Dubbo源码学习--redis协议（六）
基于 Redis 1 实现的 RPC 协议 2。
注册 redis 服务的地址
RegistryFactory registryFactory = ExtensionLoader.getExtensionLoader(RegistryFactory.class).getAdaptiveExtension();
Registry registry = registryFactory.getRegistry(URL.valueOf("zookeeper://10.20.153.10:2181"));
registry.register(URL.valueOf("redis://10.20.153.11/com.foo.BarService?category=providers&dynamic=false&application=foo&group=member&loadbalance=consistenthash"));
在客户端引用
在客户端使用 3：
<dubbo:reference id="store" interface="java.util.Map" group="member" />
或者，点对点直连：
<dubbo:reference id="store" interface="java.util.Map" url="redis://10.20.153.10:6379" />
也可以使用自定义接口：
<dubbo:reference id="store" interface="com.foo.StoreService" url="redis://10.20.153.10:6379" />
方法名建议和 redis 的标准方法名相同，即：get(key), set(key, value), delet(key)。
如果方法名和 redis 的标准方法名不相同，则需要配置映射关系 4：
<dubbo:reference id="cache" interface="com.foo.CacheService" url="memcached://10.20.153.10:11211" p:set="putFoo" p:get="getFoo" p:delete="removeFoo" />
1. Redis 是一个高效的 KV 存储服务器 ↩
2.
2.3.0 以上版本支持 ↩
3. 不需要感知 Redis 的地址 ↩
4. 其中 "p:xxx" 为 spring 的标准 p 标签 ↩
在RedisProtocol中同样提供了export和refer两个方法
（1）export方法：目前redis协议不支持对外提供服务的操作
（2）refer方法：在refer方法中redisProtocol完成了数据的设置、查询和删除操作，这样是否几个服务消费者就可以共享数据。
redis协议中没有服务提供者，简单来说更像是消费者将增删数据放到redis中，这样消费者自己及其他消费者可以通过接口进行获取数据，并设置数据的超时时间。
public class RedisProtocol extends AbstractProtocol {
public static final int DEFAULT_PORT = 6379;
public int getDefaultPort() {
return DEFAULT_PORT;
}
//redis协议无法暴露服务
public Exporter export(final Invoker invoker) throws RpcException {
throw new UnsupportedOperationException("Unsupported export redis service. url: " + invoker.getUrl());
}
private Serialization getSerialization(URL url) {
return ExtensionLoader.getExtensionLoader(Serialization.class).getExtension(url.getParameter(Constants.SERIALIZATION_KEY, "java"));
}
//redis根据方法名称，完成向redis中添加数据、获取数据和删除数据操作
public Invoker refer(final Class type, final URL url) throws RpcException {
try {
GenericObjectPoolConfig config = new GenericObjectPoolConfig();
config.setTestOnBorrow(url.getParameter("test.on.borrow", true));
config.setTestOnReturn(url.getParameter("test.on.return", false));
config.setTestWhileIdle(url.getParameter("test.while.idle", false));
if (url.getParameter("max.idle", 0) > 0)
config.setMaxIdle(url.getParameter("max.idle", 0));
if (url.getParameter("min.idle", 0) > 0)
config.setMinIdle(url.getParameter("min.idle", 0));
if (url.getParameter("max.active", 0) > 0)
config.setMaxTotal(url.getParameter("max.active", 0));
if (url.getParameter("max.total", 0) > 0)
config.setMaxTotal(url.getParameter("max.total", 0));
if (url.getParameter("max.wait", 0) > 0)
config.setMaxWaitMillis(url.getParameter("max.wait", 0));
if (url.getParameter("num.tests.per.eviction.run", 0) > 0)
config.setNumTestsPerEvictionRun(url.getParameter("num.tests.per.eviction.run", 0));
if (url.getParameter("time.between.eviction.runs.millis", 0) > 0)
config.setTimeBetweenEvictionRunsMillis(url.getParameter("time.between.eviction.runs.millis", 0));
if (url.getParameter("min.evictable.idle.time.millis", 0) > 0)
config.setMinEvictableIdleTimeMillis(url.getParameter("min.evictable.idle.time.millis", 0));
final JedisPool jedisPool = new JedisPool(config, url.getHost(), url.getPort(DEFAULT_PORT),
url.getParameter(Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT));
final int expiry = url.getParameter("expiry", 0);
final String get = url.getParameter("get", "get");
final String set = url.getParameter("set", Map.class.equals(type) ? "put" : "set");
final String delete = url.getParameter("delete", Map.class.equals(type) ? "remove" : "delete");
//创建代理实现类
return new AbstractInvoker(type, url) {
protected Result doInvoke(Invocation invocation) throws Throwable {
Jedis resource = null;
try {
resource = jedisPool.getResource();
//如果是get方法则从redis中获取数据
if (get.equals(invocation.getMethodName())) {
if (invocation.getArguments().length != 1) {
throw new IllegalArgumentException("The redis get method arguments mismatch, must only one arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
}
byte[] value = resource.get(String.valueOf(invocation.getArguments()[0]).getBytes());
if (value == null) {
return new RpcResult();
}
ObjectInput oin = getSerialization(url).deserialize(url, new ByteArrayInputStream(value));
return new RpcResult(oin.readObject());
//如果是set方法则向redis中添加数据
} else if (set.equals(invocation.getMethodName())) {
if (invocation.getArguments().length != 2) {
throw new IllegalArgumentException("The redis set method arguments mismatch, must be two arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
}
byte[] key = String.valueOf(invocation.getArguments()[0]).getBytes();
ByteArrayOutputStream output = new ByteArrayOutputStream();
ObjectOutput value = getSerialization(url).serialize(url, output);
value.writeObject(invocation.getArguments()[1]);
resource.set(key, output.toByteArray());
if (expiry > 1000) {
resource.expire(key, expiry / 1000);
}
return new RpcResult();
//如果是delete方法则删除redis中相关数据
} else if (delete.equals(invocation.getMethodName())) {
if (invocation.getArguments().length != 1) {
throw new IllegalArgumentException("The redis delete method arguments mismatch, must only one arguments. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url);
}
resource.del(String.valueOf(invocation.getArguments()[0]).getBytes());
return new RpcResult();
} else {
throw new UnsupportedOperationException("Unsupported method " + invocation.getMethodName() + " in redis service.");
}
} catch (Throwable t) {
RpcException re = new RpcException("Failed to invoke redis service method. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url + ", cause: " + t.getMessage(), t);
if (t instanceof TimeoutException || t instanceof SocketTimeoutException) {
re.setCode(RpcException.TIMEOUT_EXCEPTION);
} else if (t instanceof JedisConnectionException || t instanceof IOException) {
re.setCode(RpcException.NETWORK_EXCEPTION);
} else if (t instanceof JedisDataException) {
re.setCode(RpcException.SERIALIZATION_EXCEPTION);
}
throw re;
} finally {
if (resource != null) {
try {
jedisPool.returnResource(resource);
} catch (Throwable t) {
logger.warn("returnResource error: " + t.getMessage(), t);
}
}
}
}
public void destroy() {
super.destroy();
try {
jedisPool.destroy();
} catch (Throwable e) {
logger.warn(e.getMessage(), e);
}
}
};
} catch (Throwable t) {
throw new RpcException("Failed to refer redis service. interface: " + type.getName() + ", url: " + url + ", cause: " + t.getMessage(), t);
}
}
}