对我来说算是挑战性的一个J2ME数据存储的问题,高手请进！

老猫的TOM 2010-12-31 11:13:09
一直在做J2EE的开发，最近公司拉了一个J2ME手持机<PDA>（其实和手机差不多）开发项目，本人算是第一次做这样的项目，如果问题问的有些弱还希望高手不要见笑。
下面开始说问题：
PAD使用的是WTK平台，要实现的功能是：对数据进行保存、修改、删除、查询，由于环境的问题，程序要求在无网络的情况下能够正常运行，所以运行环境算是单机版的。
数据格式很简单包含：档案ID、卡号、用户名、金额。
数据量最少在一万条以上，由于只能存储在本机环境内，这对于手持机来说不是件容易的事情。起先准备使用操作本地文本文件的方式存储（txt文件，每一行为一条数据）但是j2me对文本文件的操作真是太低级。对于查询和修改数据不易操作，而且数据过大会导致内存溢出。
所以本人准备尝试使用嵌入式数据库来完成，目前选用的数据库位JMESQL,网上对于这个数据库的操作知识并不是很多，只能在官方找到所谓的例子，可是操作中创建表一直不成功。后台打印异常为：
开始创建表----

..............false

开始创建表----

br.com.dreamsource.mobile.jmesql.exceptions.SQLException: already exists: PRICETABLE -- S0001 in statement [CREATE TABLE priceTable (   id int identity,    name varchar(20) not null,    percent float not null,   primary key(id))] -- Table

	at br.com.dreamsource.mobile.jmesql.jdbcResultSet.<init>(+37)

	at br.com.dreamsource.mobile.jmesql.jdbcConnection.executeStandalone(+19)

	at br.com.dreamsource.mobile.jmesql.jdbcConnection.execute(+21)

	at br.com.dreamsource.mobile.jmesql.jdbcStatement.fetchResult(+36)

	at br.com.dreamsource.mobile.jmesql.jdbcStatement.execute(+5)

	at com.sqlplus.FrameMainMIDlet.createDatabase(+48)

	at com.sqlplus.FrameMainMIDlet.commandAction(+33)

	at javax.microedition.lcdui.Display$DisplayAccessor.commandAction(+282)

	at javax.microedition.lcdui.Display$DisplayManagerImpl.commandAction(+10)

	at com.sun.midp.lcdui.DefaultEventHandler.commandEvent(+68)

	at com.sun.midp.lcdui.AutomatedEventHandler.commandEvent(+47)

	at com.sun.midp.lcdui.DefaultEventHandler$QueuedEventHandler.handleVmEvent(+186)

	at com.sun.midp.lcdui.DefaultEventHandler$QueuedEventHandler.run(+57)

看字面意思是提示数据表已存在，但是我明明是第一次创建。
附上源码希望高手能帮忙看看：



package com.sqlplus;



import java.util.Vector;



import javax.microedition.lcdui.Command;

import javax.microedition.lcdui.CommandListener;

import javax.microedition.lcdui.Display;

import javax.microedition.lcdui.Displayable;

import javax.microedition.lcdui.Form;

import javax.microedition.lcdui.TextField;

import javax.microedition.midlet.MIDlet;

import javax.microedition.midlet.MIDletStateChangeException;



import br.com.dreamsource.mobile.jmesql.jdbcConnection;

import br.com.dreamsource.mobile.jmesql.jdbcDriver;

import br.com.dreamsource.mobile.jmesql.jdbcPreparedStatement;

import br.com.dreamsource.mobile.jmesql.jdbcResultSet;

import br.com.dreamsource.mobile.jmesql.jdbcStatement;

import br.com.dreamsource.mobile.jmesql.exceptions.SQLException;





public class FrameMainMIDlet extends MIDlet implements CommandListener {



	private Form mainForm;

	



	private static DatabaseManager myDatabaseManager;

	private UserPOJO userPOJO;



	TextField tf = new TextField("要写入的数据", "", 100, TextField.ANY);



	TextField cx = new TextField("查询条件", "", 100, TextField.ANY);



	TextField cxjg = new TextField("查询结果", "", 100, TextField.ANY);



	Command a_cmdSet = new Command("添加", Command.SCREEN, 0);



	Command w_cmdSet = new Command("修改", Command.SCREEN, 0);



	Command r_cmdSet = new Command("查询", Command.SCREEN, 0);

