android数据库版本升级总结

import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

/**
 * @description：数据库帮助类
 * @author samy
 * @date 2015年6月16日 下午8:41:18
 */
public class DBHelper extends SQLiteOpenHelper {
	public static final String NAME = Constant.DATABASE_NAME; // DB name
	public static final List<DBUpdateListener> mUpdateList = new ArrayList<DBUpdateListener>();
	public DBHelper(Context context) {
		// super(context, NAME, null, Constant.DATABASE_VERSION);
		super(context, NAME, null, 133);
		// version 187:新增tips表和app_recommend表
		// version 188:新增matchsync表
		// version 189:新增widget_status表
	}
	public DBHelper(Context context, String name, CursorFactory factory, int version) {
		super(context, name, factory, version);
	}
	/**
	 * 用户第一次使用软件时调用的操作，用于获取数据库创建语句（SW）,然后创建数据库
	 */
	@Override
	public void onCreate(SQLiteDatabase db) {
		IMDebug.print("创建--会员版--数据库!!!");
		db.execSQL(BaseModelTool.getCreateTableSql(UserInfo.class));
		db.execSQL(BaseModelTool.getCreateTableSql(ShopIndustry.class)); // 行业
		/** V2.0.0版本的数据库变更,增加最后一次聊天的表 */
		db.execSQL(BaseModelTool.getCreateTableSql(GroupAssistantStatisticModel.class));
	}
	/**
	 * 数据库更新,如果数据库有更新，那么调用BaseModelTool.getAlterTableSql((Class<?> modelType, String string);方法向表中添加相应新字段
	 */
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		int tempVersion = oldVersion;
		
		addDBUpdateListener();
		for (int i = 0; i < mUpdateList.size(); i++) {
			if (mUpdateList.get(i).getmPreVersionNo() >= tempVersion) {
				mUpdateList.get(i).onUpgrade(db, tempVersion, newVersion);
				tempVersion = mUpdateList.get(i).getmCurrVersionNo();
			}
		}
		mUpdateList.clear();
	}
	private void addDBUpdateListener() {
		// v1.5.7 --> v2.0.0 个人信息里面惠信余额和银行卡数的添加
		mUpdateList.add(new DBUpdate_V131_V132());
	}
	/**
	 * @description：观察者模式 IM数据库：v1.5.7 --> v2.0.0
	 * @author samy
	 * @date 2015年6月16日 下午8:39:43
	 */
	private class DBUpdate_V131_V132 extends DBUpdateListener {
		public DBUpdate_V131_V132() {
			setmPreVersionNo(132);
			setmCurrVersionNo(133);
		}
		@Override
		public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
			String sql="";
			if (!checkColumnExist(db, "userInfo", "earnings")) {
				sql = "alter table userInfo add earnings text;";
			}
			if (!checkColumnExist(db, "userInfo", "accountbalance")) {
				sql = "alter table userInfo add accountbalance text;";
			}
			if (!checkColumnExist(db, "userInfo", "bankcardnum")) {
				sql = "alter table userInfo add bankcardnum text;";
			}
			db.execSQL(sql);
			
			db.execSQL(BaseModelTool.getDropTableSql(IMGroupRelation.class));
		}
	}
	/**
	 * @description：判断字段是否在这个表中存在，对字段进行处理时要记得先判断
	 * @author samy
	 * @date 2015年6月16日 下午8:36:39
	 */
	private boolean checkColumnExist(SQLiteDatabase db, String tableName, String columnName) {
		boolean result = false;
		Cursor cursor = null;
		try {
			cursor = db.rawQuery("SELECT * FROM " + tableName + " LIMIT 0", null);// 查询一行
			result = cursor != null && cursor.getColumnIndex(columnName) != -1;
		}
		catch (Exception e) {
			Log.e("SQL", "checkColumnExists..." + e.getMessage());
		}
		finally {
			if (null != cursor && !cursor.isClosed()) {
				cursor.close();
			}
		}
		return result;
	}
	/**
	 * @description：判断表是否存在
	 * @author samy
	 * @date 2015年6月16日 下午8:36:19
	 */
	public boolean tabbleIsExist(SQLiteDatabase db, String tableName) {
		boolean result = false;
		if (tableName == null) { return false; }
		Cursor cursor = null;
		try {
			db = this.getReadableDatabase();
			String sql = "select count(*) from sqlite_master where type =‘table‘ and name =‘" + tableName.trim() + "‘ ";
			cursor = db.rawQuery(sql, null);
			if (cursor.moveToNext()) {
				int count = cursor.getInt(0);
				if (count > 0) {
					result = true;
				}
			}
		}
		catch (Exception e) {
			// TODO: handle exception
		}
		finally {
			if (null != cursor && !cursor.isClosed()) {
				cursor.close();
			}
		}
		return result;
	}
	private abstract class DBUpdateListener {
		private int mPreVersionNo;
		private int mCurrVersionNo;
		public abstract void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion);
		@SuppressWarnings("unused")
		public int getmCurrVersionNo() {
			return mCurrVersionNo;
		}
		protected void setmCurrVersionNo(int mCurrVersionNo) {
			this.mCurrVersionNo = mCurrVersionNo;
		}
		@SuppressWarnings("unused")
		public int getmPreVersionNo() {
			return mPreVersionNo;
		}
		protected void setmPreVersionNo(int mPreVersionNo) {
			this.mPreVersionNo = mPreVersionNo;
		}
	}
}