经常用得到的安卓数据库基类

//创建数据库  
public class DBCreate {  
    public static void CreateDatabase(SQLiteDatabase db) {  
        db.beginTransaction();  
        try {  
            create_NetTaskBuffer(db);  
  
            insert_SQL(db);  
  
            db.setTransactionSuccessful();  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            db.endTransaction();  
        }  
    }  
  
    // 缓存  
    private static void create_NetTaskBuffer(SQLiteDatabase db) {  
        db.execSQL("DROP TABLE IF EXISTS NetTaskBuffer");  
        StringBuilder sql = new StringBuilder();  
        sql.append("CREATE TABLE IF NOT EXISTS NetTaskBuffer (");  
        sql.append(" id INTEGER PRIMARY KEY AUTOINCREMENT,"); // 这一列不能修改  
        sql.append(" label TEXT COLLATE NOCASE,"); //  
        sql.append(" param TEXT COLLATE NOCASE,"); //  
        sql.append(" result TEXT COLLATE NOCASE,"); //  
        sql.append(" remark TEXT COLLATE NOCASE,");  
        sql.append(" time LONG)"); //  
        db.execSQL(sql.toString());  
    }  
  
    // 插入语句,初始化数据库使用  
    private static void insert_SQL(SQLiteDatabase db) {  
          
    }  
}  
  
  
  
//----------------------数据库操作基类--------------------------------------//  
  
  
/** 
 * 数据库基本操作类,数据库的创建,更新的操作都在这里进行 
 *  
 * @author yizhe 
 * @date 2014-9-11 
 */  
public abstract class DBHelper extends SQLiteOpenHelper {  
  
    static String name = "hk.db"; // 数据库名称  
    static CursorFactory cursorFactory = null;  
    static int version = 1000;// 初始版本:1000  
    Context context;  
  
    protected ContentValues contentValues; // cursor对象转行中介,给子类使用  
  
    protected String tableName;  
  
    protected DBHelper(Context context, String tableName) {  
        super(context, name, cursorFactory, version);  
        this.context = context;  
        this.tableName = tableName;  
    }  
  
    /** 
     * 软件第一次安装的时候会调用,覆盖安装不会调用 
     */  
    public void onCreate(SQLiteDatabase db) {  
        // 所有表的创建过程都在这里进行  
        DBCreate.createDatabase(db);  
    }  
  
    /** 
     * 覆盖安装,当版本号version发生变化的时候,这个方法才会被调用,而且只执行一次 
     */  
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {  
        onCreate(db);  
        // if (oldVersion < 109) {  
        // onCreate(db);  
        // } else {  
        // }  
    }  
  
    /** 
     * 每次成功打开数据库后首先被执行 
     */  
    public void onOpen(SQLiteDatabase db) {  
        super.onOpen(db); // 每次成功打开数据库后首先被执行  
    }  
  
    public void finalize() {  
        close();  
    }  
  
    // --------------------------sql方法---------------------------------//  
    /** 
     * 执行sql,没有返回 
     */  
    public void execSQL(String sql) {  
        System.out.println("==execSQL==" + sql);  
        SQLiteDatabase db = getWritableDatabase();  
        db.execSQL(sql);  
        db.close();  
    }  
  
    /** 
     * 批量执行sql,内部启用事务 
     *  
     * @param list 
     *            sql列表 
     * @return 是否执行成功 
     */  
    public boolean execSQLBatch(ArrayList<String> list) {  
        SQLiteDatabase db = getWritableDatabase();  
        db.beginTransaction();  
        try {  
            for (String sql : list) {  
                db.execSQL(sql);  
            }  
            db.setTransactionSuccessful();  
        } catch (Exception e) {  
            e.printStackTrace();  
            return false;  
        } finally {  
            db.endTransaction();  
            db.close();  
        }  
        return true;  
    }  
  
