java在验证检查中改进构建器模式?
我最近开始在我的一个项目中使用Builder模式,我正在尝试在我的Builder类上添加某种验证。我假设我们不能在编译时进行验证,所以我在运行时进行验证。但可能是我错了,这就是我想看看我是否能在编译时做到这一点的原因
public final class RequestKey {
private final Long userid;
private final String deviceid;
private final String flowid;
private final int clientid;
private final long timeout;
private final boolean abcFlag;
private final boolean defFlag;
private final Map<String, String> baseMap;
private RequestKey(Builder builder) {
this.userid = builder.userid;
this.deviceid = builder.deviceid;
this.flowid = builder.flowid;
this.clientid = builder.clientid;
this.abcFlag = builder.abcFlag;
this.defFlag = builder.defFlag;
this.baseMap = builder.baseMap.build();
this.timeout = builder.timeout;
}
public static class Builder {
protected final int clientid;
protected Long userid = null;
protected String deviceid = null;
protected String flowid = null;
protected long timeout = 200L;
protected boolean abcFlag = false;
protected boolean defFlag = true;
protected ImmutableMap.Builder<String, String> baseMap = ImmutableMap.builder();
public Builder(int clientid) {
checkArgument(clientid > 0, "clientid must not be negative or zero");
this.clientid = clientid;
}
public Builder setUserId(long userid) {
checkArgument(userid > 0, "userid must not be negative or zero");
this.userid = Long.valueOf(userid);
return this;
}
public Builder setDeviceId(String deviceid) {
checkNotNull(deviceid, "deviceid cannot be null");
checkArgument(deviceid.length() > 0, "deviceid can't be an empty string");
this.deviceid = deviceid;
return this;
}
public Builder setFlowId(String flowid) {
checkNotNull(flowid, "flowid cannot be null");
checkArgument(flowid.length() > 0, "flowid can't be an empty string");
this.flowid = flowid;
return this;
}
public Builder baseMap(Map<String, String> baseMap) {
checkNotNull(baseMap, "baseMap cannot be null");
this.baseMap.putAll(baseMap);
return this;
}
public Builder abcFlag(boolean abcFlag) {
this.abcFlag = abcFlag;
return this;
}
public Builder defFlag(boolean defFlag) {
this.defFlag = defFlag;
return this;
}
public Builder addTimeout(long timeout) {
checkArgument(timeout > 0, "timeout must not be negative or zero");
this.timeout = timeout;
return this;
}
public RequestKey build() {
if (!this.isValid()) {
throw new IllegalStateException("You have to pass at least one"
+ " of the following: userid, flowid or deviceid");
}
return new RequestKey(this);
}
private boolean isValid() {
return !(TestUtils.isEmpty(userid) && TestUtils.isEmpty(flowid) && TestUtils.isEmpty(deviceid));
}
}
// getters here
}
问题陈述:
在我上面的构建器模式中,只有一个参数是必需的clientId
,其余的参数是可选的,但我需要设置userid
、flowid
或deviceid
。如果这三个都没有设置,那么我将抛出带有错误消息的IllegalStateException
,如代码中所示。我在运行时进行的检查。如果可能的话,我想在编译时做这个检查,除非提供了所有内容,否则不要构建我的模式
不是强制要求他们每次都要通过所有这三个id,他们可以通过所有三个,有时两个,有时只有一个,但条件是应该设置其中一个
如何改进构建器模式,以便只在编译时进行id验证,而不是在运行时进行id验证
我发现这个SOlink确切地说是关于同一件事,但不确定如何在我的场景中使用它?还有这个{a2}和这个{a3}
有人能举个例子吗?我如何在我的构建器模式中解决这个问题
# 1 楼答案
仅当设置了必需的属性时,才使
build
方法可访问:输出: