diff --git a/rpc-framework-common/src/main/java/github/javaguide/extension/ExtensionLoader.java b/rpc-framework-common/src/main/java/github/javaguide/extension/ExtensionLoader.java
index fc9e116df44128ab316c7ac8c7efea70adcb4fb1..be16e9059a6d8975efef94d293e747717bf0a438 100644
--- a/rpc-framework-common/src/main/java/github/javaguide/extension/ExtensionLoader.java
+++ b/rpc-framework-common/src/main/java/github/javaguide/extension/ExtensionLoader.java
@@ -1,5 +1,6 @@
 package github.javaguide.extension;
 
+import github.javaguide.utils.StringUtil;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.BufferedReader;
@@ -51,7 +52,7 @@ public final class ExtensionLoader<T> {
     }
 
     public T getExtension(String name) {
-        if (name == null || name.isEmpty()) {
+        if (StringUtil.isBlank(name)) {
             throw new IllegalArgumentException("Extension name should not be null or empty.");
         }
         // firstly get from cache, if not hit, create one
diff --git a/rpc-framework-common/src/main/java/github/javaguide/utils/CollectionUtil.java b/rpc-framework-common/src/main/java/github/javaguide/utils/CollectionUtil.java
new file mode 100644
index 0000000000000000000000000000000000000000..dc3198197706bcfd8931b917cbd1f83368e30ab1
--- /dev/null
+++ b/rpc-framework-common/src/main/java/github/javaguide/utils/CollectionUtil.java
@@ -0,0 +1,17 @@
+package github.javaguide.utils;
+
+import java.util.Collection;
+
+/**
+ * 集合工具类
+ *
+ * @author zhanghua
+ * @createTime 2022/3/6 12:58 上午
+ */
+public class CollectionUtil {
+
+    public static boolean isEmpty(Collection<?> c) {
+        return c == null || c.isEmpty();
+    }
+
+}
diff --git a/rpc-framework-common/src/main/java/github/javaguide/utils/StringUtil.java b/rpc-framework-common/src/main/java/github/javaguide/utils/StringUtil.java
new file mode 100644
index 0000000000000000000000000000000000000000..97a3afd87c66f79ec4d10e18b131eb9ba64ee890
--- /dev/null
+++ b/rpc-framework-common/src/main/java/github/javaguide/utils/StringUtil.java
@@ -0,0 +1,22 @@
+package github.javaguide.utils;
+
+/**
+ * String 工具类
+ *
+ * @author zhanghua
+ * @createTime 2022/3/6 12:58 上午
+ */
+public class StringUtil {
+
+    public static boolean isBlank(String s) {
+        if (s == null || s.length() == 0) {
+            return true;
+        }
+        for (int i = 0; i < s.length(); ++i) {
+            if (!Character.isWhitespace(s.charAt(i))) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
diff --git a/rpc-framework-common/src/main/java/github/javaguide/utils/concurrent/threadpool/ThreadPoolFactoryUtils.java b/rpc-framework-common/src/main/java/github/javaguide/utils/concurrent/threadpool/ThreadPoolFactoryUtil.java
similarity index 98%
rename from rpc-framework-common/src/main/java/github/javaguide/utils/concurrent/threadpool/ThreadPoolFactoryUtils.java
rename to rpc-framework-common/src/main/java/github/javaguide/utils/concurrent/threadpool/ThreadPoolFactoryUtil.java
index 2708f39374bd762fa458b20c2255b6c48a5b973b..016a61a38ff5e779791253c2b0d2d0d5c3c0182b 100644
--- a/rpc-framework-common/src/main/java/github/javaguide/utils/concurrent/threadpool/ThreadPoolFactoryUtils.java
+++ b/rpc-framework-common/src/main/java/github/javaguide/utils/concurrent/threadpool/ThreadPoolFactoryUtil.java
@@ -20,7 +20,7 @@ import java.util.concurrent.TimeUnit;
  * @createTime 2020年05月26日 16:00:00
  */
 @Slf4j
-public final class ThreadPoolFactoryUtils {
+public final class ThreadPoolFactoryUtil {
 
