Android实现省市区三级联动的效果

/**     * 将assets下的资源复制到应用程序的databases目录下     * @param context 上下文     * @param fileName assets下的资源的文件名     */    public static void copyAssetsToDB(Context context, String fileName) throws IOException {        //数据库的存储路径,该路径在：data/data/包名/databases目录下，        String destPath = context.getDatabasePath("").getPath();        Log.i("tag","path---->"+destPath);        File file = new File(destPath);        if (!file.exists()) {            file.mkdirs();  //创建目录        }else {            return;        }
        //打开assest文件，获得输入流        InputStream is = context.getAssets().open(fileName);        BufferedInputStream bis = new BufferedInputStream(is);
        //获得写入文件的输出流        FileOutputStream fos = new FileOutputStream(destPath +File.separator + fileName);        BufferedOutputStream bos = new BufferedOutputStream(fos);
        byte[] data = new byte[2 * 1024];        int len;        while ((len = bis.read(data)) != -1){            bos.write(data, 0, len);        }
        bos.flush();        bis.close();        bos.close();    }

//打开数据库文件的完整路径，来获得sqlite数据库对象SQLiteDatabase database = SQLiteDatabase.openOrCreateDatabase(dbPath, null);//数据库查询操作Cursor cursor = database.rawQuery(sql, null);        if (cursor != null) {            while (cursor.moveToNext()) {               //......查询结果的操作            }            cursor.close();        }

    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_main"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.zx.copydatabase.MainActivity"    android:orientation="horizontal"    android:gravity="center"    android:padding="10dp">
                android:id="@+id/province_picker"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="1"        android:focusable="true"        android:focusableInTouchMode="true"/>
            android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="省"        android:textColor="#000"        android:layout_marginLeft="10dp"        android:layout_marginRight="10dp"/>
                android:id="@+id/city_picker"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="1"        android:focusable="true"        android:focusableInTouchMode="true"/>
            android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="市"        android:textColor="#000"        android:layout_marginLeft="10dp"        android:layout_marginRight="10dp"/>
                android:id="@+id/area_picker"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="1"        android:focusable="true"        android:focusableInTouchMode="true"/>
            android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="区"        android:textColor="#000"        android:layout_marginLeft="10dp"        android:layout_marginRight="10dp"/>

public class MainActivity extends AppCompatActivity {
    private static final String DB_NAME = "mydb.db"; //数据库名称
    private NumberPicker provincePicker, cityPicker, areaPicker; //省市区选择器    private AddressManager manager; //自定义的地址管理器
    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);

        //拷贝assets下的文件"mydb.db"到 应用的databases目录下        try {            MyUtils.copyAssetsToDB(this, DB_NAME);        } catch (IOException e) {            e.printStackTrace();        }
        //初始化“地址管理器”对象        manager = new AddressManager(getDatabasePath(DB_NAME).getPath());
        initView();        initProvince();    }
    //初始化View    private void initView() {        provincePicker = (NumberPicker) findViewById(R.id.province_picker);        cityPicker = (NumberPicker) findViewById(R.id.city_picker);        areaPicker = (NumberPicker) findViewById(R.id.area_picker);    }
    //设置“省份”选择器的数据    private void initProvince() {        List provinceList = manager.getProvinces(); //获取所有的省份        //设置省份的值        final String[] provinces = provinceList.toArray(new String[provinceList.size()]);        provincePicker.setDisplayedValues(provinces);        provincePicker.setMinValue(0); //设置第一个值        provincePicker.setMaxValue(provinces.length - 1); //设置最后一个值        //默认的省份的位置        int defaultProvince = provinces.length / 2 == 0 ? provinces.length / 2 : provinces.length / 2 + 1;        provincePicker.setValue(defaultProvince); //设置当前值
        //根据当前默认的省份来设置对应的市        showCityByProvince(provinces[provincePicker.getValue()]);
        //省份的选择事件        provincePicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {            @Override            public void onValueChange(NumberPicker picker, int oldVal, int newVal) {                Log.i("tag", "newVal--->" + newVal);                showCityByProvince(provinces[newVal]);            }        });    }
    //根据选择的省份名来显示城市名    private void showCityByProvince(String province) {        List cityList = manager.getCities(province);        //设置城市的值        final String[] cities = cityList.toArray(new String[cityList.size()]);        cityPicker.setDisplayedValues(null); //清空之前的选择的数据        cityPicker.setMinValue(0); //设置第一个值        cityPicker.setMaxValue(cities.length - 1); //设置最后一个值        cityPicker.setDisplayedValues(cities);
        //根据当前默认的城市来设置对应的区        showAreaByCity(cities[cityPicker.getValue()]);
        //城市的选择事件        cityPicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {            @Override            public void onValueChange(NumberPicker picker, int oldVal, int newVal) {                showAreaByCity(cities[newVal]);            }        });    }
    //根据选择的城市名来显示区名    private void showAreaByCity(String city) {        List areaList = manager.getAreas(city);        //设置区的值        String[] areas = areaList.toArray(new String[areaList.size()]);        areaPicker.setDisplayedValues(null);        areaPicker.setMinValue(0); //设置第一个值        areaPicker.setMaxValue(areas.length - 1); //设置最后一个值        areaPicker.setDisplayedValues(areas);    }}

