Android DbHelper创建

此文章作为自己的一个记录，方便自己以后复习

public class DbHelper extends SQLiteOpenHelper {
    private SQLiteDatabase db = null;
    private Cursor cursor = null;
    private String TAG = "DBTest";
    private boolean isInit;
    private String createString;

    public DbHelper(Context context, String dbName, SQLiteDatabase.CursorFactory factory,
                    int version) {
        super(context, dbName, factory, version);
    }

    // 建表
    @Override
    public void onCreate(SQLiteDatabase db) {
        this.db = db;
        db.execSQL(createString);
    }

    public void inItDb(String createString) {
        if (isInit)
            return;
        this.createString = createString;
        this.isInit = true;
    }

    // 增
    public void insert(ContentValues values, String tableName) {
        SQLiteDatabase db = getWritableDatabase();
        System.out.println("values" + values.get("id") + values.get("name")
                + values.get("age"));
        db.insert(tableName, null, values);
        Log.i(TAG, "增加一行");
        db.close();
    }

    // 删除某一行
    public void delete(String id, String tableName) {
        // if (db == null) {
        SQLiteDatabase db = getWritableDatabase();
        // }
        db.delete(tableName, "id=?", new String[]{String.valueOf(id)});
        Log.i(TAG, "删除一行");
    }

    // 更新某一行
    public void update(ContentValues values, String string, String tableName) {
        SQLiteDatabase db = getWritableDatabase();
        db.update(tableName, values, "id=?", new String[]{string});
        db.close();
        Log.i(TAG, "更新一行");
    }

    // 按id查询
    public Cursor query(String string, String tableName) {
        SQLiteDatabase db = getWritableDatabase();
        System.out.println("id---->" + string);
        cursor = db.query(tableName, null, "id=?", new String[]{string},
                null, null, null);
        Log.i(TAG, "按id查询一行");
        return cursor;
    }

    public Cursor query(String tableName) {
        SQLiteDatabase db = getWritableDatabase();
        cursor = db.query(tableName, null, null, null, "id", null, "id");
        Log.i(TAG, "查询所有");

        return cursor;
    }

    public boolean deleteDatabase(Context context, String DBName) {
        return context.deleteDatabase(DBName);
    }

    // 按sql语句操作数据库
    public void handleBySql(String TabName) {
        String sqsl = "update sqlite_sequence set seq=0 where name='" + TabName + "'";
        SQLiteDatabase db = getWritableDatabase();
        db.execSQL(sqsl);
        Log.i(TAG, "执行sql语句");


    }

    /**
     * 判断某张表是否存在
     *
     * @return
     */
    public boolean tabbleIsExist(String tableName) {
        boolean result = false;
        if (tableName == null) {
            return false;
        }
        SQLiteDatabase db = null;
        Cursor cursor = null;
        try {
            db = this.getReadableDatabase();
            String sql = "select count(*) as c 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
        }
        return result;
    }

    // 关闭数据库
    public void close() {
        if (db != null) {
            db.close();
            db = null;
        }
        if (cursor != null) {
            cursor.close();
            cursor = null;
        }

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    //清空搜索记录
    public void deleteAllRecords() {
        db = this.getWritableDatabase();
        db.execSQL("delete from TabOther");
        db.close();
    }

    /**
     * 创建表
     *
     * @return
     */
    public static String getOther(String tablename) {
        return "Create Table " + tablename + "( id text not null, name text )";
    }
//在Activity中使用
//初始化
 dbHelper = new DbHelper(this, DB, null, 1);
        dbHelper.inItDb(dbHelper.getOther(TabOther));
//添加数据
  ContentValues values = new ContentValues();
        values.put("id", num + "");
        values.put("name", name + "");
        dbHelper.insert(values, TabOther);
//查询数据
  /**
     * 查询数据库
     *
     * @return
     */
    public List<CoordinateAlterSample> queryAll() {
        List<CoordinateAlterSample> rst = new ArrayList<CoordinateAlterSample>();
        // 解析游标
        Cursor cursor = dbHelper.query(TabOther);
        CoordinateAlterSample persion = null;
        if (cursor.moveToFirst()) {
            while (!cursor.isAfterLast()) {
                persion = new CoordinateAlterSample();
                persion.id = cursor.getString(cursor.getColumnIndex("id"));
                persion.name = cursor.getString(cursor.getColumnIndex("name"));
                rst.add(persion);
                cursor.moveToNext();
            }
        }
        return rst;
    }
//修改