     /**
      * 通过 threadNamePrefix 来区分不同线程池（我们可以把相同 threadNamePrefix 的线程池看作是为同一业务场景服务）。
@@ -29,7 +29,7 @@ public final class ThreadPoolFactoryUtils {
      */
     private static final Map<String, ExecutorService> THREAD_POOLS = new ConcurrentHashMap<>();
 
-    private ThreadPoolFactoryUtils() {
+    private ThreadPoolFactoryUtil() {
 
     }
 
diff --git a/rpc-framework-simple/src/main/java/github/javaguide/config/CustomShutdownHook.java b/rpc-framework-simple/src/main/java/github/javaguide/config/CustomShutdownHook.java
index b126c7233b67a28d84b28d6c7e26f6ce88661bf1..eea8be1b335500eb0ec97c2e1af445adbdbd394a 100644
--- a/rpc-framework-simple/src/main/java/github/javaguide/config/CustomShutdownHook.java
+++ b/rpc-framework-simple/src/main/java/github/javaguide/config/CustomShutdownHook.java
@@ -2,7 +2,7 @@ package github.javaguide.config;
 
 import github.javaguide.registry.zk.util.CuratorUtils;
 import github.javaguide.remoting.transport.netty.server.NettyRpcServer;
-import github.javaguide.utils.concurrent.threadpool.ThreadPoolFactoryUtils;
+import github.javaguide.utils.concurrent.threadpool.ThreadPoolFactoryUtil;
 import lombok.extern.slf4j.Slf4j;
 
 import java.net.InetAddress;
@@ -31,7 +31,7 @@ public class CustomShutdownHook {
                 CuratorUtils.clearRegistry(CuratorUtils.getZkClient(), inetSocketAddress);
             } catch (UnknownHostException ignored) {
             }
-            ThreadPoolFactoryUtils.shutDownAllThreadPool();
+            ThreadPoolFactoryUtil.shutDownAllThreadPool();
         }));
     }
 }
diff --git a/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/AbstractLoadBalance.java b/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/AbstractLoadBalance.java
index 29e805d2c2e9b154e8360ff321bac3e290dc083d..9febf6cc45802ee9698e029ef4413f26d9664535 100644
--- a/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/AbstractLoadBalance.java
+++ b/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/AbstractLoadBalance.java
@@ -1,6 +1,7 @@
 package github.javaguide.loadbalance;
 
 import github.javaguide.remoting.dto.RpcRequest;
+import github.javaguide.utils.CollectionUtil;
 
 import java.util.List;
 
@@ -13,7 +14,7 @@ import java.util.List;
 public abstract class AbstractLoadBalance implements LoadBalance {
     @Override
     public String selectServiceAddress(List<String> serviceAddresses, RpcRequest rpcRequest) {
-        if (serviceAddresses == null || serviceAddresses.size() == 0) {
+        if (CollectionUtil.isEmpty(serviceAddresses)) {
             return null;
         }
         if (serviceAddresses.size() == 1) {
diff --git a/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/LoadBalance.java b/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/LoadBalance.java
index 4a6fa26675e2a1d6c39e0631ae38a2efbd5aebd7..0ae6ad82cd2facbb9276be0a3d2aacdb51144927 100644
--- a/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/LoadBalance.java
+++ b/rpc-framework-simple/src/main/java/github/javaguide/loadbalance/LoadBalance.java
@@ -16,8 +16,9 @@ public interface LoadBalance {
     /**
      * Choose one from the list of existing service addresses list
      *
-     * @param serviceAddresses Service address list
+     * @param serviceUrlList Service address list
+     * @param rpcRequest
      * @return target service address
      */
-    String selectServiceAddress(List<String> serviceAddresses, RpcRequest rpcRequest);
+    String selectServiceAddress(List<String> serviceUrlList, RpcRequest rpcRequest);
 }
diff --git a/rpc-framework-simple/src/main/java/github/javaguide/registry/zk/ZkServiceDiscoveryImpl.java b/rpc-framework-simple/src/main/java/github/javaguide/registry/zk/ZkServiceDiscoveryImpl.java
index 0a13a4897b07289eb5bd72fe4ba9f64eae268455..73d603a10c055cfc93d15d4be196ee7b7130545b 100644
--- a/rpc-framework-simple/src/main/java/github/javaguide/registry/zk/ZkServiceDiscoveryImpl.java
+++ b/rpc-framework-simple/src/main/java/github/javaguide/registry/zk/ZkServiceDiscoveryImpl.java
@@ -7,6 +7,7 @@ import github.javaguide.loadbalance.LoadBalance;
 import github.javaguide.registry.ServiceDiscovery;
 import github.javaguide.registry.zk.util.CuratorUtils;
 import github.javaguide.remoting.dto.RpcRequest;
+import github.javaguide.utils.CollectionUtil;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.curator.framework.CuratorFramework;
 
