面向对象系统分析与设计观察者模式.pptVIP

Neusoft Computer Science and Technology Department copy right Neusoft Computer Science and Technology Department copy right * Neusoft Computer Science and Technology Department copy right * OO System Analysis Design 【The Observer Pattern】 * Neusoft Computer Science and Technology Department copy right * Weather Monitoring overview Stats Forecast Current pulls data WeatherData object displays Weather Station Our client provides What we implement internet * Neusoft Computer Science and Technology Department copy right * What is WeatherData object? It knows how to talk to the physical Weather Station, to get updated data. (we don’t care for this process.) It then updates its displays for the three different display elements. gets data updates 它提供了三个方法(get开头)，可以分别取得实时的温度、湿度和大气压力，还有一个MeasurementsChanged()方法，当任何天气状况发生变化的时候，这个方法都会自动被触发，当前这个方法只是一个空函数，扩展的代码还需要我们自己去扩充。 * Neusoft Computer Science and Technology Department copy right * 1． 客户提供了获取实时的天气状况的方法 2． MeasurementsChanged()方法会在天气状况变化时被自动调用。 3． 系统要实现三种显示模式，分别显示天气状况、天气统计和天气预测，而且这些显示的信息必须跟当前必威体育精装版的天气状况实时同步。 4． 系统还必须支持在显示方式上的扩展性，而且使用者可以任意添加和移除不同的显示模式。 * Neusoft Computer Science and Technology Department copy right * //伪代码 public class WeatherData { //实例化显示设备(省略) public void MeasurementsChanged() { float temp = getTemperature(); //取得温度 float humidity = getHumidity(); //取得湿度 float pressure = getPressure(); //取得气压 currentConditionsDisplay.update(temp, humidity, pressure); //同步显示当前天气状况 statisticsDisplay.update(temp, humidity, pressure); //同步显示天气统计信息 forecastDisplay.update(temp, humidity, pressure); //同步显示天气预报信息 } } * Neusoft Computer Science and Technology Department copy right * * Neusoft Computer Science and Technology Department copy right * Our job is: To create an app that uses the WheatherData object to update three displays. * Neusoft Computer Science and Technology Department copy right * The kernel of the problem WeatherData object to update if you require displays publishers subscribers to deliver if you su