recordlistener_midlet.java

本光盘是《J2ME无线移动游戏开发》一书的配套光盘

package ch12;

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

public class RecordListener_MIDlet
    extends MIDlet
    implements RecordListener {

  //声明一个Display对象
  Display display = Display.getDisplay(this);

  //声明一个随机数
  Random random = new java.util.Random();

  //声明一个记录存储
  RecordStore rs = null;

  //声明一个记录枚举集
  RecordEnumeration re = null;

  /*
   1.构造器
   */
  public RecordListener_MIDlet() {
    try {
      rs.deleteRecordStore("test");
      rs = RecordStore.openRecordStore("test", true);
      rs.addRecordListener(this);
      re = rs.enumerateRecords(null, null, true);
      while (rs.getNumRecords() <= 5) {
        int type = (random.nextInt() >>> 31) + (random.nextInt() >>> 31);
        byte[] data;
        switch (type) {
          case 0:
            data = "Here is the new record".getBytes();
            rs.addRecord(data, 0, data.length);
            break;
          case 1:
            if (re.hasNextElement()) {
              rs.deleteRecord(re.nextRecordId());
            }
            break;
          case 2:
            if (re.hasNextElement()) {
              data = "Here is the new record".getBytes();
              rs.setRecord(re.nextRecordId(), data, 0, data.length);
            }
            break;
        }
      }
    }
    catch (RecordStoreException rse) {
      System.out.println(rse.getMessage());
    }
  }

  //响应添加记录事件
  public void recordAdded(RecordStore recordStore, int recordId) {
    System.out.println("警告：记录ID号为" + recordId + "的记录被添加！");
  }

  //响应修改记录事件
  public void recordChanged(RecordStore recordStore, int recordId) {
    System.out.println("警告：记录ID号为" + recordId + "的记录被修改！");
  }

  //响应删除记录事件
  public void recordDeleted(RecordStore recordStore, int recordId) {
    System.out.println("警告：记录ID号为" + recordId + "的记录被删除！");
  }

  //启动应用程序
  public void startApp() {
  }

  //挂起应用程序
  public void pauseApp() {
  }

  //撤销应用程序
  public void destroyApp(boolean unconditional) {
    try {
      if (rs != null) {
        rs.closeRecordStore();
      }
    }
    catch (RecordStoreException rse) {
      System.out.println(rse.getMessage());
    }

  }
}