diff --git a/pom.xml b/pom.xml
index 2b3b1b7..66f96a1 100644
--- a/pom.xml
+++ b/pom.xml
@@ -69,12 +69,24 @@
             <groupId>com.zaxxer</groupId>
             <artifactId>HikariCP</artifactId>
             <version>4.0.3</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.slf4j</groupId>
+                    <artifactId>slf4j-api</artifactId>
+                </exclusion>
+            </exclusions>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.postgresql</groupId>
             <artifactId>postgresql</artifactId>
             <version>42.3.8</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.checkerframework</groupId>
+                    <artifactId>checker-qual</artifactId>
+                </exclusion>
+            </exclusions>
             <scope>test</scope>
         </dependency>
 
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/collection/MapWrapper.java b/src/main/java/xyz/zhouxy/plusone/commons/collection/MapWrapper.java
index 6330673..aa99322 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/collection/MapWrapper.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/collection/MapWrapper.java
@@ -49,7 +49,7 @@ public final class MapWrapper<K, V> extends AbstractMapWrapper<K, V, MapWrapper<
         return new Builder<>(new HashMap<>(initialCapacity, loadFactor));
     }
 
-    public static <K, V> Builder<K, V> wrapTreeMap() {
+    public static <K extends Comparable<? super K>, V> Builder<K, V> wrapTreeMap() {
         return new Builder<>(new TreeMap<>());
     }
 
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/function/Predicates.java b/src/main/java/xyz/zhouxy/plusone/commons/function/Predicates.java
index e1620f4..adb4989 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/function/Predicates.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/function/Predicates.java
@@ -42,9 +42,9 @@ public class Predicates {
      *         .and(StringUtils::isNotEmpty);
      * </pre>
      * 
-     * @param <T>
-     * @param predicate
-     * @return
+     * @param <T>       目标类型
+     * @param predicate 原 {@link Predicate} 实例
+     * @return 包装的 {@link Predicate} 实例
      */
     public static <T> Predicate<T> of(Predicate<? super T> predicate) {
         return predicate::test;
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/jdbc/DbRecord.java b/src/main/java/xyz/zhouxy/plusone/commons/jdbc/DbRecord.java
index e8c1892..472c00d 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/jdbc/DbRecord.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/jdbc/DbRecord.java
@@ -59,7 +59,7 @@ public class DbRecord extends AbstractMapWrapper<String, Object, DbRecord> {
     public <T> Set<T> getValueAsSet(String key) {
         return this.<Collection<T>>getAndConvert(key)
                 .map(l -> (l instanceof Set) ? (Set<T>) l : new HashSet<>(l))
-                .orElse(Collections.<T>emptySet());
+                .orElse(Collections.emptySet());
     }
 
     public OptionalInt getValueAsInt(String key) {
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/jdbc/ResultMap.java b/src/main/java/xyz/zhouxy/plusone/commons/jdbc/ResultMap.java
index de89740..1f078c8 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/jdbc/ResultMap.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/jdbc/ResultMap.java
@@ -24,5 +24,5 @@ import com.google.common.annotations.Beta;
 @Beta
 @FunctionalInterface
 public interface ResultMap<T> {
-    T map(ResultSet rs) throws SQLException;
+    T map(ResultSet rs, int rowNumber) throws SQLException;
 }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/jdbc/SimpleJdbcTemplate.java b/src/main/java/xyz/zhouxy/plusone/commons/jdbc/SimpleJdbcTemplate.java
index e0bab36..0600529 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/jdbc/SimpleJdbcTemplate.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/jdbc/SimpleJdbcTemplate.java
@@ -100,8 +100,9 @@ public class SimpleJdbcTemplate {
                 }
                 try (ResultSet rs = stmt.executeQuery()) {
                     List<T> result = new ArrayList<>();
+                    int rowNumber = 0;
                     while (rs.next()) {
-                        T e = resultMap.map(rs);
+                        T e = resultMap.map(rs, rowNumber++);
                         result.add(e);
                     }
                     return result;
@@ -114,7 +115,7 @@ public class SimpleJdbcTemplate {
             return (list.isEmpty()) ? Optional.empty() : Optional.ofNullable(list.get(0));
         }
 
