想要的代码,绝对有用!

import javax.microedition.rms.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
 
public class RecordEnumerationExample extends MIDlet{
  private RecordStore recStore = null;
  static final String REC_STORE = "test_db";
 
  public RecordEnumerationExample()  {
    openRecStore();   // Create the Record Store
    
    // Write a few records
    writeRecord("CoreJ2ME");
    writeRecord("In the middle");    
    writeRecord("MicroJava");        
    
    System.out.println("------------------------------");                            
    readRecords();
 
    System.out.println("------------------------------");                                
    deleteRecord(2);
 
    // This read method will throw an error
    // readRecords();
 
    // New and improved read using Enumeration
    readRecordsUpdate();    
    closeRecStore(); 
  }
 
  public void destroyApp( boolean unconditional ){}
 
  public void startApp(){
    // There is no user interface, go ahead and shutdown
    destroyApp(false);
    notifyDestroyed();
  }
 
  public void pauseApp(){}
 
  public void openRecStore(){
    try{
      // The second parameter indicates that the Record Store
      // should be created if it does not exist
      recStore = RecordStore.openRecordStore(REC_STORE, true );
    }
    catch (Exception e){
      System.err.println(e.toString());
    }
  }    
  
  public void closeRecStore(){
    try{
      recStore.closeRecordStore();
    }
    catch (Exception e){
      System.err.println(e.toString());
    }
  }
 
  public void writeRecord(String str){
    byte[] rec = str.getBytes();
 
    try{
      recStore.addRecord(rec, 0, rec.length);
      System.out.println("Writing record: " + str);
    }
    catch (Exception e){
      System.err.println(e.toString());
    }
  }
 
  public void readRecords(){
    try{
      // Intentionally small to test code below
      byte[] recData = new byte[5]; 
      int len;
 
      for (int i = 1; i <= recStore.getNumRecords(); i++)      
      {
        // Allocate more storage if necessary
        if (recStore.getRecordSize(i) > recData.length)
          recData = new byte[recStore.getRecordSize(i)];
       
        len = recStore.getRecord(i, recData, 0);
        System.out.println("Record ID#" + i + ": " + 
                            new String(recData, 0, len));
      }
    }
    catch (Exception e)
    {
      System.err.println(e.toString());
    }
  }  
 
  public void readRecordsUpdate()
  {
    try
    {
      System.out.println("Number of records: " + recStore.getNumRecords());
      
      if (recStore.getNumRecords() > 0)
      {
        RecordEnumeration re = recStore.enumerateRecords((RecordFilter)null, 
			                                             (RecordComparator)null, false);
        while (re.hasNextElement())
        {
          String str = new String(re.nextRecord());
          System.out.println("Record: " + str);          
        }
      }
    }
    catch (Exception e)
    {
      System.err.println(e.toString());
    }
  }
  
  public void deleteRecord(int id)
  {
    try
    {
      recStore.deleteRecord(id);
    }
    catch (Exception e)
    {
      System.err.println(e.toString());
    }
  }
}