usersrecordstore.java

J2ME MIDP 2.0 无线设备编程的一些源码

import java.util.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;

public class UsersRecordStore 
{
    public final String recName="chap8db"; //记录文件名称
    public RecordStore rec=null; //保存记录文件对象
    protected Alert alert; //用于显示异常时的错误信息
    protected Display display;
    public UsersRecordStore(Display dis)
    {
        display = dis;
        alert = new Alert("RMS error !");
        alert.setTimeout(5000);
    }
    //显示错误信息
    protected void ShowError(Exception e)
    {//通过警告窗口显示错误信息
        alert.setString(e.toString());
        display.setCurrent(alert, display.getCurrent());
    }
    //v0.1 功能 记录文件的 打开，关闭，创建，删除
    //检测记录文件是否存在
    public boolean IsDbExist()
    {
        try
        {//打开然后关闭记录文件，通过异常类型来判断记录文件是否存在
            RecordStore rs = RecordStore.openRecordStore(recName, false);
            rs.closeRecordStore();
            rs=null;
        }
        catch(RecordStoreFullException e1)
        {
            return true;
        }
        catch(RecordStoreNotFoundException e2)
        {//捕捉到记录不存在的错误，表示记录文件不存在
            return false;
        }
        catch(RecordStoreException e3)
        {
            ShowError(e3);
        }
        return true;
    }
    //打开记录文件
    public boolean OpenDb()
    {
        try
        {
            rec = RecordStore.openRecordStore(recName, false);
            //打开文件后检测文件的最后修改时间，在正式版本中可以删除
            Calendar cal = Calendar.getInstance();
            cal.setTime(new Date(rec.getLastModified()));
            System.out.println("LastModified = " + cal.toString() );
            
            //检查空间
            System.out.println("getSize = "+ rec.getSize());
            System.out.println("getSizeAvailable = " + rec.getSizeAvailable() );
            return true;
        }
        catch(Exception e)
        {
            ShowError(e);
        }
        return false;
    }
    //关闭记录文件
    public boolean CloseDb()
    {
        if(rec != null)
        {
            try
            {
                rec.closeRecordStore();
                rec = null;
                return true;
            }
            catch(Exception e)
            {
                ShowError(e);
            }
        }
        return false;
    }
    //创建记录文件
    public boolean CreateDb()
    {//创建文件前请先检查记录文件是否已经存在
        try
        {//通过打开记录文件的方式来进行创建
            RecordStore rs = RecordStore.openRecordStore(recName, true);
            rs.closeRecordStore();
            rs=null;
            return true;
        }
        catch(Exception e)
        {
            ShowError(e);
        }
        return false;
    }
    //删除记录文件
    public boolean DeleteDb()
    {//删除文件前请先检查记录文件是否已经存在
        try
        {
            RecordStore.deleteRecordStore(recName);
            return true;
        }
        catch(Exception e)
        {
            ShowError(e);
        }
        return false;
    }
    //v0.2功能 记录的添加，删除，更新，创建结果集合
    //增加记录
    public int AddRecord(String name,String sex,String birth,String email)
    {//返回被增加的记录号，返回-1 表示出错
        String buffer = name + "&" + sex + "&" + birth + "&" + email;
        byte[ ] data = buffer.getBytes();
        int recId = -1;
        try
        {
            recId = rec.addRecord(data,0, data.length);
        }
        catch (Exception e)
        {
            ShowError(e);
        }
        return recId ;
    }
    //删除记录
    public boolean DelRecord(int recId)
    {
        try
        {
            rec.deleteRecord(recId);
        }
        catch (Exception e)
        {
            ShowError(e);
            return false;
        }
        return true;
    }
    //更新记录
    public boolean UpdateRecord(int recId,String name,String sex,String birth,String email)
    {
        String buffer = name + "&" + sex + "&" + birth + "&" + email;
        byte[ ] data = buffer.getBytes();
        try
        {
            rec.setRecord(recId, data,0, data.length);
        }
        catch (Exception e)
        {
            ShowError(e);
            return false;
        }
        return true ;
    }
    //打开所有包含所有记录的结果集
    public RecordEnumeration OpenAllRecord(boolean autoUpdate)
    {
        RecordEnumeration enum = null;
        try
        {
            enum = rec.enumerateRecords(null, null, autoUpdate);
        }
        catch (Exception e)
        {
            ShowError(e);
        }
        return enum;
    }
    //通过记录号得到记录内容
    public byte[] getRecord(int recId)
        throws RecordStoreNotOpenException, InvalidRecordIDException, RecordStoreException
    {
        return rec.getRecord(recId);
    }
    //v0.3功能 查找记录，对记录进行排序
    //查找指定姓名的用户
    public RecordEnumeration FindRecord(String name)
    {
        RecordEnumeration enum = null;
        try
        {
            UserFindFilter filter = new UserFindFilter(UserFindFilter.FULLMATCH,name);
            enum = rec.enumerateRecords(filter, null, false);
        }
        catch (Exception e)
        {
            ShowError(e);
        }
        return enum;
    }
    //创建按照姓名排序的结果集
    public RecordEnumeration SortRecordByName()
    {
        RecordEnumeration enum = null;
        try
        {
            UserSorter sorter = new UserSorter(UserSorter.SORTBYNAME);
            enum = rec.enumerateRecords(null, sorter, false);
        }
        catch (Exception e)
        {
            ShowError(e);
        }
        return enum;
    }
}