/** * "省市区"数据库操作类 */
public class AddressManager {
    //ssq表的字段的名字    private static final String TABLE_NAME = "ssq"; //表名    private static final String PROVINCE = "province"; //省份名称    private static final String CITY = "city"; //市的名称    private static final String AREA = "area"; //区的名称
    private SQLiteDatabase database; //sqlite数据库对象
    /**     * @param dbPath 数据库中“省市区”表的路径     */    public AddressManager(String dbPath) {        database = SQLiteDatabase.openOrCreateDatabase(dbPath, null);    }
    /**     * 查询所有省份     *     * @return 所有的省份名称     */    public List getProvinces() {
        String sql = "select distinct " + PROVINCE + " from " + TABLE_NAME;        Cursor cursor = database.rawQuery(sql, null);        List provinceList = new ArrayList<>();        if (cursor != null) {            while (cursor.moveToNext()) {                String province = cursor.getString(cursor.getColumnIndex("province"));                Log.i("tag", "province----->" + province);                provinceList.add(province);            }            cursor.close();        }        return provinceList;    }
    /**     * 查询指定省份或直辖市的所有市的集合     *     * @param province 省份名称     * @return 查询到的所有城市     */    public List getCities(String province) {        String sql = "select distinct " + CITY + " from " + TABLE_NAME + " where " + PROVINCE + " = ?";        Cursor cursor = database.rawQuery(sql, new String[]{province});        List addressList = new ArrayList<>();        while (cursor.moveToNext()) {            String city = cursor.getString(cursor.getColumnIndex(CITY));            Log.i("tag", "city----->" + city);            addressList.add(city);        }        //关闭游标        cursor.close();        return addressList;    }

    /**     * 查询指定市的所有区的列表的List集合     *     * @param city 市的名称     * @return 查询到的所有区     */    public List getAreas(String city) {        //获取指定市的所有区的列表的sql语句        String sql = "select distinct " + AREA + " from " + TABLE_NAME + " where " + CITY + " = ?";        Cursor cursor = database.rawQuery(sql, new String[]{city});        List addressList = new ArrayList<>();        while (cursor.moveToNext()) {            //获取区的名称            String area = cursor.getString(cursor.getColumnIndex(AREA));            Log.i("tag", "area----->" + area);            //把所有的区添加到List集合            addressList.add(area);        }        //关闭游标        cursor.close();        return addressList;    }}

np = (NumberPicker) findViewById(R.id.numberPicker1);  String[] city = {"北京","上海","广州","深圳","成都","天津"};  np.setDisplayedValues(city);  np.setMinValue(0);   //设置显示的第一个数据np.setMaxValue(city.length - 1);    //设置显示的最后一个数据

private void updateCitySelector() {    int oldMax = cityPicker.getMaxValue();    int newMax = mCitys.length - 1;    if(newMax > oldMax) {        cityPicker.setDisplayedValues(mCitys);        cityPicker.setMaxValue(newMax);    } else {        cityPicker.setMaxValue(newMax);        cityPicker.setDisplayedValues(mCitys);    }}

private void updateCitySelector() {    cityPicker.setDisplayedValues(null);    cityPicker.setMaxValue(mCitys.length - 1);    cityPicker.setDisplayedValues(mCitys);}