6 - android - 一流楼主

结构

1：Android中数据库的创建2：ListView的优化3:数据库的分页查询以及ListView分页展示

1：Android中数据库的创建

1:写类继承SQLiteOpenHelper    public class BlackNamedb extends SQLiteOpenHelper{    public BlackNamedb(Context context) {        super(context, "blackname.db", null, 1);    }    @Override    public void onCreate(SQLiteDatabase sqLiteDatabase) {        //执行SQL语句        sqLiteDatabase.execSQL("create table blackname" +                "(_id integer primary key autoincrement,phone varchar(20),mode integer);");    }    @Override    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i2) {    }}2：重新写类私有化构造方法3：申明一个静态的当前类对象3：提供一个静态方法如果当前类的对象为空则要创建一个新的对象    public class BlacknameJDBC {    private final BlackNamedb blackNamedb;    //1:私有化构造方法    private BlacknameJDBC(Context context) {        blackNamedb = new BlackNamedb(context);    }    //2:申明当前类的对象。必须是静态的    private static BlacknameJDBC blacknameJDBC = null;    //3:提供一个静态方法如果当前类的对象为空则要创建一个新的对象    public static BlacknameJDBC getInstance(Context context){        if (blacknameJDBC==null){            blacknameJDBC = new BlacknameJDBC(context);            return blacknameJDBC;        }else {            return blacknameJDBC;        }    }4：提供增删改查等操作     /**     *     * @param phone 拦截的电话     * @param mode 拦截的类型 1是短信  2是电话  3是所有     */    public void insert(String phone , String mode){        //开启数据库做写入操作        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        //准备ContentValues 封装        ContentValues values = new ContentValues();        values.put("phone",phone);        values.put("mode",mode);        //进行写入操作 方法接收参数（表的名称，没有给值时，将null插入数据库，内容 ContentValues 用这个封装）；        writableDatabase.insert("blackname",null,values);        blackNamedb.close();    }    /**     *     * @param phone  想要删除的电话号码     */    public void delect(String phone){        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        //进行删除操作（表的名称，要删除的字段名称，要删除的字段值,要使用String类型的数组）        writableDatabase.delete("blackname","phone=?",new String[]{phone});        writableDatabase.close();    }    /**     *  根据电话号码去更新拦截模式     * @param phone 要更新的电话     * @param mode 要更新为的模式(1:短信 2:电话    3:拦截所有(短信+电话)     */    public void updata(String phone,String mode){        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        //准备数据        ContentValues values = new ContentValues();        values.put("mode",mode);        //  ava.lang.String table, android.content.ContentValues values, java.lang.String whereClause, java.lang.String[] whereArgs        //进行更新操作(表的名称，要更新的值，要更新的字段，依据什么字段更新)        writableDatabase.update("blackname",values,"mode=?",new String[]{phone});        writableDatabase.close();    }    /**     * 返回的就是数据库中所有的号码以及类型     */    public List FindAll(){        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        //查询(表名，查询的字段,查询的条件，查询的条件，查询的条件，查询的条件，  查询出来排序的方法 默认为正序，desc为倒叙)        //拿到游标        Cursor query = writableDatabase.query("blackname", new String[]{"phone", "mode"}, null, null, null, null, "_id desc");        //创建一个集合        List blackname = new ArrayList();        while (query.moveToNext()){            //生成一个BIN类放常用字段            Blacknamebin blacknamebin = new Blacknamebin();            blacknamebin.phone = query.getString(0);            blacknamebin.mode = query.getString(1);            System.out.println("blacknamebin.phone"+query.getString(0)+"````````````blacknamebin.mode"+query.getString(1));            blackname.add(blacknamebin);        }        query.close();        writableDatabase.close();        return blackname;    }    public List FindOther(int index){        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        Cursor query = writableDatabase.rawQuery("select phone,mode from blackname order by _id desc limit ?,10;", new String[]{index+""});        List blackname = new ArrayList();        while (query.moveToNext()){            //生成一个BIN类放常用字段            Blacknamebin blacknamebin = new Blacknamebin();            blacknamebin.phone = query.getString(0);            blacknamebin.mode = query.getString(1);            System.out.println("blacknamebin.phone"+query.getString(0)+"````````````blacknamebin.mode"+query.getString(1));            blackname.add(blacknamebin);        }        query.close();        writableDatabase.close();        return blackname;    }    public int getCount(){        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        Cursor cursor = writableDatabase.rawQuery("select count(*) from blackname;", null);        int count =0 ;        if (cursor.moveToNext()){            count = cursor.getInt(0);        }        cursor.close();        writableDatabase.close();        return count;    }}

2：ListView的优化

    listView优化        1:复用convertView        2:复用ViewHolder让其减少findViewById()次数        3:static ViewHolder        4:分页算法模版代码        ViewHolder  viewHolder = null;    if(convertView == null){        viewHolder = new ViewHolder();        convertView = View.inflate();        viewHolder.text1 = convertView.findViewById(R.id.text1);        convertView.setTag(viewHolder);    }else{        viewHolder = (ViewHolder)convertView.getTag();    }    viewHolder.text1.setText("文本内容");    static class ViewHolder{        TextView text1;    }

3:数据库的分页查询以及ListView分页展示

1:数据库查询指定数据写法        public List FindOther(int index){        SQLiteDatabase writableDatabase = blackNamedb.getWritableDatabase();        Cursor query = writableDatabase.rawQuery("select phone,mode from blackname order by _id desc limit ?,10;", new String[]{index+""});        List blackname = new ArrayList();        while (query.moveToNext()){            //生成一个BIN类放常用字段            Blacknamebin blacknamebin = new Blacknamebin();            blacknamebin.phone = query.getString(0);            blacknamebin.mode = query.getString(1);            blackname.add(blacknamebin);        }        query.close();        writableDatabase.close();        return blackname;    }2:监听ListView的滚动事件重写里面的onScrollStateChanged方法     lv_black_name.setOnScrollListener(new AbsListView.OnScrollListener() {            @Override            public void onScrollStateChanged(AbsListView absListView, int i) {                //滚动过程中状态发生改变                //SCROLL_STATE_IDLE  空闲状态                //SCROLL_STATE_TOUCH_SCROLL 拿手触摸着滚动滚动状态                // SCROLL_STATE_FLING 飞速滚动              条件：                //1：LV不能滚动                //2：最后一个条目可见（最后一个条目的索引值大于数据适配器中条目值-1）                //3:mIsload 这个是为了不重复加载                if (blacknamebins != null) {                    if (i == AbsListView.OnScrollListener.SCROLL_STATE_IDLE &&                            lv_black_name.getLastVisiblePosition() >= blacknamebins.size() - 1 &&                            !mIsload)                    {                        //mCount返回的是数据库中总条目的个数                        if (mCount>blacknamebins.size()){                            //开启线程加载数据                            new Thread(){                                @Override                                public void run() {                                    //获取数据库查询对象                                    blacknameSelect = BlacknameJDBC.getInstance(Blackname_Activity.this);                                    List moreData = blacknameSelect.FindOther(blacknamebins.size());                                    blacknamebins.addAll(moreData);                                    mHandler.sendEmptyMessage(0);                                    super.run();                                }                            }.start();                        }                    }                }            }            @Override            public void onScroll(AbsListView absListView, int i, int i2, int i3) {                //滚动过程中调用的方法            }        });3:通知数据适配器实时刷新调用API                    if (mAdapter!=null){                        mAdapter.notifyDataSetChanged();                    }

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