diff --git a/core/src/main/java/com/usthe/sureness/provider/ducument/DocumentResourceAccess.java b/core/src/main/java/com/usthe/sureness/provider/ducument/DocumentResourceAccess.java
index 830d1ee0a305c43ac6c828f1e36acbf43b84783f..b3ff72227f66bca40fde8d8f6ba6b0d18cd768ef 100644
--- a/core/src/main/java/com/usthe/sureness/provider/ducument/DocumentResourceAccess.java
+++ b/core/src/main/java/com/usthe/sureness/provider/ducument/DocumentResourceAccess.java
@@ -41,25 +41,32 @@ public class DocumentResourceAccess {
      */
     public static DocumentResourceEntity loadConfig(String yamlFileName) throws IOException {
         Yaml yaml = new Yaml();
-        InputStream inputStream = DocumentResourceAccess.class.getClassLoader().getResourceAsStream(yamlFileName);
-        if (inputStream == null) {
-            inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(yamlFileName);
-        }
-        if (inputStream == null) {
-            File yamlFile = new File(yamlFileName);
-            if (yamlFile.exists()) {
-                try (FileInputStream fileInputStream = new FileInputStream(yamlFile)) {
-                    return yaml.loadAs(fileInputStream, DocumentResourceEntity.class);
-                } catch (IOException e) {
-                    throw new IOException(e);
+        InputStream inputStream = null;
+        try {
+            inputStream = DocumentResourceAccess.class.getClassLoader().getResourceAsStream(yamlFileName);
+            if (inputStream == null) {
+                inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(yamlFileName);
+            }
+            if (inputStream == null) {
+                File yamlFile = new File(yamlFileName);
+                if (yamlFile.exists()) {
+                    try (FileInputStream fileInputStream = new FileInputStream(yamlFile)) {
+                        return yaml.loadAs(fileInputStream, DocumentResourceEntity.class);
+                    } catch (IOException e) {
+                        throw new IOException(e);
+                    }
                 }
             }
+            if (inputStream == null) {
+                throw new FileNotFoundException("sureness file: " + DEFAULT_FILE_NAME + " not found, " +
+                        "please create the file if you need config resource");
+            }
+            return yaml.loadAs(inputStream, DocumentResourceEntity.class);
+        } finally {
+            if (inputStream != null) {
+                inputStream.close();
+            }
         }
-        if (inputStream == null) {
-            throw new FileNotFoundException("sureness file: " + DEFAULT_FILE_NAME + " not found, " +
-                    "please create the file if you need config resource");
-        }
-        return yaml.loadAs(inputStream, DocumentResourceEntity.class);
     }
 
     /**
diff --git a/core/src/main/java/com/usthe/sureness/util/ClassScanner.java b/core/src/main/java/com/usthe/sureness/util/ClassScanner.java
index 22ed1521d94dd8ea667894757d21830f49f0af33..5ae939776b7b941c3af4e969bf42c5fe4cf6fd5b 100644
--- a/core/src/main/java/com/usthe/sureness/util/ClassScanner.java
+++ b/core/src/main/java/com/usthe/sureness/util/ClassScanner.java
@@ -240,30 +240,30 @@ public enum ClassScanner {
     private static List<Class<?>> recursiveScan4Jar(String pkg, String jarPath) throws IOException {
         List<Class<?>> classList = new LinkedList<>();
 
-        JarInputStream jin = new JarInputStream(new FileInputStream(jarPath));
-        JarEntry entry = jin.getNextJarEntry();
-        while (entry != null) {
-            String name = entry.getName();
-            entry = jin.getNextJarEntry();
-
-            if (!name.contains(package2Path(pkg))) {
-                continue;
-            }
-            if (isClass(name)) {
-                if (isAnonymousInnerClass(name)) {
+        try (JarInputStream jin = new JarInputStream(new FileInputStream(jarPath))) {
+            JarEntry entry = jin.getNextJarEntry();
+            while (entry != null) {
+                String name = entry.getName();
+                entry = jin.getNextJarEntry();
+
+                if (!name.contains(package2Path(pkg))) {
                     continue;
                 }
-
-                String className = classFile2SimpleClass(path2Package(name));
-                try {
-                    Class<?> clz = Thread.currentThread().getContextClassLoader().loadClass(className);
-                    classList.add(clz);
-                } catch (ClassNotFoundException | LinkageError e) {
-                    log.error("Warning: Can not load class: {}", className);
+                if (isClass(name)) {
+                    if (isAnonymousInnerClass(name)) {
+                        continue;
+                    }
+
+                    String className = classFile2SimpleClass(path2Package(name));
+                    try {
+                        Class<?> clz = Thread.currentThread().getContextClassLoader().loadClass(className);
+                        classList.add(clz);
+                    } catch (ClassNotFoundException | LinkageError e) {
+                        log.error("Warning: Can not load class: {}", className);
+                    }
                 }
             }
         }
-
         return classList;
     }
 
diff --git a/core/src/main/java/com/usthe/sureness/util/SurenessCommonUtil.java b/core/src/main/java/com/usthe/sureness/util/SurenessCommonUtil.java
index f4b578c9475fd35fd2d563f281b2c2f4a5bb1474..deac7af7bfddcd675faecea1901722fef3ef12a0 100644
--- a/core/src/main/java/com/usthe/sureness/util/SurenessCommonUtil.java
+++ b/core/src/main/java/com/usthe/sureness/util/SurenessCommonUtil.java
@@ -21,6 +21,7 @@ public class SurenessCommonUtil {
     private static final String PATH_SPLIT = "/";
 
     private static final String RANDOM_CHAR = "abcdefghijklmnopqrstuvwxyz0123456789";
+    private static final Random RANDOM = new Random();
 
     /**
      * match the userAgent
@@ -58,10 +59,9 @@ public class SurenessCommonUtil {
         if (length < 1) {
             length = 6;
         }
-        Random random = new Random();
         StringBuilder sb = new StringBuilder();
         for (int i = 0; i < length; i++) {
-            int number = random.nextInt(RANDOM_CHAR.length());
+            int number = RANDOM.nextInt(RANDOM_CHAR.length());
             sb.append(RANDOM_CHAR.charAt(number));
         }
         return sb.toString();