我有两个环境PROD
和STAGING
。在prod环境中,我们有三个数据中心ABC
,DEF
和PQR
,并且升级有一个数据中心CORP
。每个数据中心都有很少的机器,我为它们定义了常量,如下所示:
// NOTE: I can have more machines in each dc in future
public static final ImmutableList<String> ABC_SERVERS = ImmutableList.of("tcp://machineA:8081", "tcp://machineA:8082");
public static final ImmutableList<String> DEF_SERVERS = ImmutableList.of("tcp://machineB:8081", "tcp://machineB:8082");
public static final ImmutableList<String> PQR_SERVERS = ImmutableList.of("tcp://machineC:8081", "tcp://machineC:8082");
public static final ImmutableList<String> STAGING_SERVERS = ImmutableList.of("tcp://machineJ:8087","tcp://machineJ:8088");
现在我在同一个类中定义了另一个常量,它按DC分组到每个环境类型的机器列表。
public static final ImmutableMap<Datacenter, ImmutableList<String>> PROD_SERVERS_BY_DC =
ImmutableMap.<Datacenter, ImmutableList<String>>builder()
.put(Datacenter.ABC, ABC_SERVERS).put(Datacenter.DEF, DEF_SERVERS)
.put(Datacenter.PQR, PQR_SERVERS).build();
public static final ImmutableMap<Datacenter, ImmutableList<String>> STAGING_SERVERS_BY_DC =
ImmutableMap.<Datacenter, ImmutableList<String>>builder()
.put(Datacenter.CORP, STAGING_SERVERS).build();
现在在其他一些课程中,基于我在(Utils.isProd())
的环境,我得到PROD_SERVERS_BY_DC
或STAGING_SERVERS_BY_DC
。
Map<Datacenter, ImmutableList<String>> machinesByDC = Utils.isProd() ? Utils.PROD_SERVERS_BY_DC : Utils.STAGING_SERVERS_BY_DC;
现在我认为这可以用某种Enum更好的方式表示,而不是像我上面那样定义常量,但我无法弄清楚我该怎么做?我开始讨论这个但是混淆了如何为每个DC提供单个密钥,然后将多个值作为该DC的机器列表,然后我还需要按环境对它们进行分组。
// got confuse on how can I make key (DC) and list of values (machines) for each environment type.
public enum DCToMachines {
abc(tcp://machineA:8081", "tcp://machineA:8082"),
private final List<String> machines;
private final Datacenter datacenter;
...
}
我开始讨论这个但是混淆了如何为每个DC提供单个密钥,然后将多个值作为该DC的机器列表,然后我还需要按环境对它们进行分组。
你忘记了一个重要的因素:枚举可以存储特定于每个枚举值的成员(方法和字段),但如果需要,它也可以存储static
成员。
您需要的是直接在枚举类中移动按环境分组的地图:
private static final ImmutableMap<Datacenter, ImmutableList<String>> PROD_SERVERS_BY_DC;
private static final ImmutableMap<Datacenter, ImmutableList<String>> STAGING_SERVERS_BY_DC;
您可以使用内部地图根据用户请求返回预期的地图:
private static final Map<Env, ImmutableMap<Datacenter, ImmutableList<String>>> SERVERS_BY_ENV;
Env
是另一个枚举:
public static enum Env {
PROD, STAGING
}
在我将要呈现的代码中,我添加了一个封闭类型的Datacenter
,但它在自己的文件中可能更好,因为环境可能不是数据中心专用的概念。
最后,您通过环境检索服务器的方式将相关职责分为2个类(Datacenter
枚举和当前类):
Map<Datacenter, ImmutableList<String>> machinesByDC = Utils.isProd() ? Utils.PROD_SERVERS_BY_DC : Utils.STAGING_SERVERS_BY_DC;
在枚举中引入一个方法来执行此操作会更好:
public static ImmutableMap<Datacenter, ImmutableList<String>> getServers(Env env){...}
这将增加枚举类的凝聚力。
这是更新的枚举:
import java.util.HashMap;
import java.util.Map;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMap.Builder;
public enum Datacenter {
ABC(Env.PROD, "tcp://machineA:8081", "tcp://machineA:8082"),
DEF(Env.PROD, "tcp://machineB:8081", "tcp://machineB:8082"),
PQR(Env.PROD, "tcp://machineA:8081", "tcp://machineA:8082"),
CORP(Env.STAGING, "tcp://machineC:8081", "tcp://machineC:8082");
public static enum Env {
PROD, STAGING
}
private Env env;
private String[] url;
private static final ImmutableMap<Datacenter, ImmutableList<String>> PROD_SERVERS_BY_DC;
private static final ImmutableMap<Datacenter, ImmutableList<String>> STAGING_SERVERS_BY_DC;
private static final Map<Env, ImmutableMap<Datacenter, ImmutableList<String>>> SERVERS_BY_ENV;
static {
Builder<Datacenter, ImmutableList<String>> prodDataCenterBuilder = ImmutableMap.<Datacenter, ImmutableList<String>>builder();