    /** 
     * 根据id删除记录 
     *  
     * @param id 
     *            表中必须有"id"字段 
     * @return the number of rows affected if a whereClause is passed in, 0 
     *         otherwise. To remove all rows and get a count pass "1" as the 
     *         whereClause. 
     */  
    public int delete(int id) {  
        SQLiteDatabase db = getWritableDatabase();  
        int result = db.delete(tableName, "id=?", new String[] { id + "" });  
        db.close();  
        return result;  
    }  
  
    /** 
     * 删除: 只需要写where 条件(不带where) 和 参数 
     *  
     * @param whereStr 
     *            例如: "id=?" 
     * @param arr 
     *            例如: new String[] { "123" } 
     * @return 受影响的行 
     */  
    public int delete(String whereStr, String[] arr) {  
        SQLiteDatabase db = getWritableDatabase();  
        int result = db.delete(tableName, whereStr, arr);  
        db.close();  
        return result;  
    }  
  
    /** 
     * 清空表 
     */  
    public void clearTable() {  
        SQLiteDatabase db = getWritableDatabase();  
        db.execSQL("delete from " + tableName);  
        db.close();  
    }  
  
    /** 
     * 通用查询,多用于事务中 
     */  
    public static Cursor Query(SQLiteDatabase db, String sql) {  
        System.out.println("==Query==" + sql);  
        return db.rawQuery(sql, new String[] {});  
    }  
  
    /** 
     * 通用执行sql,,多用于事务中 
     *  
     */  
    public static void execSQL(SQLiteDatabase db, String sql) {  
        System.out.println("==execSQL==" + sql);  
        db.execSQL(sql);  
    }  
  
}  
  
//-------------------------下面是一个具体实现的DEMO-------------------------------//  
/** 
 * dao类,实现基本的数据库操作<br/> 
 * 需要保存到数据库中的对象的属性不能使用基本类型,建议只使用Integer 和 String<br/> 
 * 做为通用对象,从demo创建只要修改tableName即可 
 *  
 * @author yizhe 
 * @date 2012-5-18 
 */  
public class NetTaskBufferDao extends DBHelper {  
    int expiryDays = 10; // 数据缓存有效期  
  
    public NetTaskBufferDao(Context context) {  
        super(context, "NetTaskBuffer");  
    }  
  
    // pojo的整数都需要使用Long类型 或者Integer类型 建议使用Long  
    public void iniContentValues(NetTaskBuffer pojo) {  
        contentValues = new ContentValues();  
        contentValues.put("id", pojo.id);  
        contentValues.put("label", pojo.label);  
        contentValues.put("param", pojo.param);  
        contentValues.put("result", pojo.result);  
        contentValues.put("remark", pojo.remark);  
        contentValues.put("time", pojo.time);  
    }  
  
    public NetTaskBuffer setBaseItem(Cursor cursor) {  
        NetTaskBuffer pojo = new NetTaskBuffer();  
        pojo.id = cursor.getInt(cursor.getColumnIndex("id"));  
        pojo.label = cursor.getString(cursor.getColumnIndex("label"));  
        pojo.param = cursor.getString(cursor.getColumnIndex("param"));  
        pojo.result = cursor.getString(cursor.getColumnIndex("result"));  
        pojo.remark = cursor.getString(cursor.getColumnIndex("remark"));  
        pojo.time = cursor.getLong(cursor.getColumnIndex("time"));  
        return pojo;  
    }  
  
    // --------------------自定义方法--------------------------------//  
    public String getBuffer(String label, String param) {  
        String sql = "select * from " + tableName  
                + " where label=? and param=? ";  
        NetTaskBuffer obj = getOneAsSQL(sql, new String[] { label, param });  
        if (null == obj) {  
            return null;  
        }  
        Date time = new Date(obj.time);  
        Calendar c = Calendar.getInstance();  
  
        c.add(Calendar.DAY_OF_MONTH, -expiryDays);  
        if (time.compareTo(c.getTime()) < 0) {  
            delete(obj.id);  
            return null;  
        }  
        return obj.result;  
    }  
  
