使用Switch,减少圈复杂度java [英] Struck with Switch, reducing cyclomatic complexity java
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问题描述
使用java时我遇到了一个奇怪的情况,让我们先从代码开始。
while working with java i was stuck in a weird situation, lets start with code first.
public static String constructMessage(final String reason, final String xId,
final String yId, final IonStruct metadataStruct) throws DataSanityException {
String message = "";
switch (reason) {
case "NOT_ACTIVE":
if (xId != null) {
message = String.format("Y %s X %s not active: status is inactive%n", yId, xId);
} else {
message = String.format("Y %s not active: status is inactive%n", yId);
}
break;
case "PRICE_GONE":
if (metadataStruct.containsKey("applied")) {
final String applied = metadataStruct.get("applied");
if (applied.equals("single")) {
message = String.format("X %s is not active. price for the X is gone. "
+ "Y price %s for an X should not be gone by %s.%n", xId,
metadataStruct.get("yPrice"), metadataStruct.get("zPrice"));
} else {
if (metadataStruct.get("gonePeriod").equals("gonegone")) {
message = String.format("Y price is %s whereas the gone price is %s."
+ " Y price for an X should be at least %s%% lower than gone.%n",
metadataStruct.get(yPrice), metadataStruct.get(zPrice), metadataStruct.get("xyzPrice"));
} else {
message = String.format("Y price %s for an X should be at least %s%% lower than gone price %s in last %s days.%n",
metadataStruct.get(yPrice), metadataStruct.get("mpqPrice"), metadataStruct.get(lpzPrice),
metadataStruct.get("numberOfDays"));
}
}
} else {
message = String.format(
"X %s in Y %s is not active. is %s%%, min mpux is %s%%. ", xId,
yId, metadataStruct.get("lpux"), metadataStruct.get("mpxPrice"));
}
break;
and so on ----------- around 20 cases.
default:
message = "";
break;
}
在整个交换机中有20个这样的情况,具有不同的消息和不同的变量用于每个案例。
在一些开关中ifs的深度也达到3。
there are 20 cases like this in the complete switch with different messages and different variables used in each of the cases. And the depth of ifs is also upto 3 in some of the switches.
因此圈复杂度将达到29(太高),所以我想要重构具有低圈复杂度和更好可读性的代码。
So the cyclomatic complexity is coming 29(too high), so i want to refactor the code with low cyclomatic complexity and better readability.
任何建议?
推荐答案
来自Martin Fowler的重构书
From Martin Fowler's Refactoring book
我可以建议以下重构方法:
I can suggest following refactoring method:
import java.util.HashMap;
import java.util.Map;
public class Refactoring {
private static class IonStruct {};
private static interface MessageBuilder {
String build(final String xId,final String yId, final IonStruct metadataStruct);
}
private static class NotActiveMessageBuilder implements MessageBuilder {
private static final String YX_NON_ACTIVE_FMT = "Y %s X %s not active: status is inactive%n;";
private static final String Y_NON_ACTIVE_FMT = "Y %s not active: status is inactive%n";
@Override
public String build(String xId, String yId, IonStruct metadataStruct) {
return (xId != null) ? String.format(YX_NON_ACTIVE_FMT, yId, xId) : String.format(Y_NON_ACTIVE_FMT, yId) ;
}
}
private static enum MessageTypeChine
{
instance();
private final Map<String,MessageBuilder> builders;
private MessageTypeChine() {
this.builders = new HashMap<>();
this.builders.put("NOT_ACTIVE", new NotActiveMessageBuilder());
}
public String constructMessage(final String reason, final String xId,
final String yId, final IonStruct metadataStruct) {
MessageBuilder builder = this.builders.get(reason);
if(null != builder)
return builder.build(xId, yId, metadataStruct);
throw new UnsupportedOperationException("Message type is not supported");
}
}
public static String constructMessage(final String reason, final String xId,
final String yId, final IonStruct metadataStruct) {
return MessageTypeChine.instance.constructMessage(reason, xId, yId, metadataStruct);
}
}
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