	

	Command c_cmdSet = new Command("创建表", Command.SCREEN, 0);



	Command exitCommand = new Command("退出", Command.EXIT, 0);



	public FrameMainMIDlet() {



		mainForm = new Form("嵌入式数据库");

		mainForm.append(tf);

		mainForm.append(cx);

		mainForm.append(cxjg);

		mainForm.addCommand(exitCommand);

		mainForm.addCommand(c_cmdSet);

		mainForm.addCommand(r_cmdSet);

		mainForm.addCommand(w_cmdSet);

		mainForm.addCommand(a_cmdSet);

		mainForm.setCommandListener(this);



	}



/*	*//**

	 * 检查数据库如果没有开始创建

	 * 

	 * @return

	 * @throws Exception

	 */



      public  void createDatabase(UserPOJO userPOJO) {

	        jdbcDriver driver = new jdbcDriver();

	        

	      //  String userName = userPOJO.getUserName();

	       // String userPassword = userPOJO.getPasswd();

	        

	        userPOJO.setUserName("SA");

	        userPOJO.setPasswd("");

	        userPOJO.setDbName(Consts.DATABASE_NAME);

	        

	        jdbcConnection connection;

			try {

				connection = driver.connect(userPOJO.getAsProperties());

				  jdbcStatement statement = connection.createStatement();

			        boolean l=statement.execute(Consts.CREATE_PRICETABLE_TBL);

			        System.out.println(".............."+l);

			        if(l==true){

			        

			        	tf.setString("创建表成功.........");

			        	

			        	 boolean k=statement.execute("insert into priceTable values (null, 'tabela1', 10)");

			        	 if(k==true){

			        		 

			        		 cx.setString("插入数据成功.......");

			        		 

			        		 try {

			        			 

			        			   jdbcPreparedStatement prepared =connection.prepareStatement("select name from priceTable");

			        			   jdbcResultSet res = prepared.executeQuery();

			        				

			        				int i;

			        				StringBuffer Results = new StringBuffer();

			        				this.cxjg.setString("");

			        				System.out.println("数据查询"+Results);

			        				if (!(res == null)) {

			        					while (res.next()) {

			        						for (i = 1; i <= res.getColumnCount(); i++) {

			        							this.cxjg.setString(this.cxjg.getString()

			        									+ res.getColumnName(i) + " -- "

			        									+ res.getString(i) + "\n");

			        						}

			        						this.cxjg.setString(this.cxjg.getString());

			        					}

			        				}

			        			} catch (Exception e) {

			        				this.cxjg.setString(e.getMessage());

			        			}

			        	 }else{

			        		 

			        		 cx.setString("插入数据失败......."); 

			        		 

			        	 }

			        	

			        	

			        }else{

			        	

			        	tf.setString("创建表失败.....");

			        	

			        }

			       // boolean i=statement.execute(Consts.CREATE_CUSTOMER_TBL);

			       

			       

			} catch (SQLException e1) {

				// TODO 自动生成 catch 块

				e1.printStackTrace();

			}

	      

	    }



	protected void destroyApp(boolean arg0) throws MIDletStateChangeException {

		// TODO 自动生成方法存根



	}



	protected void pauseApp() {

		// TODO 自动生成方法存根



	}



	protected void startApp() throws MIDletStateChangeException {

		// TODO 自动生成方法存根

		

		

		

		    this.userPOJO = new UserPOJO();

	        this.userPOJO.setConnectionURL(Consts.DATABASE_CONNETION_STRING);

	        this.userPOJO.setDbName(Consts.DATABASE_NAME);

	        if (DatabaseManager.databaseExists(Consts.DATABASE_NAME)) {

	        	Display.getDisplay(this).setCurrent(mainForm);

	        } else {

	        	Display.getDisplay(this).setCurrent(mainForm);

	        }



	}



	public void commandAction(Command command, Displayable displayable) {

		if (command == r_cmdSet) {

			

			



			



		}else if(command==c_cmdSet){

			System.out.println("开始创建表----");

			try {

				createDatabase( userPOJO);

			} catch (Exception e) {

				// TODO 自动生成 catch 块

				e.printStackTrace();

			}

			

		}



	}



}





package com.sqlplus;



import br.com.dreamsource.mobile.jmesql.io.Properties;



public class UserPOJO {





    private String userName;

    private String passwd;

    private String dbName;

    private String connectionURL;

