android SQLite的简单封装

悠悠 2022-07-15 11:58 222阅读 0赞

自定义：SQLiteOpenHelper

public class SQliteDBHelper extends SQLiteOpenHelper {
        private String sql;
    
        public SQliteDBHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version,String sql) {
            //指定数据库名和版本号
            super(context, name, factory, version);
            this.sql = sql;
        }
    
        @Override
        public void onCreate(SQLiteDatabase db) {
            //db.execSQL执行创建需要的表
            db.execSQL(sql);
        }
    
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            //升级数据库
            switch (oldVersion){
                case 1:
                    //do sth
                    break;
                default:
                    break;
            }
        }
    }

封装方法：

public class NewsDBApi {
        private SQliteDBHelper dbHelper;
        private Context context;
        private static final String DB_NAME = "Data5.db"; //数据库名称
        private static final int version = 1; //数据库版本
        private String sql;//创建数据表的SQL语句
        private SQLiteDatabase database;
        private ArrayList<Data_Map> list = new ArrayList<Data_Map>();
    
        public NewsDBApi(Context context){
                this.context = context;
            sql = "create table t_news(" +
                    " _id integer primary key autoincrement," +
                    "mTitle,mFrom,mTime1,mImage1,mUrl1)";
        }
    
        public void createTB(){
              dbHelper = new SQliteDBHelper(context,DB_NAME,null,version,sql);
        }
    
        public ArrayList<Data_Map> queryData(){
            database = dbHelper.getReadableDatabase();
            Cursor c = database.query("t_news",null,null,null,null,null,null);//查询并获得游标
    
            while (c.moveToNext()){
                    int id = c.getInt(c.getColumnIndex("_id"));
                    String mTitle = c.getString(c.getColumnIndex("mTitle"));
                    String mFrom = c.getString(c.getColumnIndex("mFrom"));
                    String mImage = c.getString(c.getColumnIndex("mImage"));
                    String mUrl = c.getString(c.getColumnIndex("mUrl"));
                    long mTime = c.getLong(c.getColumnIndex("mTime"));
                    System.out.println(id+":"+mTime+":"+mTitle);
                    list.add(new Data_Map(mTitle,mTime,mFrom,mImage,mUrl));
                }
    
            c.close();
            return  list;
        }
    
        public void insertData(long mTime,String... strings){
            database = dbHelper.getWritableDatabase();
            //实例化一个ContentValues用来装载待插入的数据cv.put("username","Jack Johnson");//添加用户名
            ContentValues cv = new ContentValues();
            cv.put("mTitle",strings[0]);
            cv.put("mFrom",strings[1]);
            cv.put("mImage",strings[2]);
            cv.put("mUrl",strings[3]);
            cv.put("mTime",mTime);
            database.insert("t_news",null,cv);//执行插入操作
        }
    
        private void deleteData(long mTime){
            database = dbHelper.getWritableDatabase();
            String sql = "delete from t_user where mTime <= "+mTime;//删除操作的SQL语句
            database.execSQL(sql);//执行删除操作
        }
    
    }