java枚举在android项目应用

今天修复一个公司非常早曾经的android应用功能，里面的代码逻辑已经全然错乱，然后发现返回的数据全然不正确了。然后修复了整整两天。然后我又一次整理了一遍，重构就算不上了。

然后就用上了枚举。

什么是枚举？我曾经也不懂，当时我看见公司的项目中使用了枚举当做项目一个控制，比方改动已经写好的app然后为一些手机厂商做定制版。可能要去掉广告，还有跳转到商店url都不同，特别是国内基本都没有google play。我们为了避免以后的改动。就会写个枚举来控制它。

public enum Market {
	
	Default,Huawei(){
		@Override
		public String getMarketUrl() {
			return "http://play.huawei.com";//huawei market url
		}
	},ZTE(){
		@Override
		public boolean isShouldAd(){
			return false;
		}
		@Override
		public String getMarketUrl() {
			return "http://play.zte.com";//ZTE market url
		}
	},OneTouch(){
		@Override
		public String getMarketUrl() {
			return "http://play.huawei.com";
		}
	};
	
	
	public boolean isShouldAd(){
		return true;
	}
	
	public String getMarketUrl(){
		return "http:\\googleplay....";//google play url
	}
}

通过上面的样例就大概了解了一些java枚举在android的基本使用。

为了了解java枚举的原理，我写了一个非经常常使用的红绿灯样例。以下是用枚举的代码：

public enum TrafficLight {

	red(45) {
		@Override
		public TrafficLight nextLamp() {
			return green;
		}
	},
	green(30) {
		@Override
		public TrafficLight nextLamp() {
			return yellow;
		}
	},
	yellow(3) {
		@Override
		public TrafficLight nextLamp() {
			return red;
		}
	};

	private int time;

	private TrafficLight(int time) {
		this.time = time;
	};

	public abstract TrafficLight nextLamp();

	public int getTime() {
		return this.time;
	}
}

public abstract class TrafficLight {
	

	public static final TrafficLight red  = new TrafficLight(45){
		@Override
		public TrafficLight nextLamp() {
			return green;
		}
	};
	public static final TrafficLight green  = new TrafficLight(30) {
		@Override
		public TrafficLight nextLamp() {
			return yellow;
		}
	};
	
	public static final TrafficLight yellow  = new TrafficLight(3) {
		@Override
		public TrafficLight nextLamp() {
			return red;
		}
	};

	private int time;

	private TrafficLight(int time) {
		this.time = time;
	};

	public abstract TrafficLight nextLamp();

	public int getTime() {
		return this.time;
	}
}

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

public enum RequestedProvider {

	mySelf() {
		@Override
		public String getUrl(String keyWord) {
			return "http://..." + keyWord + "...";
		}...
	},
	google() {
		@Override
		public String getUrl(String keyWord) {
			return "http://google..." + keyWord + "...";
		}...
	},
	amazon() {
		@Override
		public String getUrl(String keyWord) {
			return "http://amazon..." + keyWord + "...";
		}...
	};

	public abstract String getUrl(String keyWord);

	public HttpClient pickHttpClient() {
		return new DefaultHttpClient();
	}

	public HttpGet pickHttpGet(String url) {
		return new HttpGet(url);
	}

	public HttpResponse pickHttpResponse(HttpClient client, HttpGet get) {
		HttpResponse res = null;
		try {
			res = client.execute(get);
		} catch (ClientProtocolException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return res;
	}...

}