J2ME 实现永久存储

J2ME实现永久存储本来是RMS的事，可是我却在关掉程序后没有解决掉这个事情。索性就自己模拟RMS的原理来写了一个数据库进行永久性的存储！

     一 ：实现的原理

　　　　主要是利用了FileConnection这个接口与外界通信！ 存储的数据结构是使用" | " 来分隔每一个存储的元素。

               默认的存储位置是　 ：** /WTK22/appdb/DefaultColorPhone/filesystem/root1这是在模拟器上的这是位置！

               程序中的虚拟位置是 ："file:///root1/mydb.txt" ;

　　　　　如果在真机上的话： "file:///e:/1.txt"　表示的是ＳＤ卡里面

 

　　二：代码部分

　　　　　　　/*主要作用是进行读取和写入数据*/public class RMS {private FileConnection fc ;private InputStream input;private OutputStream output;public String strData;public byte byteData[];private static final String path = "file:///root1/mydb.txt" ;/*byte 与 String之间的相互转化*/public String byteToString(byte[]byteData) {return strData = new String(byteData);}public byte[]stringToByte(String strData){return strData.getBytes();}/*写入*/public void write(String data){try {fc = (FileConnection) Connector.open(path); if (!fc.exists()) { fc.create();} else {fc.truncate(0);} output = fc.openOutputStream(); output.write(stringToByte(data)); } catch (IOException e) {e.printStackTrace();} finally { if (output != null) { try { output.close(); } catch (IOException e) { e.printStackTrace(); } output = null; } if (fc != null) { try { fc.close(); } catch (IOException e) { e.printStackTrace(); } fc = null; } } }/*读取*/public String read(){try {fc = (FileConnection) Connector.open(path);if (!fc.exists()) { return "";}input = fc.openInputStream();byteData = new byte[(int) fc.fileSize()]; input.read(byteData);} catch (IOException e) {e.printStackTrace();} finally { if (input != null) { try { input.close(); } catch (IOException e) { e.printStackTrace(); } input = null; } if (fc != null) { try { fc.close(); } catch (IOException e) { e.printStackTrace(); } fc = null; } } return byteToString(byteData);}} 

 

 

　　　　　　　/*主要作用是进行显示结果*/public class RmsCanvas extends Canvas {private String[]allData ; public String[] getAllData() {return allData;}public void setAllData(String[] allData) {this.allData = allData;}public void paint(Graphics g) { drawBg(g); drawScore(g);}public void drawScore(Graphics g){ if (allData==null) return ;for (int i = 0; i < allData.length; i++) { if (i < 3) { g.drawString(allData[i],10+i*70, 43, 0);} if (i>=3&&i<6) { g.drawString(allData[i],10+(i-3)*70, 73, 0);} if (i>=6&&i<9) { g.drawString(allData[i],10+(i-6)*70, 103, 0);}}}// draw bgpublic void drawBg(Graphics g){g.setGrayScale(180);g.fillRect(0, 0, getWidth(), getHeight());g.setColor(0xff0000);g.drawString("name", 7, 10, 0);g.drawString("time", 70, 10, 0);g.drawString("score", 140, 10, 0);g.drawString("rank", 210, 10, 0);g.setColor(0xffff00); g.drawRect(3, 3, getWidth()-7, getHeight()-7);g.drawLine(3, 33, getWidth()-5,33);g.drawLine(3, 63, getWidth()-5,63);g.drawLine(3, 93, getWidth()-5,93);g.drawLine(3, 123, getWidth()-5,123);g.drawString("第一名", 200, 43, 0);g.drawString("第二名", 200, 73, 0);g.drawString("第三名", 200, 103, 0);g.setColor(0xffff00);g.fillRect(3, 240, 50, 20);g.fillRect(195, 240, 50, 20);}} 

　　　　　　　/*工具类主要作用是对字符串的解析和构建*/public class StringOper { public String data[]; public String oldData[]; public String newData[]; public void initString(int dataLength) { if (dataLength ==3) { newData = new String[3]; data = new String[3]; for (int i = 0; i < newData.length; i++) { newData[i]=""; } for (int i = 0; i < data.length; i++) { data[i]=""; } } if (dataLength == 9) { oldData = new String[9]; data = new String[9]; for (int i = 0; i < oldData.length; i++) { oldData[i]=""; } for (int i = 0; i < data.length; i++) { data[i]=""; }} } //String split public String[] split(String str , int dataLength) { initString(dataLength); int index = 0; for (int i = 0; i < data.length; i++) { for (int j= index; j < str.length(); j++) { char c = str.charAt(j); index++; if (c=='|') { break; } data[i]+=String.valueOf(c); }} if (dataLength == 9) { oldData = data ; } if (dataLength == 3) { newData = data; } return data; } // new data public void newRank(int rank) { switch(rank) { case 2: for (int i = 8; i >= 3 ; i--) { oldData[i] = oldData[i-3]; } for (int i = 0; i < newData.length; i++) { oldData[i] = newData[i];} break ; case 5: for (int i = 8; i > 5 ; i--) { oldData[i] = oldData[i-3]; } for (int i = 3; i < 6; i++) { oldData[i] = newData[i-3];} break ; case 8: for (int i = 8; i > 5 ; i--) { oldData[i] = newData[i-5]; } break ; } } // newData coming type : name|time|score also Ext interface public void insert(String newData) { int score = Integer.parseInt(split(newData , 3)[2]); for (int i = 2; i <oldData.length; i+=3) { if (compare(score , Integer.parseInt(oldData[i]))) { newRank(i); break; } } } //score compare public boolean compare(int newData , int oldData) { return newData > oldData; } // Ext interface public String[] listData() { return oldData; } //get String public String getString() { String str = ""; for (int i = 0; i < oldData.length; i++) { str+=oldData[i]+"|"; } return str; } } 

 

　　　　　　　　/*测试类*/public class Main extends MIDlet {public Main() {StringOper sp = new StringOper();String str ="pdw1|100|10|pdw2|50|5|pdw3|30|3"; //从本地而来RMS rms = new RMS(); rms.write(str); sp.split(rms.read() , 9); //显示排行榜的时候调用 // sp.insert("abc|8|11"); //新加入的数据(在插入的地方调用) // rms.write(sp.getString());//插入后调用保存新的数据 RmsCanvas can = new RmsCanvas(); can.setAllData(sp.listData()); Display.getDisplay(this).setCurrent(can);}protected void destroyApp(boolean arg0) throws MIDletStateChangeException {// TODO Auto-generated method stub}protected void pauseApp() {// TODO Auto-generated method stub}protected void startApp() throws MIDletStateChangeException {// TODO Auto-generated method stub}}