kotlin android天气预报 android天气预报代码

创建数据库和表：

为了让项目能够有更好的结构，这里需要在com.coolweather.app包下再新建几个包

其中：

activity包用于存放所有活动相关的代码

db包用于存放所有数据库相关的代码

model包用于存放所有模型相关的代码

receiver包用于存放所有广播接收器相关的代码

service包用于存放所有服务相关的代码

util包用于存放所有工具相关的代码

ADT帮我们自动生成的MainActivity和activity_main.xml文件就不需要了，这里直接将它们删除掉。

第一阶段：创建数据库和表

建立三张表：Province City County 分别用于存放省 市 县的各种数据信息

三张表的建表语句分别如下：

Province:
create table Province (
		id integer primary key autoincrement,
		province_name text,
		province_code text)

其中id是自增长主键，province_name表示省名，province_code表示省级代号。

City:
create table City (
		id integer primary key autoincrement,
		city_name text,
		city_code text,
		province_id integer)

其中id是自增长主键，city_name表示城市名，city_code表示市级代号，province_id是表City关联表Province的外键

County:
create table County (
		id integer primary key autoincrement,
		county_name text,
		county_code text,
		city_id integer)

其中id是自增长主键，county_name表示县名，county_code表示县级代号，city_id是表County关联表City的外键

下面将建表语句写入到代码中

在db包下新建一个CoolWeatherOpenHelper类，代码如下所示：

public class CoolWeatherOpenHelper extends SQLiteOpenHelper {
	
	/**
	 * 	Province表建表语句
	 */
	public static final String CREATE_PROVINCE = "create table Province ("
			+ "id integer primary key autoincrement, "
			+ "province_name text, "
			+ "province_code text)";
	
	/**
	 * 	City表建表语句
	 */
	public static final String CREATE_CITY = "create table City ("
			+ "id integer primary key autoincrement, "
			+ "city_name text, "
			+ "city_code text, "
			+ "province_id integer)";
	
	/**
	 * 	County表建表语句
	 */
	public static final String CREATE_COUNTY = "create table County ("
			+ "id integer primary key autoincrement, "
			+ "county_name text, "
			+ "county_code text, "
			+ "city_id integer)";
	
	public CoolWeatherOpenHelper(Context context, String name, CursorFactory factory, int version) {
		super(context, name, factory, version);
	}

	
	@Override
	public void onCreate(SQLiteDatabase db) {
		db.execSQL(CREATE_PROVINCE); // 创建Province表
		db.execSQL(CREATE_CITY); // 创建City表
		db.execSQL(CREATE_COUNTY); // 创建County表
	}
	
	

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

}

将三条建表语句定义成常量，然后在onCreate()方法中去执行创建。

另外，每张表在代码中最好能有一个对应的实体类，这样会非常方便于我们后续的开发工作

因此，在model包下新建一个Province类，代码如下所示：

public class Province {
	private int id;
	private String provinceName;
	private String provinceCode;
	
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}
	
	public String getProvinceName() {
		return provinceName;
	}
	
	public void setProvinceName(String provinceName) {
		this.provinceName = provinceName;
	}
	
	public String getProvinceCode() {
		return provinceCode;
	}
	
	public void setProvinceCode(String provinceCode) {
		this.provinceCode = provinceCode;
	}
	
}

接着在model包下新建一个City类，代码如下所示：

public class City {
	private int id;
	private String cityName;
	private String cityCode;
	private int provinceId;
	
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}
	
	public String getCityName() {
		return cityName;
	}
	
	public void setCityName(String cityName) {
		this.cityName = cityName;
	}
	
	public String getCityCode() {
		return cityCode;
	}
	
	public void setCityCode(String cityCode) {
		this.cityCode = cityCode;
	}
	
	public int getProvinceId() {
		return provinceId;
	}
	
	public void setProvinceId(int provinceId) {
		this.provinceId = provinceId;
	}
	
}

然后在model包下新建一个County类，代码如下所示：

public class County {
	private int id;
	private String countyName;
	private String countyCode;
	private int cityId;
	
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}
	
	public String getCountyName() {
		return countyName;
	}
	
	public void setCountyName(String countyName) {
		this.countyName = countyName;
	}
	
	public String getCountyCode() {
		return countyCode;
	}
	
	public void setCountyCode(String countyCode) {
		this.countyCode = countyCode;
	}
	
	public int getCityId() {
		return cityId;
	}
	
	public void setCityId(int cityId) {
		this.cityId = cityId;
	}
	
}

接下来我们创建一个CoolWeatherDB类，这个类将一些常用的数据库操作封装起来。

public class CoolWeatherDB {

	/**
	 *  数据库名
	 */
	public static final String DB_NAME = "cool_weather";
	
