recordstoremidlet.java

十分简单的记录站操作

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;
import java.io.*;

public class RecordStoreMIDlet extends MIDlet {
	private RecordStore rs;
private String name;//玩家的姓名
private int record;//玩家的得分
private Display display;
public RecordStoreMIDlet() {
		super();
		display = Display.getDisplay(this);
	}
	protected void startApp() throws MIDletStateChangeException {
		record = 5000;//假设玩家本次得分是100分
		name = "playName";//玩家的姓名是"playName"
		String dbname = "dbName";
		Form f = new Form("RS Test");
		rs = openRSAnyway(dbname);
		if (rs == null) {
			f.append("Table open fail");
		} else {
			try {
				if (rs.getNextRecordID() == 1) {//如果rs中没有记录就增加一条数据
					add("player1", 80);
					f.append("rs中没有数据，增加本次的数据");
				} else {
					if (matches()) {
						if (save(name, record)) {
							f.append("本次修改数据成功！\n");
							f.append("修改数据为：\n");
							f.append("玩家姓名：" + name + "\n");
							f.append("得分是：" + record);
						}
					} else {
                       
                        f.append("本次得分为" + record + "\n");
						f.append("小于数据库中的分数，不覆盖rs中的数据");
					}
				}
				rs.closeRecordStore();
			} catch (Exception e) {
			}
		}
		display.setCurrent(f);
	}
protected void pauseApp() {
	}
protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
	}
public RecordStore openRSAnyway(String rsname) {
		RecordStore rs = null;
		//	名稱大於32 個字元就不接受
		if (rsname.length() > 32)
			return null;
		try {
			rs = RecordStore.openRecordStore(rsname, true);
			return rs;
		} catch (Exception e) {
			return null;
		}
	}
public boolean add(String playerName, int score) {//在rs中增加一条记录
		boolean ok = false;
		ByteArrayOutputStream bo = new ByteArrayOutputStream();
		DataOutputStream doSteam = new DataOutputStream(bo);
		try {
			doSteam.writeUTF(playerName);
			doSteam.writeInt(score);
			byte data[] = bo.toByteArray();
			rs.addRecord(data, 0, data.length);
			doSteam.close();
			ok = true;
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			ok = false;
		}
		return ok;
	}
public boolean matches() {//用本次玩家的分数和rs中的数据作比较
		boolean ok = false;
		try {
			byte[] data = rs.getRecord(1);
			DataInputStream doSteam = new DataInputStream(
					new ByteArrayInputStream(data));
			String theName = doSteam.readUTF();
			int theRecord = doSteam.readInt();
			if (theRecord < record)
				ok = true;
			doSteam.close();
	    } catch (Exception e) {
			e.printStackTrace();
			ok = false;
		}
		return ok;
}
public boolean save(String playerName, int score) {//在rs中保存本次数据
		boolean ok = false;
		ByteArrayOutputStream bo = new ByteArrayOutputStream();
		DataOutputStream doSteam = new DataOutputStream(bo);
		try {
			doSteam.writeUTF(playerName);
			doSteam.writeInt(score);
			byte data[] = bo.toByteArray();
			rs.setRecord(1, data, 0, data.length);
			doSteam.close();
			ok = true;
		} catch (Exception e) {
			ok = false;
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return ok;
	}
}