@@ -32,7 +33,7 @@ public class ZkServiceDiscoveryImpl implements ServiceDiscovery {
         String rpcServiceName = rpcRequest.getRpcServiceName();
         CuratorFramework zkClient = CuratorUtils.getZkClient();
         List<String> serviceUrlList = CuratorUtils.getChildrenNodes(zkClient, rpcServiceName);
-        if (serviceUrlList == null || serviceUrlList.size() == 0) {
+        if (CollectionUtil.isEmpty(serviceUrlList)) {
             throw new RpcException(RpcErrorMessageEnum.SERVICE_CAN_NOT_BE_FOUND, rpcServiceName);
         }
         // load balancing
diff --git a/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/netty/server/NettyRpcServer.java b/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/netty/server/NettyRpcServer.java
index bc90523bdad757a07e387067e49bd0bb3518b20a..428737058bc4c6358285b87422dd7634552fe804 100644
--- a/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/netty/server/NettyRpcServer.java
+++ b/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/netty/server/NettyRpcServer.java
@@ -8,7 +8,7 @@ import github.javaguide.provider.impl.ZkServiceProviderImpl;
 import github.javaguide.remoting.transport.netty.codec.RpcMessageDecoder;
 import github.javaguide.remoting.transport.netty.codec.RpcMessageEncoder;
 import github.javaguide.utils.RuntimeUtil;
-import github.javaguide.utils.concurrent.threadpool.ThreadPoolFactoryUtils;
+import github.javaguide.utils.concurrent.threadpool.ThreadPoolFactoryUtil;
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelInitializer;
@@ -56,7 +56,7 @@ public class NettyRpcServer {
         EventLoopGroup workerGroup = new NioEventLoopGroup();
         DefaultEventExecutorGroup serviceHandlerGroup = new DefaultEventExecutorGroup(
                 RuntimeUtil.cpus() * 2,
-                ThreadPoolFactoryUtils.createThreadFactory("service-handler-group", false)
+                ThreadPoolFactoryUtil.createThreadFactory("service-handler-group", false)
         );
         try {
             ServerBootstrap b = new ServerBootstrap();
diff --git a/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/socket/SocketRpcServer.java b/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/socket/SocketRpcServer.java
index 1426569eb11e1da1e656d5fb0f7abba884d56c0c..d2e29e4e6a11c140848b40d6ea69b2e3e9477b43 100644
--- a/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/socket/SocketRpcServer.java
+++ b/rpc-framework-simple/src/main/java/github/javaguide/remoting/transport/socket/SocketRpcServer.java
@@ -5,7 +5,7 @@ import github.javaguide.config.RpcServiceConfig;
 import github.javaguide.factory.SingletonFactory;
 import github.javaguide.provider.ServiceProvider;
 import github.javaguide.provider.impl.ZkServiceProviderImpl;
-import github.javaguide.utils.concurrent.threadpool.ThreadPoolFactoryUtils;
+import github.javaguide.utils.concurrent.threadpool.ThreadPoolFactoryUtil;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
@@ -29,7 +29,7 @@ public class SocketRpcServer {
 
 
     public SocketRpcServer() {
-        threadPool = ThreadPoolFactoryUtils.createCustomThreadPoolIfAbsent("socket-server-rpc-pool");
+        threadPool = ThreadPoolFactoryUtil.createCustomThreadPoolIfAbsent("socket-server-rpc-pool");
         serviceProvider = SingletonFactory.getInstance(ZkServiceProviderImpl.class);
     }