-        public static final ResultMap<Map<String, Object>> mapResultMap = rs -> {
+        public static final ResultMap<Map<String, Object>> mapResultMap = (rs, rowNumber) -> {
             Map<String, Object> result = new HashMap<>();
             ResultSetMetaData metaData = rs.getMetaData();
             int columnCount = metaData.getColumnCount();
@@ -133,7 +134,7 @@ public class SimpleJdbcTemplate {
             return queryFirst(sql, params, mapResultMap);
         }
 
-        public static final ResultMap<DbRecord> recordResultMap = rs -> {
+        public static final ResultMap<DbRecord> recordResultMap = (rs, rowNumber) -> {
             DbRecord result = new DbRecord();
             ResultSetMetaData metaData = rs.getMetaData();
             int columnCount = metaData.getColumnCount();
@@ -153,26 +154,26 @@ public class SimpleJdbcTemplate {
         }
 
         public Optional<String> queryToString(String sql, Object... params) throws SQLException {
-            return queryFirst(sql, params, (ResultSet rs) -> rs.getString(1));
+            return queryFirst(sql, params, (ResultSet rs, int rowNumber) -> rs.getString(1));
         }
 
         public OptionalInt queryToInt(String sql, Object... params) throws SQLException {
-            Optional<Integer> result = queryFirst(sql, params, (ResultSet rs) -> rs.getInt(1));
+            Optional<Integer> result = queryFirst(sql, params, (ResultSet rs, int rowNumber) -> rs.getInt(1));
             return OptionalUtil.toOptionalInt(result);
         }
 
         public OptionalLong queryToLong(String sql, Object... params) throws SQLException {
-            Optional<Long> result = queryFirst(sql, params, (ResultSet rs) -> rs.getLong(1));
+            Optional<Long> result = queryFirst(sql, params, (ResultSet rs, int rowNumber) -> rs.getLong(1));
             return OptionalUtil.toOptionalLong(result);
         }
 
         public OptionalDouble queryToDouble(String sql, Object... params) throws SQLException {
-            Optional<Double> result = queryFirst(sql, params, (ResultSet rs) -> rs.getDouble(1));
+            Optional<Double> result = queryFirst(sql, params, (ResultSet rs, int rowNumber) -> rs.getDouble(1));
             return OptionalUtil.toOptionalDouble(result);
         }
 
         public Optional<BigDecimal> queryToBigDecimal(String sql, Object... params) throws SQLException {
-            return queryFirst(sql, params, (ResultSet rs) -> rs.getBigDecimal(1));
+            return queryFirst(sql, params, (ResultSet rs, int rowNumber) -> rs.getBigDecimal(1));
         }
 
         public int update(String sql, Object... params) throws SQLException {
@@ -224,7 +225,7 @@ public class SimpleJdbcTemplate {
         }
 
         @FunctionalInterface
-        public static interface IAtom<T extends Exception> {
+        public interface IAtom<T extends Exception> {
             @SuppressWarnings("all")
             void execute() throws SQLException, T;
         }
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/DateTimeUtil.java b/src/main/java/xyz/zhouxy/plusone/commons/util/DateTimeUtil.java
index 51099c0..2fcfcfc 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/DateTimeUtil.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/DateTimeUtil.java
@@ -9,33 +9,22 @@ import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.util.Calendar;
 import java.util.Date;
-import java.util.Objects;
 import java.util.TimeZone;
 
-import org.apache.commons.lang3.StringUtils;
+import xyz.zhouxy.plusone.commons.collection.SafeConcurrentHashMap;
 
 import xyz.zhouxy.plusone.commons.collection.MapWrapper;
 
 public class DateTimeUtil {
 
-    private static final MapWrapper<String, DateTimeFormatter> DATE_TIME_FORMATTER_CHCHE = MapWrapper
-            .<String, DateTimeFormatter>wrapHashMap()
-            .keyChecker(StringUtils::isNotBlank)
-            .valueChecker(Objects::nonNull)
+    private static final MapWrapper<String, DateTimeFormatter> DATE_TIME_FORMATTER_CACHE = MapWrapper
+            .<String, DateTimeFormatter>wrap(new SafeConcurrentHashMap<>())
+            .keyChecker(pattern -> Assert.isNotBlank(pattern, "The pattern could not be blank."))
+            .valueChecker(formatter -> Assert.notNull(formatter, "The formatter could not be null."))
             .build();
 