            

    public UserPOJO() {

    }



    public String getUserName() {

        return userName;

    }



    public void setUserName(String userName) {

        this.userName = userName;

    }



    public String getPasswd() {

        return passwd;

    }



    public void setPasswd(String passwd) {

        this.passwd = passwd;

    }



    public String getDbName() {

        return dbName;

    }



    public void setDbName(String dbName) {

        this.dbName = dbName;

    }

    

    public String getConnectionURL() {

        return connectionURL;

    }



    public void setConnectionURL(String connectionURL) {

        this.connectionURL = connectionURL;

    }

    

    public Properties getAsProperties() {

        Properties p = new Properties();

        p.setProperty("user", this.userName);

        p.setProperty("password", this.passwd);

        p.setProperty("database", this.dbName);

        return p;

    }



}
...全文
263 8 打赏 收藏 转发到动态 举报
AI 作业
写回复
用AI写文章
8 条回复
切换为时间正序
请发表友善的回复…
发表回复
Manfeel 2011-07-06
  • 打赏
  • 举报
 回复
兄弟，我最近也在研究jMeSQL，现在碰到一个更头痛的问题，用insert插入的记录，退出程序后，记录消失。
我查了一下jMeSQL的文档（如果那也算是文档的话！），可能是创建的table默认都在memeory中，于是用
Create cached table,结果，insert数据直接抛异常，我发现是在Cache.java代码中，里面估计是存在某些bug，找了很久也没有结果，我的QQ:179813134，希望交流
老猫的TOM 2011-01-12
  • 打赏
  • 举报
 回复
本人循环插入数据，貌似达到七千五百行左右报内存溢出。
老猫的TOM 2011-01-12
  • 打赏
  • 举报
 回复
问题已解决，不是代码问题，本人也不知为何数据表创建成功返回的boolea值却是false，会不会是javamesql的一个bug？
kazeik 2011-01-11
  • 打赏
  • 举报
 回复
对数据库不了解.
老猫的TOM 2011-01-04
  • 打赏
  • 举报
 回复
谢谢上面的两位，但本人感觉很孤独，有没有其他高手进来看看
老猫的TOM 2010-12-31
  • 打赏
  • 举报
 回复 


package com.sqlplus;



public class Consts {



    public static final int UPDATE_TYPE_INSERT = 1;

    public static final int UPDATE_TYPE_UPDATE = 2;

    public static final int UPDATE_TYPE_DELETE = 3;

    

    public static final String DATABASE_NAME = "worders";

    public static final String DATABASE_CONNETION_STRING = "jdbc:mesqldb:worders";

    

    public static final String DROP_USER = "DROP USER ?";

    public static final String CREATE_USER = "CREATE USER ? PASSWORD ? admin";



    public static final String DROP_PRICTABLE_TBL = "DROP TABLE priceTable";

    public static final String CREATE_PRICETABLE_TBL = 

            "CREATE TABLE priceTable (" +

            "   id int identity, " +

            "   name varchar(20) not null, " +

            "   percent float not null," +

            "   primary key(id)" +

            ")";

    

    public static final String PRICETABLE_ID = "id";

    public static final String PRICETABLE_NAME = "name";

    public static final String PRICETABLE_PERCENT = "percent";

    

    public static final String PRICETABLE_SELECT_BY_EDIT = "SELECT * FROM pricetable";

    

    public static final String DROP_CUSTOMER_TBL = "DROP TABLE customer";

    public static final String CREATE_CUSTOMER_TBL = 

            "CREATE TABLE customer (" +

            "   id int identity," +

            "   remoteId int," +

            "   priceTableId  int," +

            "   dtRecord date," +

            "   name varchar(80) not null," +

            "   cpf varchar(11)," +

            "   cnpj varchar(14)," +

            "   phone varchar(10) not null," +

            "   fax varchar(10)," +

            "   contact varchar(80) not null," +

            "   mail varchar(80)," +

            "   zipCode varchar(8) not null," +

            "   credit float," +

            "   recordState int not null," +

            "   primary key(id)," +

            "   foreign key(priceTableId) references priceTable(id)" +

            ")";

