避免过多if-else的几种方法

String input = "three";

@Test
public void testElse() {
    if ("one".equals(input)) {
        System.out.println("one");
    } else if ("two".equals(input)) {
        System.out.println("two");
    } else if ("three".equals(input)) {
        System.out.println("three");
    } else if ("four".equals(input)) {
        System.out.println("four");
    }
}

代码中一堆 if else
看起来 就 不舒服,不美观，又长

方法一 迭代模式

public interface INotification {

    String getType();

    void execute(String title ,String content);

}

public class WeChatNotification implements INotification {

    static Pattern pWeixin = Pattern.compile("微信支付收款([\\d\\.]+)元");

    @Override
    public String getType() {
        return Common.WECHAT_PACKAGE;
    }

    @Override
    public void execute(String title ,String content) {
         //TODO 
        }

    }
}

初始化

private List<INotification> handlerList = new ArrayList<>();

       handlerList.add(new AlipayNotification());
       handlerList.add(new ECardPayNotification());
       handlerList.add(new GuiZhouBankNotification());
       handlerList.add(new SPayNotification());
       handlerList.add(new WeChatNotification());
       handlerList.add(new XingGuanJiaNotification());
       handlerList.add(new ZhongYingBankNotification());

使用 迭代

for(INotification handler:handlerList){
        if( handler.getType().contains(pkgName) ){
            handler.execute(title,content);
        }
    }

这边也可以使用map
map 效率比list 高

方法一 工厂模式

public interface INotification {

    String getType();

    void execute(String title ,String content);

}

public class NotificationFactory {

    public static INotification createMessage(String messageType) {

        switch (messageType) {
            case Common.e_card_PKG:
                return new ECardPayNotification();

            case Common.xiaomi_PKG:
            case Common.guizhou_PKG:
                return new GuiZhouBankNotification();

            case Common.laijucai_PKG:
                return new ZhongYingBankNotification();

            case Common.SPay_PKG:
                return new SPayNotification();

            case Common.xingGuanjia_PKG:
                return new XingGuanJiaNotification();

            case Common.WECHAT_PACKAGE:
                return new WeChatNotification();

            case Common.ALIPAY_PACKAGE:
                return new AlipayNotification();
            default:
                return null;
        }
    }

}

使用

INotification mNotification = NotificationFactory.createMessage(pkgName);
if (null != mNotification) mNotification.execute(title, content);