diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricSearcher.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricSearcher.java
index e1e857632e..3ddf94db74 100755
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricSearcher.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricSearcher.java
@@ -36,8 +36,8 @@ public class MetricSearcher {
     private static final Charset defaultCharset = Charset.forName(SentinelConfig.charset());
     private final MetricsReader metricsReader;
 
-    private String baseDir;
-    private String baseFileName;
+    private final String baseDir;
+    private final String baseFileName;
 
     private Position lastPosition = new Position();
 
@@ -64,10 +64,11 @@ public MetricSearcher(String baseDir, String baseFileName, Charset charset) {
         if (charset == null) {
             throw new IllegalArgumentException("charset can't be null");
         }
-        this.baseDir = baseDir;
+        String baseDirContainer = baseDir;
         if (!baseDir.endsWith(File.separator)) {
-            this.baseDir += File.separator;
+            baseDirContainer += File.separator;
         }
+        this.baseDir = baseDirContainer;
         this.baseFileName = baseFileName;
         metricsReader = new MetricsReader(charset);
     }
@@ -117,6 +118,7 @@ public synchronized List<MetricNode> findByTimeAndResource(long beginTimeMs, lon
         //    + "], " + identity + ")");
         int i = 0;
         long offsetInIndex = 0;
+        //noinspection StatementWithEmptyBody
         if (validPosition(beginTimeMs)) {
             i = fileNames.indexOf(lastPosition.metricFileName);
             if (i == -1) {
@@ -171,22 +173,13 @@ private boolean validPosition(long beginTimeMs) {
         if (!new File(lastPosition.indexFileName).exists()) {
             return false;
         }
-        FileInputStream in = null;
-        try {
-            in = new FileInputStream(lastPosition.indexFileName);
+        try (FileInputStream in = new FileInputStream(lastPosition.indexFileName)) {
             in.getChannel().position(lastPosition.offsetInIndex);
             DataInputStream indexIn = new DataInputStream(in);
             // timestamp(second) in the specific position == that we cached
             return indexIn.readLong() == lastPosition.second;
         } catch (Exception e) {
             return false;
-        } finally {
-            if (in != null) {
-                try {
-                    in.close();
-                } catch (Exception ignore) {
-                }
-            }
         }
     }
 
@@ -200,13 +193,12 @@ private long findOffset(long beginTime, String metricFileName,
         long beginSecond = beginTime / 1000;
         FileInputStream in = new FileInputStream(idxFileName);
         in.getChannel().position(offsetInIndex);
-        DataInputStream indexIn = new DataInputStream(in);
-        long offset;
-        try {
+        try (DataInputStream indexIn = new DataInputStream(in)) {
+            long offset;
             long second;
             lastPosition.offsetInIndex = in.getChannel().position();
             while ((second = indexIn.readLong()) < beginSecond) {
-                offset = indexIn.readLong();
+                indexIn.readLong();
                 lastPosition.offsetInIndex = in.getChannel().position();
             }
             offset = indexIn.readLong();
@@ -216,8 +208,6 @@ private long findOffset(long beginTime, String metricFileName,
             return offset;
         } catch (EOFException ignore) {
             return -1;
-        } finally {
-            indexIn.close();
         }
     }
 }
diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricsReader.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricsReader.java
index b705b34a2e..7303b1f307 100644
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricsReader.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricsReader.java
@@ -39,15 +39,13 @@ public MetricsReader(Charset charset) {
     }
 
     /**
-     * @return if should continue read, return true, else false.
+     * @return if it should continue read, return true, else false.
      */
     boolean readMetricsInOneFileByEndTime(List<MetricNode> list, String fileName, long offset,
                                           long beginTimeMs, long endTimeMs, String identity) throws Exception {
-        FileInputStream in = null;
         long beginSecond = beginTimeMs / 1000;
         long endSecond = endTimeMs / 1000;
-        try {
-            in = new FileInputStream(fileName);
+        try (FileInputStream in = new FileInputStream(fileName)) {
             in.getChannel().position(offset);
             BufferedReader reader = new BufferedReader(new InputStreamReader(in, charset));
             String line;
@@ -72,10 +70,6 @@ boolean readMetricsInOneFileByEndTime(List<MetricNode> list, String fileName, lo
                     return false;
                 }
             }
-        } finally {
-            if (in != null) {
-                in.close();
-            }
         }
         return true;
     }
@@ -89,9 +83,7 @@ void readMetricsInOneFile(List<MetricNode> list, String fileName,
         if (list.size() > 0) {
             lastSecond = list.get(list.size() - 1).getTimestamp() / 1000;
         }
-        FileInputStream in = null;
-        try {
-            in = new FileInputStream(fileName);
+        try (FileInputStream in = new FileInputStream(fileName)) {
             in.getChannel().position(offset);
             BufferedReader reader = new BufferedReader(new InputStreamReader(in, charset));
             String line;
@@ -108,10 +100,6 @@ void readMetricsInOneFile(List<MetricNode> list, String fileName,
                 }
                 lastSecond = currentSecond;
             }
-        } finally {
-            if (in != null) {
-                in.close();
-            }
         }
     }
 
