etcd 和zookeeper 很像，都可以用来做配置管理。并且etcd可以在目前流行的Kubernetes中使用。
但是etcd 提供了v2版本合v3的版本的两种api。我们现在分别来介绍一下这两个版本api的使用。
一、Etcd V2版本API
1、java工程中使用maven引入 etcd v2的java api操作jar包
<dependency><groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.21.Final</version>
</dependency> <dependency>
<groupId>org.mousio</groupId>
<artifactId>etcd4j</artifactId>
<version>2.15.0</version>
</dependency>
2、etcd的链接 import mousio.etcd4j.EtcdClient;
import java.io.InputStream;
import java.net.URI;
import java.util.Properties;
public class EtcdUtil {
//etcd客户端链接
private static EtcdClient client = null;
//链接初始化
public static synchronized EtcdClient getClient(){
if (null == client){
client = new EtcdClient (URI.create(properties.getProperty("http://127.0.0.1:2379")));
}
return client;
}
}
3、如何获取etcd的配置并且对配置进行监听
//初始化获取etcd配置并且进行配置监听 private void initEtcdConfig() {
EtcdKeysResponse dataTree ;
try {
final EtcdClient etcdClient = EtcdUtil.getClient();
//获取etcd中名称叫ETCD文件夹下的配置
EtcdKeyGetRequest etcdKeyGetRequest = etcdClient.getDir("ETCD").consistent();
dataTree = etcdKeyGetRequest.send().get();
//获取etcd的版本
System.out.println("ETCD's version:"+etcdClient.getVersion());
getConfig("/ETCD/example.config",dataTree); //加载配置项
//启动一个线程进行监听
startListenerThread(etcdClient);
} catch (Exception e) {
System.out.println("EtcdClient init cause Exception:"+e.getMessage());
e.printStackTrace();
}
} private String getConfig(String configFile,EtcdKeysResponse dataTree){
if(null != dataTree && dataTree.getNode().getNodes().size()>0){
for(EtcdKeysResponse.EtcdNode node:dataTree.getNode().getNodes()){
if(node.getKey().equals(configFile)){
return node.getValue();
}
}
}
System.out.println("Etcd configFile"+ configFile+"is not exist,Please Check");
return null;
} public void startListenerThread(EtcdClient etcdClient){
new Thread(()->{
startListener(etcdClient);
}).start();
}
public void startListener(EtcdClient etcdClient){
ResponsePromise promise =null;
try {
promise = etcdClient.getDir(SYSTEM_NAME).recursive().waitForChange().consistent().send();
promise.addListener(promisea -> {
logger.info("found ETCD's config:{}cause change",ETCD_CONFIG_FILE_NAME);
try {
getConfig("/ETCD/example.config", etcdClient.getDir("ETCD").consistent().send().get()); //加载配置项
} catch (Exception e) {
e.printStackTrace();
logger.info("listen etcd 's config change cause exception:{}",e.getMessage());
}
startListener(etcdClient);
});
} catch (Exception e) {
startListener(etcdClient);
System.out.println("listen etcd 's config change cause exception:"+e.getMessage());
e.printStackTrace();
}
}
4、使用dcmp管理 etcd的配置项 dcmp 是一个使用go语言开发的etcd配置界面，不足的时，这个只支持v2的API，项目的地址：
https://github.com/silenceper/dcmp
一、Etcd V3版本API
1、在工程引入如下依赖
<dependency><groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.15.Final</version>
</dependency>
<dependency>
<groupId>com.coreos</groupId>
<artifactId>jetcd-core</artifactId>
<version>0.0.2</version>
</dependency>
2、v3 api操作工具类 public class EtcdUtil {
//etcl客户端链接
private static Client client = null;
//链接初始化
public static synchronized Client getEtclClient(){
if(null == client){
client = Client.builder().endpoints(props.getProperty("http://127.0.0.1:2379")).build();
}
return client;
}
/**
* 根据指定的配置名称获取对应的value
* @param key 配置项
* @return
* @throws Exception
*/
public static String getEtcdValueByKey(String key) throws Exception {
List<KeyValue> kvs = EtcdUtil.getEtclClient().getKVClient().get(ByteSequence.fromString(key)).get().getKvs();
if(kvs.size()>0){
String value = kvs.get(0).getValue().toStringUtf8();
return value;
}
else {
return null;
}
}
/**
* 新增或者修改指定的配置
* @param key
* @param value
* @return
*/
public static void putEtcdValueByKey(String key,String value) throws Exception{
EtcdUtil.getEtclClient().getKVClient().put(ByteSequence.fromString(key),ByteSequence.fromBytes(value.getBytes("utf-8")));
}
/**
* 删除指定的配置
* @param key
* @return
*/
public static void deleteEtcdValueByKey(String key){
EtcdUtil.getEtclClient().getKVClient().delete(ByteSequence.fromString(key));
}
}
//V3 api配置初始化和监听
public void init(){ try {
//加载配置
getConfig(EtcdUtil.getEtclClient().getKVClient().get(ByteSequence.fromString(ETCD_CONFIG_FILE_NAME)).get().getKvs());
//启动监听线程
new Thread(() -> {
//对某一个配置进行监听
Watch.Watcher watcher = EtcdUtil.getEtclClient().getWatchClient().watch(ByteSequence.fromString("etcd_key"));
try {
while(true) {
watcher.listen().getEvents().stream().forEach(watchEvent -> {
KeyValue kv = watchEvent.getKeyValue();
//获取事件变化类型
System.out.println(watchEvent.getEventType());
//获取发生变化的key
System.out.println(kv.getKey().toStringUtf8()); //获取变化后的value
String afterChangeValue = kv.getValue().toStringUtf8();
});
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
} catch (Exception e) {
e.printStackTrace();
}
} private String getConfig(List<KeyValue> kvs){
if(kvs.size()>0){
String config = kvs.get(0).getValue().toStringUtf8();
logger.info("etcd 's config:{} 's configValue is :{}",ETCD_CONFIG_FILE_NAME,config);
return config;
}
else {
return null;
}
}