    

    public static final String CUSTOMER_ID = "id"; 

    public static final String CUSTOMER_REMOTEID = "remoteid"; 

    public static final String CUSTOMER_PRICETABLEID = "pricetableid"; 

    public static final String CUSTOMER_DTRECORD = "dtrecord"; 

    public static final String CUSTOMER_NAME = "name"; 

    public static final String CUSTOMER_CPF = "cpf"; 

    public static final String CUSTOMER_CNPJ = "cnpj"; 

    public static final String CUSTOMER_PHONE = "phone"; 

    public static final String CUSTOMER_FAX = "fax"; 

    public static final String CUSTOMER_CONTACT = "contact"; 

    public static final String CUSTOMER_MAIL = "mail"; 

    public static final String CUSTOMER_ZIPCODE = "zipcode"; 

    public static final String CUSTOMER_CREDIT = "credit"; 

    public static final String CUSTOMER_RECORDSTATE = "recordstate"; 

    

    public static final String CUSTOMER_LOCATE_BY_FIELD = "SELECT id, name FROM customer";

    public static final String CUSTOMER_SELECT_BY_EDIT = 

            "SELECT priceTableId, name, cpf, cnpj, phone, fax, contact, mail, " +

            "zipCode, credit FROM customer";

    

    public static final String CUSTOMER_INSERT = 

            "INSERT INTO customer (remoteId, priceTableId, dtRecord, name, cpf, cnpj, phone, fax, " +

            "contact, mail, zipCode, credit, recordState) VALUES (0, ?, CURDATE(), ?, ?, ?, ?, ?, ?, ?, ?, ?, 0)";

    

    public static final String CUSTOMER_UPDATE = 

            "UPDATE customer set priceTableId = ?, name = ?, cpf = ?, cnpj = ?, phone = ?, fax = ?, " +

            "contact = ?, mail = ?, zipCode = ?, credit = ? where id = ?";

    

    public static final String CUSTOMER_DELETE = 

            "DELETE FROM customer where id = ?";

    

    

}


以上是我项目中的所有源码，如果大家对于存储还有其他什么好的方法或建议，麻烦能写出来参考一下，谢谢了。
softice_ 2010-12-31
  • 打赏
  • 举报
 回复
没搞过嵌入式数据库，帮顶
xiang1115 2010-12-31
  • 打赏
  • 举报
 回复
顶

我也正在研究jmesql，就是不知道怎么能创建表格。
J2ME
http://www.j2megame.org/index2.php?option=com_content&task=view&id=1256&pop=1 第一章：J2ME概述     * 介绍      这一章将开始教您使用 J2ME。我们将从定义 J2ME 开始，然后讨论它的总体架构并学习 J2ME 目标设备。作为架构讨论的一部分，我们将提供有关简表和配置的概述（后面
J2ME游戏优化秘密
本文章描述了代码优化在为移动设备写运行起来速度快的游戏中扮演的角色。我会用例子说明如何、什么时候和为什么要优化你的代码，来榨干兼容MIDP的手机的每一滴性能。我们将要讨论为什么优化是必要的和为什么有时候最好不要优化。我将解释高级优化和低级优化的差别，然后我们会知道如何使用J2ME无线开发包（WTK）自带的Profile程序来发现到哪里去优化你的代码。这篇文章最后揭示了很多让你的MIDlet运行的技
2005年毕业论文----J2ME手机游戏开发高计
一  前  言 1.1 摘要 J2ME(Java 2 Micro Edition) 是近年来随着各种不同设备，尤其是移动通信设备的飞速发展而诞生的一项新的开发技术。它定位在消费性电子产品的应用上，对设备的智能化、多样化，提供了革命性的解决方案，并因其“Write Once, run anywhere”的Java特性而提高开发的效率。 随着手机的日益普及、Java功能在移动设备上的实现，Java应用
J2ME很优秀的一篇文章
英文原文Java 2 Micro Edition and the World of Java1 IntroductionThe computer revolution of the 1970s increased the demand for sophisticated computersoftware to take advantage of the ever-increasing capacity of computers to process data.The C programming langua
J2ME

13,097

社区成员

26,492

社区内容

发帖
与我相关
我的任务
社区描述
Java J2ME
社区管理员
  • J2ME社区
加入社区
  • 近7日
  • 近30日
  • 至今

加载中

查看更多榜单
社区公告
暂无公告

试试用AI创作助手写篇文章吧

+ 用AI写文章