     public static DateTimeFormatter getDateTimeFormatter(String pattern) {
-        if (!DATE_TIME_FORMATTER_CHCHE.containsKey(pattern)) {
-            synchronized (DateTimeUtil.class) {
-                if (!DATE_TIME_FORMATTER_CHCHE.containsKey(pattern)) {
-                    DateTimeFormatter formatter = DateTimeFormatter.ofPattern(pattern);
-                    DATE_TIME_FORMATTER_CHCHE.put(pattern, formatter);
-                    return formatter;
-                }
-            }
-        }
-        return DATE_TIME_FORMATTER_CHCHE.get(pattern)
-                .orElseThrow(() -> new IllegalStateException("Formatter does not exist."));
+        return DATE_TIME_FORMATTER_CACHE.computeIfAbsent(pattern, DateTimeFormatter::ofPattern);
     }
 
     public static String toString(String pattern, ZonedDateTime dateTime) {
@@ -126,7 +115,7 @@ public class DateTimeUtil {
      * 只是不同时区的表示。
      * </p>
      * 
-     * @param dateTime {@link Date} 对象
+     * @param timeMillis 时间戳
      * @param zone     时区
      * @return 带时区信息的地区时间
      */
@@ -191,7 +180,7 @@ public class DateTimeUtil {
     /**
      * 获取时间戳在指定时区的地区时间。
      * 
-     * @param dateTime {@link Date} 对象
+     * @param timeMillis 时间戳
      * @param zone     时区
      * @return 地区时间
      */
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/MoreCollections.java b/src/main/java/xyz/zhouxy/plusone/commons/util/MoreCollections.java
index 5ad4142..1efca6a 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/MoreCollections.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/MoreCollections.java
@@ -60,7 +60,7 @@ public class MoreCollections {
         return toConcurrentHashMap(c, keyGenerator, c.size());
     }
 
-    public static <K, V> TreeMap<K, V> toTreeMap(Iterable<V> c, Function<? super V, K> keyGenerator) {
+    public static <K extends Comparable<? super K>, V> TreeMap<K, V> toTreeMap(Iterable<V> c, Function<? super V, K> keyGenerator) {
         TreeMap<K, V> map = new TreeMap<>();
         fillIntoEmptyMap(map, c, keyGenerator);
         return map;
@@ -106,7 +106,7 @@ public class MoreCollections {
         return toConcurrentHashMap(c, keyGenerator, c.length);
     }
 
-    public static <K, V> TreeMap<K, V> toTreeMap(V[] c, Function<? super V, K> keyGenerator) {
+    public static <K extends Comparable<? super K>, V> TreeMap<K, V> toTreeMap(V[] c, Function<? super V, K> keyGenerator) {
         TreeMap<K, V> map = new TreeMap<>();
         fillIntoEmptyMap(map, c, keyGenerator);
         return map;
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/OptionalUtil.java b/src/main/java/xyz/zhouxy/plusone/commons/util/OptionalUtil.java
index 4c852fa..1127ced 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/OptionalUtil.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/OptionalUtil.java
@@ -55,16 +55,16 @@ public class OptionalUtil {
     }
 
     /**
-     * 将 {@code Optional<Integer>} 转为 {@link OptionalInt}。
+     * 将 {@code Optional<Integer>} 对象转为 {@link OptionalInt} 对象。
      * <p>
      * {@code Optional<Integer>} 将整数包装了两次，改为使用 {@link OptionalInt} 包装其中的整数数据。
      * </p>
      * 
-     * @param value 包装对象
+     * @param optionalObj {@code Optional<Integer>} 对象
      * @return {@link OptionalInt} 实例
      */
-    public static OptionalInt toOptionalInt(Optional<Integer> objectOptional) {
-        return optionalOf(objectOptional.orElse(null));
+    public static OptionalInt toOptionalInt(Optional<Integer> optionalObj) {
+        return optionalOf(optionalObj.orElse(null));
     }
 
