使用枚举 Enum 来减少 if else，快来看看适不适合你吧？

1. 场景

当我需要调用其他其他接口，这个接口某个参数需要根据不同情况来传递不同的固定值
如：B接口调用A接口，A接口中需要传递授权码，这个授权码在不同的业务场景不同的手机系统需要传递不同的值，普通的传值方式如下：

public void notEnum(Request req){
	TestReq testReq = new TestReq();//A接口的请求

	if("android".equals(req.getSysType())){
		if("a".equals(req.getBusinessType())){
			testReq.setSign("android_aaaaaaaaaaa");
		}else if("b".equals(req.getBusinessType())){
			testReq.setSign("android_bbbbbbbbbbb");
		}else if("c".equals(req.getBusinessType())){
			testReq.setSign("android_ccccccccccc");
		}
	}else if("ios".equals(req.sysType)){
		if("a".equals(req.getBusinessType())){
			testReq.setSign("ios_aaaaaaaaaaa");
		}else if("b".equals(req.getBusinessType())){
			testReq.setSign("ios_bbbbbbbbbbb");
		}else if("c".equals(req.getBusinessType())){
			testReq.setSign("ios_ccccccccccc");
		}
	}
	
}

17行 if else 看着贼&*¥#@难受！我就赋个值而已！而且值还是死的。

2.优化

定义enum：

public enum TestEnum{
	A_ANDROID("a","android","android_aaaaaaaaaaa"),
	A_IOS("a","ios","ios_aaaaaaaaaaa"),
	B_ANDROID("b","android","android_bbbbbbbbbbb"),
	B_IOS("b","ios","ios_bbbbbbbbbbb"),
	C_ANDROID("c","android","android_ccccccccccc"),
	C_IOS("c","ios","ios_ccccccccccc");

	private String type;
	private String source;
	private String code;

	TestEnum(String type,String source,String code){
		this.type = type;
		this.source = source;
		this.code = code;
	}

	public static String getCodeByTypeAndSource(String type,String source){
		TestEnum[] enums = TestEnum.values();
		for(TestEnum item : enums){
			if(item.type.equals(type)&&item.source.equals(source)){
				return item.code;
			}
		}
	}

}

简化后的代码：

public void useEnum(Request req){
	TestReq testReq = new TestReq();//A接口的请求
	testReq.setSign(TestEnum.getCodeByTypeAndSource(req.getBusinessType(),req.getSysType());
		
}