    public String getBuffer(String label, String param, String remark) {  
        String sql = "select * from " + tableName  
                + " where label=? and param=? and remark=?";  
        NetTaskBuffer obj = getOneAsSQL(sql, new String[] { label, param,  
                remark });  
        if (null == obj) {  
            return null;  
        }  
        Date time = new Date(obj.time);  
        Calendar c = Calendar.getInstance();  
  
        c.add(Calendar.DAY_OF_MONTH, -expiryDays);  
        if (time.compareTo(c.getTime()) < 0) {  
            delete(obj.id);  
            return null;  
        }  
        return obj.result;  
    }  
  
    public void deleteBuffer(String label) {  
        String whereSql = " label=?";  
        delete(whereSql, new String[] { label });  
    }  
  
    public void deleteBuffer(String label, String param) {  
        String whereSql = " label=? and param=?";  
        delete(whereSql, new String[] { label, param });  
    }  
  
    public void deleteBuffer(String label, String param, String remark) {  
        String whereSql = " label=? and param=? and remark=?";  
        delete(whereSql, new String[] { label, param, remark });  
    }  
  
    // --------------------基础方法---------------------------------//  
  
    /** 
     * 根据sql获取list 
     */  
    public ArrayList<NetTaskBuffer> getListAsSQL(String sql) {  
        SQLiteDatabase db = getReadableDatabase();  
        Cursor cursor = db.rawQuery(sql, new String[] {});  
        ArrayList<NetTaskBuffer> itemList = new ArrayList<NetTaskBuffer>();  
        for (cursor.moveToFirst(); !(cursor.isAfterLast()); cursor.moveToNext()) {  
            itemList.add(setBaseItem(cursor));  
        }  
        cursor.close();  
        db.close();  
        return itemList;  
    }  
  
    /** 
     * 根据ID获取一条记录 
     */  
    public NetTaskBuffer getById(int id) {  
        String sql = "select * from " + tableName + " where id=" + id;  
        return getOneAsSQL(sql, null);  
    }  
  
    /** 
     * 返回结果中的提一条记录 
     */  
    public NetTaskBuffer getOneAsSQL(String sql, String[] arr) {  
        SQLiteDatabase db = getReadableDatabase();  
        Cursor cursor = db.rawQuery(sql, arr);  
        try {  
            if (null != cursor && cursor.getCount() > 0) {  
                cursor.moveToFirst();  
                return setBaseItem(cursor);  
            }  
        } finally {  
            cursor.close();  
            db.close();  
        }  
        return null;  
    }  
  
    /** 
     * 保存对象到数据库,自动判断插入还是更像 
     *  
     * @return 返回更新的记录数,或者 插入数据的id,如果返回值<=0表示失败 
     */  
    public long save(NetTaskBuffer pojo) {  
        if (null == pojo.time || 0 == pojo.time) {  
            pojo.time = new Date().getTime();  
        }  
        Long idOrEffectRows = 0l;  
        if (null == pojo.id || pojo.id < 1) {  
            idOrEffectRows = insert(pojo);  
        } else {  
            idOrEffectRows = (long) update(pojo);  
        }  
        return idOrEffectRows;  
    }  
  
    /** 
     * 添加数据,自动插入id 
     *  
     * @return the row ID of the newly inserted row, or -1 if an error occurred 
     */  
    public long insert(NetTaskBuffer pojo) {  
        SQLiteDatabase db = getWritableDatabase();// 获取可写SQLiteDatabase对象  
        iniContentValues(pojo); // ContentValues类似map，存入的是键值对  
        long result = db.insert(tableName, null, contentValues);  
        if (result != -1) {  
            pojo.id = (int) result;  
        }  
        db.close();  
        return result;  
    }  
  
    /** 
     * 根据ID更新记录的，跟插入的很像 
     *  
     * @return the number of rows affected 
     *  
     */  
    public int update(NetTaskBuffer pojo) {  
        SQLiteDatabase db = getWritableDatabase();  
        iniContentValues(pojo); // 初始化键值对  
        int result = db.update(tableName, contentValues, "id=?",  
                new String[] { pojo.id + "" });  
        db.close();  
        return result;  
    }  
  
}