     /**
@@ -87,11 +87,11 @@ public class OptionalUtil {
      * {@code Optional<Long>} 将整数包装了两次，改为使用 {@link OptionalLong} 包装其中的整数数据。
      * </p>
      * 
-     * @param value 包装对象
+     * @param optionalObj 包装对象
      * @return {@link OptionalLong} 实例
      */
-    public static OptionalLong toOptionalLong(Optional<Long> objectOptional) {
-        return optionalOf(objectOptional.orElse(null));
+    public static OptionalLong toOptionalLong(Optional<Long> optionalObj) {
+        return optionalOf(optionalObj.orElse(null));
     }
 
     /**
@@ -114,11 +114,11 @@ public class OptionalUtil {
      * {@code Optional<Double>} 将整数包装了两次，改为使用 {@link OptionalDouble} 包装其中的整数数据。
      * </p>
      * 
-     * @param value 包装对象
+     * @param optionalObj 包装对象
      * @return {@link OptionalDouble} 实例
      */
-    public static OptionalDouble toOptionalDouble(Optional<Double> objectOptional) {
-        return optionalOf(objectOptional.orElse(null));
+    public static OptionalDouble toOptionalDouble(Optional<Double> optionalObj) {
+        return optionalOf(optionalObj.orElse(null));
     }
 
     /**
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/PagingAndSortingQueryParams.java b/src/main/java/xyz/zhouxy/plusone/commons/util/PagingAndSortingQueryParams.java
index b34bea2..3f4a88b 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/PagingAndSortingQueryParams.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/PagingAndSortingQueryParams.java
@@ -51,10 +51,11 @@ public class PagingAndSortingQueryParams {
     }
 
     public PagingAndSortingQueryParams(String... sortableColNames) {
+        Set<String> sortableColNameSet = new HashSet<>(sortableColNames.length);
         for (String colName : sortableColNames) {
             Assert.isNotBlank(colName, "Column name must has text.");
+            sortableColNameSet.add(colName);
         }
-        Set<String> sortableColNameSet = new HashSet<>(sortableColNames.length);
         this.sortableColNames = Collections.unmodifiableSet(sortableColNameSet);
     }
 
diff --git a/src/main/java/xyz/zhouxy/plusone/commons/util/SnowflakeIdGenerator.java b/src/main/java/xyz/zhouxy/plusone/commons/util/SnowflakeIdGenerator.java
index 4e410b2..810eee7 100644
--- a/src/main/java/xyz/zhouxy/plusone/commons/util/SnowflakeIdGenerator.java
+++ b/src/main/java/xyz/zhouxy/plusone/commons/util/SnowflakeIdGenerator.java
@@ -42,10 +42,10 @@ public class SnowflakeIdGenerator {
     private static final long SEQUENCE_MASK = -1L ^ (-1L << SEQUENCE_BITS);
 
     /** 工作机器 ID (0~31) */
-    private long workerId;
+    private final long workerId;
 
     /** 数据中心 ID (0~31) */
-    private long datacenterId;
+    private final long datacenterId;
 
     /** 毫秒内序列 (0~4095) */
     private long sequence = 0L;
@@ -78,7 +78,6 @@ public class SnowflakeIdGenerator {
      * 获得下一个ID (该方法是线程安全的)
      * 
      * @return SnowflakeId
-     * @throws InterruptedException
      */
     public synchronized long nextId() {
         long timestamp = timeGen();
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/SimpleJdbcTemplateTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/SimpleJdbcTemplateTests.java
index 247cd4b..e8822e0 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/SimpleJdbcTemplateTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/SimpleJdbcTemplateTests.java
@@ -28,7 +28,7 @@ class SimpleJdbcTemplateTests {
 
     private static final Logger log = LoggerFactory.getLogger(SimpleJdbcTemplateTests.class);
 
-    DataSource dataSource;
+    final DataSource dataSource;
 
     String[] cStruct = {
             "id",
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/TreeBuilderTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/TreeBuilderTests.java
index 446ec35..dd2c063 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/TreeBuilderTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/TreeBuilderTests.java
@@ -31,7 +31,7 @@ class TreeBuilderTests {
                 MenuItem.of("C", "C2", "二级菜单C2", "/c/c2"),
                 MenuItem.of("C", "C3", "二级菜单C3", "/c/c3")
         );
-        List<Menu> menuTree = new TreeBuilder<Menu, String>(
+        List<Menu> menuTree = new TreeBuilder<>(
                 menus,
                 Menu::getMenuCode,
                 Menu::getParentMenuCode,