recorddb.java

J2me实现的MSN Messeger客户端程序。聊天、添加好友、删除好友、阻止好友

package vitular.ui;

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

/**
 * 记录数据库类
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: </p>
 * @author not attributable
 * @version 1.0
 */
public class RecordDB {

  private RecordStore myRecordStore;
  private RecordEnumeration myEnumeration;
  private String storeName;

  public RecordDB() {
  }

  /**
   * 删除一个库，它是一个static方法，可以在RecordDB没有open的情况下执行。
   */
  public static void deleteStore(String StoreName) {
    try {
      RecordStore.deleteRecordStore(StoreName);
    }
    catch (Exception e) {
      System.out.println(StoreName + " - " + e.getMessage());
    }
  }

  /**
   * 创建(打开)数据库，它和RecordStore的openRecordStore方法功能相同。
   */
  public void open(String StoreName) {
    storeName = StoreName;
    try {
      myRecordStore = RecordStore.openRecordStore(storeName, true);
    }
    catch (RecordStoreException rse) {
      System.out.println("open " + storeName + " error:" + rse.getMessage());
    }
  }

  /**
   * 关闭已打开的数据库
   */
  public void close() {
    try {
      myRecordStore.closeRecordStore();
    }
    catch (RecordStoreNotOpenException rsnoe) {
    }
    catch (RecordStoreException rse) {
      System.out.println("close " + storeName + " error:" + rse.getMessage());
    }
  }

  /**
   * 求得数据库的记录数
   */
  public int getNumRecords() {
    int j = 0;
    try {
      j = myRecordStore.getNumRecords();
    }
    catch (RecordStoreNotOpenException rsnoe) {
      System.out.println("getNumRecord error:" + rsnoe.getMessage());
    }
    return j;
  }

  /**
   *增加记录，返回新增加记录的记录序号<br>
   *Record为要增加记录的内容，方法内部已经将Record字符串转换为了UTF编码。
   */
  public int addRecord(String Record) {
    int curRecord = 0;
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    DataOutputStream outputStream = new DataOutputStream(baos);
    try {
      outputStream.writeUTF(Record);
      byte[] b = baos.toByteArray();
      curRecord = myRecordStore.addRecord(b, 0, b.length);
    }
    catch (Exception e) {
      System.out.println("Engine Error:addRecord");
    }
    return curRecord;
  }

  /**
   *增加记录
   */
  public int addRecord(byte[] b) {
    int curRecord = -1;
    try {
      curRecord = myRecordStore.addRecord(b, 0, b.length);
    }
    catch (Exception e) {
      System.out.println("Engine Error:addRecord");
    }

    return curRecord;
  }

  /**
   *得到一条记录的内容<br>
   *RecordNum为要取的记录号，RecordDB的起始号从1开始，返回的字符串已转换为UTF编码。
   */
  public String getRecord(int RecordNum) {
    String record_str = null;
    try {
      byte[] b = myRecordStore.getRecord(RecordNum);
      ByteArrayInputStream bais = new ByteArrayInputStream(b);
      DataInputStream inputStream = new DataInputStream(bais);
      record_str = inputStream.readUTF();
    }
    catch (Exception e) {
      System.out.println("Engine Error:getRecord");
    }
    return record_str;
  }

  /**
   *得到记录
   * *RecordNum为要取的记录号，RecordDB的起始号从1开始
   */
  public byte[] getBytesRecord(int recordNum) {
    try {
      byte[] b = myRecordStore.getRecord(recordNum);
      return b;
    }
    catch (Exception e) {
      System.out.println("Engine Error:getRecord byte");
      return null;
    }
  }

  /**
   *修改一条记录，方法内部已经将Record字符串转换为了UTF编码。
   */
  public void setRecord(int RecordId, String Record) {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    DataOutputStream outputStream = new DataOutputStream(baos);
    try {
      outputStream.writeUTF(Record);
      byte[] b = baos.toByteArray();
      myRecordStore.setRecord(RecordId, b, 0, b.length);
    }
    catch (Exception e) {
    }
  }

  /**
   *删除一条记录，RecordDB的起始号从1开始
   */
  public void deleteRecord(int RecordId) {
    try {
      myRecordStore.deleteRecord(RecordId);
    }
    catch (Exception e) {
    }
  }

  /**
   * 取出Str字符串的某个字段值，FieldNo为字段号(起始位置为1)，SeparatorChar为字段分隔符
   * 见mmae.util.Tool.getField
   */
  public String getField(String Str, int FieldNo, String SeparatorChar) {
    return Util.getField(Str, FieldNo, SeparatorChar);
  }

}