[feat]add random loadbalance

example-client/src/main/java/github/javaguide/NettyClientMain.java

@@ -17,6 +17,8 @@ public class NettyClientMain {
         //如需使用 assert 断言，需要在 VM options 添加参数：-ea
         assert "Hello description is 222".equals(hello);
         Thread.sleep(12000);
-        helloService.hello(new Hello("111", "222"));
+        for (int i = 0; i < 10; i++) {
+            helloService.hello(new Hello("111", "222"));
+        }
     }
 }

example-server/src/main/java/github/javaguide/NettyServerMain2.java

+package github.javaguide;
+
+import github.javaguide.remoting.transport.netty.server.NettyServer;
+
+/**
+ * @author shuang.kou
+ * @createTime 2020年05月10日 07:25:00
+ */
+public class NettyServerMain2 {
+    public static void main(String[] args) {
+        HelloService helloService = new HelloServiceImpl();
+        NettyServer nettyServer = new NettyServer("127.0.0.1", 9998);
+        nettyServer.publishService(helloService, HelloService.class);
+    }
+}

rpc-framework-simple/src/main/java/github/javaguide/loadbalance/AbstractLoadBalance.java

+package github.javaguide.loadbalance;
+
+import java.util.List;
+
+/**
+ * @author shuang.kou
+ * @createTime 2020年06月21日 07:44:00
+ */
+public abstract class AbstractLoadBalance implements LoadBalance {
+    @Override
+    public String selectServiceAddress(List<String> serviceAddresses) {
+        if (serviceAddresses == null || serviceAddresses.size() == 0) {
+            return null;
+        }
+        if (serviceAddresses.size() == 1) {
+            return serviceAddresses.get(0);
+        }
+        return doSelect(serviceAddresses);
+    }
+
+    protected abstract String doSelect(List<String> serviceAddresses);
+
+}

rpc-framework-simple/src/main/java/github/javaguide/loadbalance/LoadBalance.java

+package github.javaguide.loadbalance;
+
+import java.util.List;
+
+/**
+ * @author shuang.kou
+ * @createTime 2020年06月21日 07:44:00
+ */
+public interface LoadBalance {
+    /**
+     * 在已有服务提供地址列表中选择一个
+     *
+     * @param serviceAddresses 服务地址列表
+     * @return 目标服务地址
+     */
+    String selectServiceAddress(List<String> serviceAddresses);
+}

rpc-framework-simple/src/main/java/github/javaguide/loadbalance/RandomLoadBalance.java

+package github.javaguide.loadbalance;
+
+import java.util.List;
+import java.util.Random;
+
+/**
+ * @author shuang.kou
+ * @createTime 2020年06月21日 07:47:00
+ */
+public class RandomLoadBalance extends AbstractLoadBalance {
+    @Override
+    protected String doSelect(List<String> serviceAddresses) {
+        Random random = new Random();
+        return serviceAddresses.get(random.nextInt(serviceAddresses.size()));
+    }
+}

rpc-framework-simple/src/main/java/github/javaguide/registry/ZkServiceDiscovery.java

 package github.javaguide.registry;
 
+import github.javaguide.loadbalance.LoadBalance;
+import github.javaguide.loadbalance.RandomLoadBalance;
 import github.javaguide.utils.zk.CuratorUtils;
 import lombok.extern.slf4j.Slf4j;
 
 import java.net.InetSocketAddress;
+import java.util.List;
 
 /**
  * 基于 zookeeper 实现服务发现
@@ -13,14 +16,20 @@ import java.net.InetSocketAddress;
  */
 @Slf4j
 public class ZkServiceDiscovery implements ServiceDiscovery {
+    private final LoadBalance loadBalance;
+
+    public ZkServiceDiscovery() {
+        this.loadBalance = new RandomLoadBalance();
+    }
 
     @Override
     public InetSocketAddress lookupService(String serviceName) {
-        // TODO(shuang.kou):feat: 负载均衡
         // 这里直接去了第一个找到的服务地址,eg:127.0.0.1:9999
-        String serviceAddress = CuratorUtils.getChildrenNodes(serviceName).get(0);
-        log.info("成功找到服务地址:[{}]", serviceAddress);
-        String[] socketAddressArray = serviceAddress.split(":");
+        List<String> serviceUrlList = CuratorUtils.getChildrenNodes(serviceName);
+        // 负载均衡
+        String targetServiceUrl = loadBalance.selectServiceAddress(serviceUrlList);
+        log.info("成功找到服务地址:[{}]", targetServiceUrl);
+        String[] socketAddressArray = targetServiceUrl.split(":");
         String host = socketAddressArray[0];
         int port = Integer.parseInt(socketAddressArray[1]);
         return new InetSocketAddress(host, port);