java简单工程模式

实现一个计算器

1.新建计算类

  
public class Operation {
	private double _numa;
	private double _numb;
	private double _result;

	/**
	 * 获取_numa
	 * 
	 * @return _numa
	 */

	public double get_numa() {
		return _numa;
	}

	/**
	 * 设置_numa
	 * 
	 * @param _numa
	 */
	public void set_numa(double _numa) {
		this._numa = _numa;
	}

	/**
	 * 获取_numb
	 * 
	 * @return _numb
	 */

	public double get_numb() {
		return _numb;
	}

	/**
	 * 设置_numb
	 * 
	 * @param _numb
	 */
	public void set_numb(double _numb) {
		this._numb = _numb;
	}

	/**
	 * 获取_result
	 * 
	 * @return _result
	 */

	public double get_result() {
		return _result;
	}

	/**
	 * 设置_result
	 * 
	 * @param _result
	 */
	public void set_result(double _result) {
		this._result = _result;
	}
}

2.新建一个加法类继承OpetationAdd并重写get_result()方法

  
public class OperationFactory {
	/**
	 * 创建运算类
	 */
	public static Operation createOperation(String operator) {
		Operation operation = null;
		switch (operator) {
		case "+":
			operation = new OperationAdd();
			break;

		default:
			break;
		}
		return operation;
	}

	/**
	 * 描述方法的作用
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		Operation op = new OperationFactory().createOperation("+");
		op.set_numa(2);
		op.set_numb(2);
		System.out.println(op.get_result());
	}

}
3.新建OperationFactory类并新建createOperation()方法实现抽象运算

  
public class OperationFactory {
	/**
	 * 创建运算类
	 */
	public static Operation createOperation(String operator) {
		Operation operation = null;
		switch (operator) {
		case "+":
			operation = new OperationAdd();
			break;

		default:
			break;
		}
		return operation;
	}

	

}
4.测试运行加法

  
/**
	 * 描述方法的作用
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		Operation op = new OperationFactory().createOperation("+");
		op.set_numa(2);
		op.set_numb(2);
		System.out.println(op.get_result());
	}
以后需要修改加法只要修改OperationAdd类即可

如果需要添加其他复杂运算,只要添加相关类并在OperationFactory类的createOperation()方法中添加switch分支即可

Android SQLite使用demo

Android SQLite使用demo

1.建立dbhelper类:
Context context;
public static int DB_VERSION = 1;
public static String DB_NAME = "d_weather.db";
public static String TABLE_NAME = "t_weather";

/**
* 构造方法
*
* @param context
* @param name
* @param factory
* @param version
*/
public SQLiteDataHelp(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
// SQLiteOpenHelper子类必须要的一个构造函数
}

/**
* 构造方法
*/
public SQLiteDataHelp(Context context) {
// 必须实现父类构造方法
this(context, DB_VERSION);
}

public SQLiteDataHelp(Context context, int version) {
// 必须实现父类构造方法
this(context, DB_NAME, null, DB_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
// 数据库初始化
db.execSQL("create table if not exists " + TABLE_NAME + "("
+ "w_id integer primary key," + "w_name varchar,"
+ "w_temp varchar)");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// 当打开数据库时传入的版本号与当前的版本号不同时会调用该方法

}

public void insert(ContentValues contentValues) {
SQLiteDatabase db = getWritableDatabase();
db.insert(TABLE_NAME, null, contentValues);
db.close();
}

/**
*
* query
*
* @return
*/
public Cursor query() {
SQLiteDatabase db = getReadableDatabase();
// 获取Cursor
Cursor c = db.query(TABLE_NAME, null, null, null, null, null, null,
null);
return c;
}

//更新数据库的内容
public void update(ContentValues values, String whereClause, String[]whereArgs){
   SQLiteDatabase db = getWritableDatabase();
   db.update(TABLE_NAME, values, whereClause, whereArgs);
}

// 根据唯一标识_id 来删除数据
public void delete(int id) {
SQLiteDatabase db = getWritableDatabase();
db.delete(TABLE_NAME, "w_id=?", new String[] { String.valueOf(id) });
}

2.调用CRUD方法:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// CRUD操作
// insert
SQLiteDataHelp dbhelp = new SQLiteDataHelp(MainActivity.this);
ContentValues contentValues = new ContentValues();
contentValues.put("w_name", "北京");
contentValues.put("w_temp", "22°C");
// dbhelp.insert(contentValues);
// delete
// dbhelp.delete(1);
// 修改
dbhelp.update(contentValues, "w_name='北京'", null);
// 查询
Cursor cursor = dbhelp.query();
if (cursor.getCount() == 0) {
GlobalConstant.i("no data!!");
} else {
while (cursor.moveToNext()) {
GlobalConstant.i("w_id--->"
+ cursor.getInt(cursor.getColumnIndex("w_id")));
GlobalConstant.i("w_name--->"
+ cursor.getString(cursor.getColumnIndex("w_name")));
GlobalConstant.i("w_temp--->"
+ cursor.getString(cursor.getColumnIndex("w_temp")));
GlobalConstant.i("-----------------");
}
}
}