今天就跟大家聊聊有关如何理解Ribbon中的ServerList，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。
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ServerList是存数服务实例的对象。
public interface ServerList {
public List getInitialListOfServers();
/**
* Return updated list of servers. This is called say every 30 secs
* (configurable) by the Loadbalancer's Ping cycle
*
*/
public List getUpdatedListOfServers();
}
通过静态配置来维护服务列表。
public class StaticServerList implements ServerList {
private final List servers;
public StaticServerList(T... servers) {
this.servers = Arrays.asList(servers);
}
@Override
public List getInitialListOfServers() {
return servers;
}
@Override
public List getUpdatedListOfServers() {
return servers;
}
}
ServerList拦截器,被LoadBalancer使用。
public abstract class AbstractServerList implements ServerList, IClientConfigAware {
/**
* Get a ServerListFilter instance. It uses {@link ClientFactory#instantiateInstanceWithClientConfig(String, IClientConfig)}
* which in turn uses reflection to initialize the filter instance.
* The filter class name is determined by the value of {@link CommonClientConfigKey#NIWSServerListFilterClassName}
* in the {@link IClientConfig}. The default implementation is {@link ZoneAffinityServerListFilter}.
*/
public AbstractServerListFilter getFilterImpl(IClientConfig niwsClientConfig) throws ClientException{
try {
String niwsServerListFilterClassName = niwsClientConfig
.getProperty(
CommonClientConfigKey.NIWSServerListFilterClassName,
ZoneAffinityServerListFilter.class.getName())
.toString();
AbstractServerListFilter abstractNIWSServerListFilter =
(AbstractServerListFilter) ClientFactory.instantiateInstanceWithClientConfig(niwsServerListFilterClassName, niwsClientConfig);
return abstractNIWSServerListFilter;
} catch (Throwable e) {
throw new ClientException(
ClientException.ErrorType.CONFIGURATION,
"Unable to get an instance of CommonClientConfigKey.NIWSServerListFilterClassName. Configured class:"
+ niwsClientConfig
.getProperty(CommonClientConfigKey.NIWSServerListFilterClassName), e);
}
}
}
通过配置文件参数listOfservers,来实现ServerList.多个用逗号分隔。
public class ConfigurationBasedServerList extends AbstractServerList {
private IClientConfig clientConfig;
@Override
public List getInitialListOfServers() {
return getUpdatedListOfServers();
}
@Override
public List getUpdatedListOfServers() {
String listOfServers = clientConfig.get(CommonClientConfigKey.ListOfServers);
return derive(listOfServers);
}
@Override
public void initWithNiwsConfig(IClientConfig clientConfig) {
this.clientConfig = clientConfig;
}
protected List derive(String value) {
List list = Lists.newArrayList();
if (!Strings.isNullOrEmpty(value)) {
for (String s: value.split(",")) {
list.add(new Server(s.trim()));
}
}
return list;
}
}
通过Eureka的服务发现，实现的ServerList.
public class DiscoveryEnabledNIWSServerList extends AbstractServerList{
@Override
public List getInitialListOfServers(){
return obtainServersViaDiscovery();
}
@Override
public List getUpdatedListOfServers(){
return obtainServersViaDiscovery();
}
private List obtainServersViaDiscovery() {
List serverList = new ArrayList();
if (eurekaClientProvider == null || eurekaClientProvider.get() == null) {
logger.warn("EurekaClient has not been initialized yet, returning an empty list");
return new ArrayList();
}
EurekaClient eurekaClient = eurekaClientProvider.get();
if (vipAddresses!=null){
for (String vipAddress : vipAddresses.split(",")) {
// if targetRegion is null, it will be interpreted as the same region of client
List listOfInstanceInfo = eurekaClient.getInstancesByVipAddress(vipAddress, isSecure, targetRegion);
for (InstanceInfo ii : listOfInstanceInfo) {
if (ii.getStatus().equals(InstanceStatus.UP)) {
if(shouldUseOverridePort){
if(logger.isDebugEnabled()){
logger.debug("Overriding port on client name: " + clientName + " to " + overridePort);
}
// copy is necessary since the InstanceInfo builder just uses the original reference,
// and we don't want to corrupt the global eureka copy of the object which may be
// used by other clients in our system
InstanceInfo copy = new InstanceInfo(ii);
if(isSecure){
ii = new InstanceInfo.Builder(copy).setSecurePort(overridePort).build();
}else{
ii = new InstanceInfo.Builder(copy).setPort(overridePort).build();
}
}
DiscoveryEnabledServer des = new DiscoveryEnabledServer(ii, isSecure, shouldUseIpAddr);
des.setZone(DiscoveryClient.getZone(ii));
serverList.add(des);
}
}
if (serverList.size()>0 && prioritizeVipAddressBasedServers){
break; // if the current vipAddress has servers, we dont use subsequent vipAddress based servers
}
}
}
return serverList;
}
}
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