Builder<Datacenter, ImmutableList<String>> stagingDataCenterBuilder = ImmutableMap.<Datacenter, ImmutableList<String>>builder();
for (Datacenter datacenter : Datacenter.values()) {
if (datacenter.env == Env.PROD) {
prodDataCenterBuilder.put(datacenter, ImmutableList.of(datacenter.url));
} else if (datacenter.env == Env.STAGING) {
stagingDataCenterBuilder.put(datacenter, ImmutableList.of(datacenter.url));
}
else {
throw new IllegalArgumentException("not exepected env " + datacenter.env);
}
}
PROD_SERVERS_BY_DC = prodDataCenterBuilder.build();
STAGING_SERVERS_BY_DC = stagingDataCenterBuilder.build();
SERVERS_BY_ENV = new HashMap<>();
SERVERS_BY_ENV.put(Env.PROD, PROD_SERVERS_BY_DC);
SERVERS_BY_ENV.put(Env.STAGING, STAGING_SERVERS_BY_DC);
}
Datacenter(Env env, String... url) {
this.env = env;
this.url = url;
}
public static ImmutableMap<Datacenter, ImmutableList<String>> getServers(Env env) {
ImmutableMap<Datacenter, ImmutableList<String>> map = SERVERS_BY_ENV.get(env);
if (map == null) {
throw new IllegalArgumentException("not exepected env " + env);
}
return map;
}
}
在这里如何使用它:
public static void main(String[] args) {
ImmutableMap<Datacenter, ImmutableList<String>> servers = Datacenter.getServers(Env.PROD);
servers.forEach((k, v) -> System.out.println("prod datacenter=" + k + ", urls=" + v));
servers = Datacenter.getServers(Env.STAGING);
servers.forEach((k, v) -> System.out.println("staging datacenter=" + k + ", urls=" + v));
}
输出:
prod datacenter = ABC,urls = [tcp:// machineA:8081,tcp:// machineA:8082]
prod datacenter = DEF,urls = [tcp:// machineB:8081,tcp:// machineB:8082]
prod datacenter = PQR,urls = [tcp:// machineA:8081,tcp:// machineA:8082]
staging data center = CORP,urls = [tcp:// machine:8081,tcp:// machine:8082]
虽然在不知道完全实现的情况下这有点棘手,但我可以帮助您入门。
枚举很有意思,因为它们是不可变的,它解决了声明常量字段和变量的问题。这是我尝试解决您正在寻找的问题。
public enum Server {
// Constant style naming because Enums are Immutable objects
ABC_SERVERS("tcp://machineA:8081", "tcp://machineA:8082"),
DEF_SERVERS("tcp://machineB:8081", "tcp://machineB:8082"),
PQR_SERVERS("tcp://machineC:8081", "tcp://machineC:8082"),
CORP("tcp://machineZ:8081");
/* After the name declaration you can essentially do normal class
development
*/ Fields
private List<String> servers = new ArrayList<>();
public boolean isProd; // you could use something as simple as a
//boolean to determine the environment
// Enums use a private constructor because they are never
//instantiated outside of creation of this Enum class
private Server(String... dataCenter){
// because of the varargs parameter there is a potential for
//multiple Strings to be passed
for (String tcp :
dataCenter) {
this.servers.add(tcp);
}
// You can access the name property of the Enum that is being created
if (this.name() == "CORP")
this.isProd = false;
else
this.isProd = true;
}
// You could make the List public but this demonstrates some encapsulation
public List<String> getServers() {
return servers;
}
}
然后我检查了每个“机器”是否正在另一个类中添加
// these are what I used to check to make sure that each string is being "mapped" correctly
List<String> prodServer = new ArrayList<>();
List<String> stagingServer = new ArrayList<>();
for (Server server :
Server.values()) {
if (server.isProd) {
for (String machine :
server.getServers()) {
prodServer.add(machine);
}
}
else {
for (String machine:
server.getServers()) {
stagingServer.add(machine);
}
}
}
System.out.println(prodServer);
System.out.println(stagingServer);
另请注意,要获取实际的枚举名称,请使用Enum类的.values()函数。