@@ -121,7 +109,7 @@ void readMetricsInOneFile(List<MetricNode> list, String fileName,
      */
     List<MetricNode> readMetricsByEndTime(List<String> fileNames, int pos, long offset,
                                           long beginTimeMs, long endTimeMs, String identity) throws Exception {
-        List<MetricNode> list = new ArrayList<MetricNode>(1024);
+        List<MetricNode> list = new ArrayList<>(1024);
         if (readMetricsInOneFileByEndTime(list, fileNames.get(pos++), offset, beginTimeMs, endTimeMs, identity)) {
             while (pos < fileNames.size()
                 && readMetricsInOneFileByEndTime(list, fileNames.get(pos++), 0, beginTimeMs, endTimeMs, identity)) {
@@ -132,7 +120,7 @@ && readMetricsInOneFileByEndTime(list, fileNames.get(pos++), 0, beginTimeMs, end
 
     List<MetricNode> readMetrics(List<String> fileNames, int pos,
                                  long offset, int recommendLines) throws Exception {
-        List<MetricNode> list = new ArrayList<MetricNode>(recommendLines);
+        List<MetricNode> list = new ArrayList<>(recommendLines);
         readMetricsInOneFile(list, fileNames.get(pos++), offset, recommendLines);
         while (list.size() < recommendLines && pos < fileNames.size()) {
             readMetricsInOneFile(list, fileNames.get(pos++), 0, recommendLines);
diff --git a/sentinel-demo/sentinel-demo-zookeeper-datasource/src/main/java/com/alibaba/csp/sentinel/demo/datasource/zookeeper/ZookeeperConfigSender.java b/sentinel-demo/sentinel-demo-zookeeper-datasource/src/main/java/com/alibaba/csp/sentinel/demo/datasource/zookeeper/ZookeeperConfigSender.java
index 4b1e422340..7d977da312 100644
--- a/sentinel-demo/sentinel-demo-zookeeper-datasource/src/main/java/com/alibaba/csp/sentinel/demo/datasource/zookeeper/ZookeeperConfigSender.java
+++ b/sentinel-demo/sentinel-demo-zookeeper-datasource/src/main/java/com/alibaba/csp/sentinel/demo/datasource/zookeeper/ZookeeperConfigSender.java
@@ -6,6 +6,8 @@
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.data.Stat;
 
+import static org.apache.curator.framework.CuratorFrameworkFactory.newClient;
+
 /**
  * Zookeeper config sender for demo
  *
@@ -31,22 +33,21 @@ public static void main(String[] args) throws Exception {
                 + "  }\n"
                 + "]";
 
-        CuratorFramework zkClient = CuratorFrameworkFactory.newClient(remoteAddress, new ExponentialBackoffRetry(SLEEP_TIME, RETRY_TIMES));
-        zkClient.start();
-        String path = getPath(groupId, dataId);
-        Stat stat = zkClient.checkExists().forPath(path);
-        if (stat == null) {
-            zkClient.create().creatingParentContainersIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path, null);
-        }
-        zkClient.setData().forPath(path, rule.getBytes());
+        try(CuratorFramework zkClient = newClient(remoteAddress, new ExponentialBackoffRetry(SLEEP_TIME, RETRY_TIMES))) {
+            zkClient.start();
+            String path = getPath(groupId, dataId);
+            Stat stat = zkClient.checkExists().forPath(path);
+            if (stat == null) {
+                zkClient.create().creatingParentContainersIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path, null);
+            }
+            zkClient.setData().forPath(path, rule.getBytes());
 
-        try {
-            Thread.sleep(3000);
-        } catch (InterruptedException e) {
-            e.printStackTrace();
+            try {
+                Thread.sleep(3000);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
         }
-
-        zkClient.close();
     }
 
     private static String getPath(String groupId, String dataId) {