	/**
	 * 	数据库版本
	 */
	public static final int VERSION = 1;
	
	private static CoolWeatherDB coolWeatherDB;
	
	private SQLiteDatabase db;
	
	/**
	 * 	将构造方法私有化
	 */
	private CoolWeatherDB(Context context) {
		CoolWeatherOpenHelper dbHelper = new CoolWeatherOpenHelper(context, DB_NAME, null, VERSION);
		db = dbHelper.getWritableDatabase();
	}
	
	/**
	 * 	获取CoolWeatherDB的实例
	 */
	public synchronized static CoolWeatherDB getInstance(Context context) {
		if (coolWeatherDB == null) {
			coolWeatherDB = new CoolWeatherDB(context);
		}
		return coolWeatherDB;
	}
	
	/**
	 * 	将Province实例存储到数据库
	 */
	public void saveProvince(Province province) {
		if (province != null) {
			ContentValues values = new ContentValues();
			values.put("province_name", province.getProvinceName());
			values.put("province_code", province.getProvinceCode());
			db.insert("Province", null, values);
		}
	}
	
	/**
	 * 	从数据库读取全国所有的省份信息
	 */
	public List<Province> loadProvinces() {
		List<Province> list = new ArrayList<Province>();
		Cursor cursor = db.query("Province", null, null, null, null, null, null);
		if (cursor.moveToFirst()) {
			do {
				Province province = new Province();
				province.setId(cursor.getInt(cursor.getColumnIndex("id")));
				province.setProvinceName(cursor.getString(cursor.getColumnIndex("province_name")));
				province.setProvinceCode(cursor.getString(cursor.getColumnIndex("province_code")));
				list.add(province);
			} while (cursor.moveToNext());
		}
		if (cursor != null) {
			cursor.close();
		}
		return list;
	}
	
	/**
	 * 	将City实例存储到数据库
	 */
	public void saveCity(City city) {
		if (city != null) {
			ContentValues values = new ContentValues();
			values.put("city_name", city.getCityName());
			values.put("city_code", city.getCityCode());
			values.put("province_id", city.getProvinceId());
			db.insert("City", null, values);
		}
	}
	
	/**
	 * 	从数据库读取某省下所有的城市信息
	 */
	public List<City> loadCities(int provinceId) {
		List<City> list = new ArrayList<City>();
		Cursor cursor = db.query("City", null, "province_id = ?", new String[] { String.valueOf(provinceId) }, null, null, null);
		if (cursor.moveToFirst()) {
			do {
				City city = new City();
				city.setId(cursor.getInt(cursor.getColumnIndex("id")));
				city.setCityName(cursor.getString(cursor.getColumnIndex("city_name")));
				city.setCityCode(cursor.getString(cursor.getColumnIndex("city_code")));
				list.add(city);
			} while (cursor.moveToNext());
		}
		if (cursor != null) {
			cursor.close();
		}
		return list;
	}
	
	/**
	 * 	将County实例存储到数据库
	 */
	public void saveCounty(County county) {
		if (county != null) {
			ContentValues values = new ContentValues();
			values.put("county_name", county.getCountyName());
			values.put("county_code", county.getCountyCode());
			values.put("city_id", county.getCityId());
			db.insert("County", null, values);
		}
	}
	
	/**
	 * 	从数据库读取某城市下所有的县信息
	 */
	public List<County> loadCounties(int cityId) {
		List<County> list = new ArrayList<County>();
		Cursor cursor = db.query("County", null, "city_id = ?", new String[] { String.valueOf(cityId) } , null, null, null);
		if (cursor.moveToFirst()) {
			do {
				County county = new County();
				county.setId(cursor.getInt(cursor.getColumnIndex("id")));
				county.setCountyName(cursor.getString(cursor.getColumnIndex("county_name")));
				county.setCountyCode(cursor.getString(cursor.getColumnIndex("county_code")));
				county.setCityId(cityId);
				list.add(county);
			} while (cursor.moveToNext());
		}
		if (cursor != null) {
			cursor.close();
		}
		return list;
	}
	
}

CoolWeatherDB是一个单例类，我们将它的构造函数私有化，并提供了一个getInstance()方法来获取CoolWeatherDB的实例，这样可以保证全局范围内只会有一个CoolWeatherDB实例。

最后附上GitHub：

https://github.com/LiuchangDuan/coolweather