Android编程之SQLite数据库操作方法详解(2)-木庄网络博客

因为SQLite支持标准的SQL语句，因此我们可以用标准SQL语句才增删改查数据库，推荐使用占位符的sql语句，看起来更加清爽，下面是我的代码示例：

package com.hw.droid.hwcatalog;
public class DatabaseManager {
 private static DatabaseManager singleton = null;
 private SQLiteDatabase wsd = null;
 private SQLiteDatabase rsd = null;
 private DatabaseManager() {
 }
 public static DatabaseManager getInstance(Context context) {
  if (singleton == null) {
   synchronized (DatabaseManager.class) {
    if (singleton == null) {
     DatabaseHelper databaseHelper = DatabaseHelper.getInstance(context);
     singleton = new DatabaseManager();
     singleton.wsd = databaseHelper.getWritableDatabase();
     singleton.rsd = databaseHelper.getReadableDatabase();
    }
   }
  }
  return singleton;
 }
 public void initAccountTable(List<AccountData> listDatas) {
  if (listDatas == null || listDatas.size() <= 0) {
   return;
  }
  wsd.beginTransaction();
  try {
   for (AccountData data : listDatas) {
    insertAccountTable(data);
   }
   wsd.setTransactionSuccessful();
  } finally {
   wsd.endTransaction();
  }
 }
 private void insertAccountTable(AccountData accData) {
  String sql = "insert into " + AccountTable.TABLE_NAME + "(" + AccountTable.USERNAME + ", "
    + AccountTable.USERNICK + ", " + AccountTable.AVATAR_URL + ", " + AccountTable.PORTRAIT + ", "
    + AccountTable.OAUTH_TOKEN + ", " + AccountTable.OAUTH_TOKEN_SECRET + ", " + AccountTable.INFOJSON
    + " " + ")" + " values(?, ?, ?, ?, ?, ?, ?)";
  wsd.execSQL(sql,
    new Object[] { accData.getUserName(), accData.getUserNick(), accData.getUrl(), accData.getPort(),
      accData.getToken(), accData.getSecret(), accData.getJson(), accData.getThreads(), });
 }
 public List<AccountData> getAccountDatas() {
  List<AccountData> listDatas = selectAccountData();
  return listDatas;
 }
 private List<AccountData> selectAccountData() {
  List<AccountData> listAccountData = new ArrayList<AccountData>();
  String querySql = "select " + AccountTable.USERNAME + ", " + AccountTable.USERNICK + ", " + AccountTable.AVATAR_URL + ", " + AccountTable.PORTRAIT + ", " + AccountTable.OAUTH_TOKEN + ", " + AccountTable.OAUTH_TOKEN_SECRET + ", " + AccountTable.INFOJSON " " + " from " + BbsForumsTable.TABLE_NAME;
  Cursor cursor = rsd.rawQuery(querySql, null);
  if (cursor.moveToFirst()) {
   do {
    AccountData data = new AccountData();
    data.setUserName(cursor.getString(cursor.getColumnIndex(AccountTable.USERNAME)));
    data.setUserNick(cursor.getString(cursor.getColumnIndex(AccountTable.USERNICK)));
    data.setUrl(cursor.getString(cursor.getColumnIndex(AccountTable.AVATAR_URL)));
    data.setPort(cursor.getString(cursor.getColumnIndex(AccountTable.PORTRAIT)));
    data.setToken(cursor.getString(cursor.getColumnIndex(AccountTable.OAUTH_TOKEN)));
    data.setSecret(cursor.getString(cursor.getColumnIndex(AccountTable.OAUTH_TOKEN_SECRET)));
    data.setJson(cursor.getString(cursor.getColumnIndex(AccountTable.INFOJSON)));
    listAccountData.add(data);
   } while (cursor.moveToNext());
  }
  cursor.close();
  return listAccountData;
 }
 public void deleteBbsDatas() {
  String delSql = "delete from " + AccountTable.TABLE_NAME;
  wsd.execSQL(delSql);
 }
}

事物(DBTransaction)

Android中经常会用到数据库缓存，特别是wifi情况下遇到数据不一致情况需要更新缓存数据，这个时候就需要用到事物处理，保证操作的完整性和速度。Android中使用SQLite保证事务完整性示例如下：

public void initAccountTable(List<AccountData> listDatas) {
 if (listDatas == null || listDatas.size() <= 0) {
  return;
 }
 wsd.beginTransaction();
 try {
  for (AccountData data : listDatas) {
   insertAccountTable(data);
  }
  wsd.setTransactionSuccessful();
 } finally {
  wsd.endTransaction();
 }
}

通过beginTransaction()开启事务，endTransaction()结束事务，并且设置事务执行成功标识setTransactionSuccessful().

更多关于Android相关内容感兴趣的读者可查看本站专题：《Android操作SQLite数据库技巧总结》、《Android数据库操作技巧总结》、《Android编程之activity操作技巧总结》、《Android文件操作技巧汇总》、《Android开发入门与进阶教程》、《Android资源操作技巧汇总》、《Android视图View技巧总结》及《Android控件用法总结》

希望本文所述对大家Android程序设计有所帮助。

标签：SQLite

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