更新记录存储区j2me中的记录

问题描述

| 我想知道用于更新j2me记录存储中记录的方法。谢谢....     

解决方法

只需使用

RecordStore.setRecord()

    ,尝试这个

Preferences preferences  = new Preferences(\"ChatAppPref\");
preferences.put(\"login\",\"y\");
preferences.save();
String pIsLogin  = preferences.get(\"login\");

首选项类在这里

package com.util;
import java.util.*;
import javax.microedition.rms.*;

public class Preferences {
  private String mRecordStoreName;

  private Hashtable mHashtable;

  public Preferences(String recordStoreName)
      throws RecordStoreException {
    mRecordStoreName = recordStoreName;
    mHashtable = new Hashtable();
    load();
  }

  public String get(String key) {
    return (String)mHashtable.get(key);
  }

  public void put(String key,String value) {
    if (value == null) value = \"\";
    mHashtable.put(key,value);
  }

  private void load() throws RecordStoreException {
    RecordStore rs = null;
    RecordEnumeration re = null;

    try {
      rs = RecordStore.openRecordStore(mRecordStoreName,true);
      re = rs.enumerateRecords(null,null,false);
      while (re.hasNextElement()) {
        byte[] raw = re.nextRecord();
        String pref = new String(raw);
        // Parse out the name.
        int index = pref.indexOf(\'|\');
        String name = pref.substring(0,index);
        String value = pref.substring(index + 1);
        put(name,value);
      }
    }
    finally {
      if (re != null) re.destroy();
      if (rs != null) rs.closeRecordStore();
    }
  }

  public void save() throws RecordStoreException {
    RecordStore rs = null;
    RecordEnumeration re = null;
    try {
      rs = RecordStore.openRecordStore(mRecordStoreName,false);

      // First remove all records,a little clumsy.
      while (re.hasNextElement()) {
        int id = re.nextRecordId();
        rs.deleteRecord(id);
      }

      // Now save the preferences records.
      Enumeration keys = mHashtable.keys();
      while (keys.hasMoreElements()) {
        String key = (String)keys.nextElement();
        String value = get(key);
        String pref = key + \"|\" + value;
        byte[] raw = pref.getBytes();
        rs.addRecord(raw,raw.length);
      }
    }
    finally {
      if (re != null) re.destroy();
      if (rs != null) rs.closeRecordStore();
    }
  }
}