SQLite数据库实用的封装，sqlite数据库封装

SQLite数据库实用的封装，sqlite数据库封装

SQLite数据库简单封装:
每一张表 都会对应一个Bean 和一个Dao类
SqliteHelper 主要负责创建数据库和更新数据库 主要为其提供 创建表的sql语句 数据库名称 和数据库版本号

public class SqliteHelper extends SQLiteOpenHelper {
    private static String DB_NAME="gac.db";
    private static int VERSION = 1;
    private static final String USER_TABLE_CREATE="create table if not exists "
            +UserDao.TABLE_NAME +" ("
            +UserDao.COLUMN_ID +" INTEGER PRIMARY KEY AUTOINCREMENT, "
            +UserDao.COLUMN_NAME+" TEXT)";
    private Context context;
    private static SqliteHelper instance;
    public static SqliteHelper getInstance(Context context){
        if(instance == null){
            instance = new SqliteHelper(context.getApplicationContext());
        }
        return instance;
    }
    public SqliteHelper(Context context){
        super(context,DB_NAME,null,VERSION);
        this.context = context;
    }
    public Context getContext(){
        return context;
    }
   @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(USER_TABLE_CREATE);
    }

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

    }
    public void closeDB(){
        if(instance != null){
            try{
                SQLiteDatabase db = instance.getWritableDatabase();
                db.close();
            }catch (Exception e){
                e.printStackTrace();
            }
            instance = null;

        }
    }
}

public class UserBean {
    public String name;
   public int id;
    public UserBean(){

    }
    public UserBean(String name){
        this.name = name;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
}

4.dao类主要负责操作对应的表的增删该查 以及存储表的字段名 和表的名称 添加的数据可以利用反射进行操作

public class UserDao {
    public static String TABLE_NAME = "user";
    public static String COLUMN_ID = "id";
    public static String COLUMN_NAME = "name";
    private SqliteHelper helper = null;

    public UserDao(Context context){
        helper = new SqliteHelper(context);
    }

    //根据cursor获取userbean
    private UserBean getUserBeanByCursor(Cursor cursor){
        UserBean user = new UserBean();
        Class< ? extends UserBean> clazz = user.getClass();
        Field[] fields = clazz.getDeclaredFields();
        for(Field field :fields){
           if(field.getName().equals("id")){
                user.id = cursor.getInt(cursor.getColumnIndex("id"));
                continue;
           }
           if(field.getName().equals("name")){
                user.name = cursor.getString(cursor.getColumnIndex("name"));
                continue;
           }
        }
        return user;
    }

    //根据user获取contentvalues
    private ContentValues getContentValues(UserBean user){
        ContentValues values = new ContentValues();
        Class<? extends  UserBean> clazz = user.getClass();
        try{
            Method[] methods = clazz.getMethods();
            Object[] args = null;
            for(Method method : methods) {
                String mName = method.getName();
                if (mName.startsWith("get") && !mName.startsWith("getClass")) {
                    String filedName = mName.substring(3, mName.length()).toLowerCase();
                    Log.e("gac","fieldName:"+filedName);
                    if(filedName.equals("id")){
                        //id 让它自动增加
                        continue;
                    }
                    Object value = method.invoke(user, args);
                    if (value instanceof String) {
                        values.put(filedName, (String) value);
                    } else if (value instanceof Integer) {
                        values.put(filedName, (Integer) value);
                    }
                }
            }
        }catch (Exception e){e.printStackTrace();}
        return values;
    }

    //添加用户
    public boolean addUser(UserBean user){
        boolean flag = false;
        SQLiteDatabase database = null;
        long id = -1;
        try{
            database = helper.getWritableDatabase();
            ContentValues values = getContentValues(user);
            Class<? extends  UserBean> calzz = user.getClass();
            String tableName = TABLE_NAME;
            id = database.insert(tableName,null,values);
            flag = (id !=-1?true:false);
            if(database != null){
                database.close();
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        Log.e("gac","addUser flag:"+flag);
        return flag;
    }

    //删除用户
    public boolean delteUser(String id,String name){
        boolean flag = false;
        String wereClause = "id = ? and name = ?";

        String [] whereArgs = new String[]{id,name};
        SQLiteDatabase db = helper.getWritableDatabase();
        try{
            int res = db.delete(TABLE_NAME,wereClause,whereArgs);
            flag = (res != 0?true:false);
            if(db != null){
                db.close();
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        return flag;
    }

    //更新数据库
    public boolean updateUser(String whereClause,String[] whereArgs,UserBean user){
//        String wereClause = "id = ? and name = ?";
//        String [] whereArgs = new String[]{id,name};
        boolean flag = false;
        SQLiteDatabase db = helper.getWritableDatabase();
        try{
            ContentValues values = getContentValues(user);
            int res = db.update(TABLE_NAME,values,whereClause,whereArgs);
            flag = (res <= 0?false:true);
            db.close();
        }catch (Exception e){e.printStackTrace();}
        Log.e("gac","updateUser:"+flag);
        return flag;
    }

    //查询
    public List<UserBean>  getUserList(String sql,String[] whereArgs){
        SQLiteDatabase db = helper.getWritableDatabase();
        Cursor cursor = db.rawQuery(sql, whereArgs);
        List<UserBean> mList = null;
        if(cursor != null){
            mList = new ArrayList<>();
            while (cursor.moveToNext()){
                mList.add(getUserBeanByCursor(cursor));
            }
        }
        return mList;
    }

}

//new UserDao(this).addUser(new UserBean("gac"));
       // new UserDao(this).updateUser("id = ?",new String[]{1+""},new UserBean("gac1"));
        List<UserBean> list = new UserDao(this).getUserList("select * from " + UserDao.TABLE_NAME, null);
        for(int i =0; i < list.size(); i++){
            Log.e("gac",list.get(i).getName());
            Log.e("gac",list.get(i).getId()+"");
        }