JavaMe连载(7)-数据永久存储 (一)

【问题描述】JavaMe不支持关系型数据库的操作，如何实现永久存储呢？

JavaMe中，之所以没有不支持数据库，是因为功能性手机一般存储空间较小。所以采用一种成为“记录”的概念代替，即采用一种成为RMS的机制进行永久存储。

【实例】

UserDataItem.java

[html] package com.token.model;

import com.token.util.StringDealMethod;

public class UserDataItem {
private int id;
public String name = null;
public String passwd = null;

public UserDataItem(String name,String passwd)
{
this.name = name;
this.passwd = passwd;
}

public UserDataItem(int id,byte[] data){
this.id=id;
String temp=new String(data);
String temp_sub[] = StringDealMethod.split(temp, ",");
this.name = temp_sub[0];
this.passwd = temp_sub[1];
}

public int getId(){
return id;
}

public void setId(int id){
this.id=id;
}

public String getName(){
return name;
}

public void setName(String name){
this.name = name;
}

public String getPasswd(){
return passwd;
}

public void setPasswd(String passwd){
this.passwd = passwd;
}

public byte[] getBytes(){
String temp=null;

if(name==null||passwd==null){
return null;
}else{
temp=name+","+passwd;
}

return temp.getBytes();
}
}
package com.token.model;

import com.token.util.StringDealMethod;

public class UserDataItem {
private int id;
public String name = null;
public String passwd = null;

public UserDataItem(String name,String passwd)
{
this.name = name;
this.passwd = passwd;
}

public UserDataItem(int id,byte[] data){
this.id=id;
String temp=new String(data);
String temp_sub[] = StringDealMethod.split(temp, ",");
this.name = temp_sub[0];
this.passwd = temp_sub[1];
}

public int getId(){
return id;
}

public void setId(int id){
this.id=id;
}

public String getName(){
return name;
}

public void setName(String name){
this.name = name;
}

public String getPasswd(){
return passwd;
}

public void setPasswd(String passwd){
this.passwd = passwd;
}

public byte[] getBytes(){
String temp=null;

if(name==null||passwd==null){
return null;
}else{
temp=name+","+passwd;
}

return temp.getBytes();
}
}

UserDataRecord.java

[html] package com.token.util;

import java.util.Vector;

import javax.microedition.rms.RecordComparator;
import javax.microedition.rms.RecordEnumeration;
import javax.microedition.rms.RecordStore;
import javax.microedition.rms.RecordStoreException;

import com.token.model.*;

public class UserDataRecord {
private static final String RECORDSTORE_NAME="USER_DB";
private static RecordStore info;

public UserDataRecord(){
}

//打开RecordStore，没有则创建
public void openDataBase() {
try {
info = RecordStore.openRecordStore(RECORDSTORE_NAME, true);
}catch (RecordStoreException ex) {
info =null;
}
}
//关闭RecordStore
public void closeDataBase() {
if (info!= null) {
try {
info.clos