博客中代码地址：https://github.com/farliu/farpc.git
在上两章中，我们基于zookeeper实现了dubbo的注册中心。本章是作为服务治理的番外篇讲述，对注册中心的另一种实现方案探讨。也为接下来讲述SPI做好铺垫。
那么本章是基于redis作为存储中间件，实现服务治理，也就是图片中的第1，2，3步，思路跟zookeeper实现方式一致，存储结构也大致相同。使用redis的list类型。想详细了解redis的，请跳转至redis妙用，这里讲述了redis的各种应用场景，以及将遇到的坑。
项目结构介绍
本节涉及博客中代码的module，farpc-registry（服务治理），这章对IRegistrar进行了修改，将init()沉在AbstractRegistrar，在AbstractRegistrar的构造方法中调用init()，防止调用IRegistrar时，忘记调用init()，如下：
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| public interface IRegistrar {
void register(String providerAddress, String service);
String discover(String service);
}
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| public abstract class AbstractRegistrar implements IRegistrar {
protected static final String FOLDER = "/faregistrys";
protected static final String SEPARATOR = "/";
public AbstractRegistrar() {
String address = Property.Registry.address;
init(address);
}
public String discover(String service) {
List<String> providers = lookup(service);
ILoadbalance loadbalance = new RoundLoadBalanceImpl();
String select = loadbalance.select(providers);
return select;
}
protected abstract void init(String address);
protected abstract List<String> lookup(String service);
}
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redis实现注册中心
使用redis作为注册中心跟zookeeper的逻辑是一样的，所以这章不会像之前那样一步步推理了，直接铺代码了。我们先依赖maven，我们选择jedis操作redis。
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| <dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.5.0</version>
</dependency>
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然后这里新增了两个类，RedisOparetor、RedisRegistrarImpl，RedisOparetor用来初始化redis连接，RedisRegistrarImpl主要继承AbstractRegistrar来实现IRegistrar。
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| public class RedisOparetor {
private static Logger logger = LoggerFactory.getLogger(RedisOparetor.class);
private static int MAX_ACTIVE = 1024;
private static int MAX_IDLE = 200;
private static int MAX_WAIT = 10000;
private static int TIMEOUT = 10000;
private static boolean TEST_ON_BORROW = true;
private static JedisPool jedisPool = null;
public static void init(String addr) {
if (jedisPool == null) {
synchronized (RedisOparetor.class) {
if (jedisPool == null) {
try {
String[] split = addr.split(":");
String host = split[0];
Integer port = Integer.parseInt(split[1]);
JedisPoolConfig config = new JedisPoolConfig();
config.setMaxTotal(MAX_ACTIVE);
config.setMaxIdle(MAX_IDLE);
config.setMaxWaitMillis(MAX_WAIT);
config.setTestOnBorrow(TEST_ON_BORROW);
jedisPool = new JedisPool(config, host, port, TIMEOUT);
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
}
}
}
}
public synchronized static Jedis getJedis() {
try {
if (jedisPool != null) {
Jedis resource = jedisPool.getResource();
return resource;
} else {
throw new RuntimeException("call RedisOparetor.getJedis, connection is closed");
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
throw new RuntimeException(e);
}
}
public static void returnResource(final Jedis jedis) {
if (jedis != null) {
jedisPool.returnResource(jedis);
}
}
}
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| public class RedisRegistrarImpl extends AbstractRegistrar {
public void register(String providerAddress, String service) {
RedisOparetor.getJedis().lpush(FOLDER + SEPARATOR + service, providerAddress);
}
@Override
protected void init(String address) {
RedisOparetor.init(address);
}
@Override
public List<String> lookup(String service) {
List<String> lrange = RedisOparetor.getJedis().lrange(FOLDER + SEPARATOR + service, 0, -1);
return lrange;
}
}
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测试
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| @Test
public void redisTest() throws IOException {
IRegistrar registrar = new RedisRegistrarImpl();
registrar.register("127.0.0.1:20880", "com.ofcoder.farpc.demo.api.IWelcome");
System.in.read();
}
@Test
public void test() throws IOException {
IRegistrar registrar = new RedisRegistrarImpl();
System.out.println(registrar.discover("com.ofcoder.farpc.demo.api.IWelcome"));
}
------------------------------------
127.0.0.1:20880
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总结
其实我没啥好总结的，就是预测一下下一章，下一章讲述的是dubbo值得一吹的SPI。我们使用SPI整合redis、zookeeper。