fix code

hutool-db/src/main/java/cn/hutool/db/ThreadLocalConnection.java

@@ -1,12 +1,11 @@
 package cn.hutool.db;
 
+import javax.sql.DataSource;
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.HashMap;
 import java.util.Map;
 
-import javax.sql.DataSource;
-
 /**
  * 线程相关的数据库连接持有器<br>
  * 此对象为单例类，用于存储线程相关的Connection对象。<br>
@@ -61,7 +60,7 @@ public enum ThreadLocalConnection {
 	public static class GroupedConnection {
 
 		/** 连接的Map，考虑到大部分情况是单数据库，故此处初始大小1 */
-		private Map<DataSource, Connection> connMap = new HashMap<>(1, 1);
+		private final Map<DataSource, Connection> connMap = new HashMap<>(1, 1);
 
 		/**
 		 * 获取连接，如果获取的连接为空或者已被关闭，重新创建连接

hutool-db/src/main/java/cn/hutool/db/dialect/DialectFactory.java

@@ -1,11 +1,5 @@
 package cn.hutool.db.dialect;
 
-import java.sql.Connection;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-
-import javax.sql.DataSource;
-
 import cn.hutool.core.util.ClassLoaderUtil;
 import cn.hutool.core.util.StrUtil;
 import cn.hutool.db.dialect.impl.AnsiSqlDialect;
@@ -17,6 +11,11 @@ import cn.hutool.db.dialect.impl.SqlServer2012Dialect;
 import cn.hutool.db.dialect.impl.Sqlite3Dialect;
 import cn.hutool.log.StaticLog;
 
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
 /**
  * 方言工厂类
  * 
@@ -26,35 +25,35 @@ import cn.hutool.log.StaticLog;
 public class DialectFactory {
 	
 	/** JDBC 驱动 MySQL */
-	public final static String DRIVER_MYSQL = "com.mysql.jdbc.Driver";
+	public static final String DRIVER_MYSQL = "com.mysql.jdbc.Driver";
 	/** JDBC 驱动 MySQL，在6.X版本中变动驱动类名，且使用SPI机制 */
-	public final static String DRIVER_MYSQL_V6 = "com.mysql.cj.jdbc.Driver";
+	public static final String DRIVER_MYSQL_V6 = "com.mysql.cj.jdbc.Driver";
 	/** JDBC 驱动 Oracle */
-	public final static String DRIVER_ORACLE = "oracle.jdbc.OracleDriver";
+	public static final String DRIVER_ORACLE = "oracle.jdbc.OracleDriver";
 	/** JDBC 驱动 Oracle，旧版使用 */
-	public final static String DRIVER_ORACLE_OLD = "oracle.jdbc.driver.OracleDriver";
+	public static final String DRIVER_ORACLE_OLD = "oracle.jdbc.driver.OracleDriver";
 	/** JDBC 驱动 PostgreSQL */
-	public final static String DRIVER_POSTGRESQL = "org.postgresql.Driver";
+	public static final String DRIVER_POSTGRESQL = "org.postgresql.Driver";
 	/** JDBC 驱动 SQLLite3 */
-	public final static String DRIVER_SQLLITE3 = "org.sqlite.JDBC";
+	public static final String DRIVER_SQLLITE3 = "org.sqlite.JDBC";
 	/** JDBC 驱动 SQLServer */
-	public final static String DRIVER_SQLSERVER = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
+	public static final String DRIVER_SQLSERVER = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
 	/** JDBC 驱动 Hive */
-	public final static String DRIVER_HIVE = "org.apache.hadoop.hive.jdbc.HiveDriver";
+	public static final String DRIVER_HIVE = "org.apache.hadoop.hive.jdbc.HiveDriver";
 	/** JDBC 驱动 Hive2 */
-	public final static String DRIVER_HIVE2 = "org.apache.hive.jdbc.HiveDriver";
+	public static final String DRIVER_HIVE2 = "org.apache.hive.jdbc.HiveDriver";
 	/** JDBC 驱动 H2 */
-	public final static String DRIVER_H2 = "org.h2.Driver";
+	public static final String DRIVER_H2 = "org.h2.Driver";
 	/** JDBC 驱动 Derby */
-	public final static String DRIVER_DERBY = "org.apache.derby.jdbc.ClientDriver";
+	public static final String DRIVER_DERBY = "org.apache.derby.jdbc.ClientDriver";
 	/** JDBC 驱动 Derby嵌入式 */
-	public final static String DRIVER_DERBY_EMBEDDED = "org.apache.derby.jdbc.EmbeddedDriver";
+	public static final String DRIVER_DERBY_EMBEDDED = "org.apache.derby.jdbc.EmbeddedDriver";
 	/** JDBC 驱动 HSQLDB */
-	public final static String DRIVER_HSQLDB = "org.hsqldb.jdbc.JDBCDriver";
+	public static final String DRIVER_HSQLDB = "org.hsqldb.jdbc.JDBCDriver";
 	/** JDBC 驱动 达梦7 */
-	public final static String DRIVER_DM7 = "dm.jdbc.driver.DmDriver";
+	public static final String DRIVER_DM7 = "dm.jdbc.driver.DmDriver";
 	
-	private static Map<DataSource, Dialect> dialectPool = new ConcurrentHashMap<>();
+	private static final Map<DataSource, Dialect> DIALECT_POOL = new ConcurrentHashMap<>();
 
 	private DialectFactory() {
 	}
@@ -150,15 +149,15 @@ public class DialectFactory {
 	 * @return {@link Dialect}方言
 	 */
 	public static Dialect getDialect(DataSource ds) {
-		Dialect dialect = dialectPool.get(ds);
+		Dialect dialect = DIALECT_POOL.get(ds);
 		if(null == dialect) {
 			// 数据源作为锁的意义在于：不同数据源不会导致阻塞，相同数据源获取方言时可保证互斥
 			//noinspection SynchronizationOnLocalVariableOrMethodParameter
 			synchronized (ds) {
-				dialect = dialectPool.get(ds);
+				dialect = DIALECT_POOL.get(ds);
 				if(null == dialect) {
 					dialect = newDialect(ds);
-					dialectPool.put(ds, dialect);
+					DIALECT_POOL.put(ds, dialect);
 				}
 			}
 		}

hutool-db/src/main/java/cn/hutool/db/ds/DataSourceWrapper.java

@@ -1,5 +1,8 @@
 package cn.hutool.db.ds;
 
+import cn.hutool.core.io.IoUtil;
+
+import javax.sql.DataSource;
 import java.io.Closeable;
 import java.io.PrintWriter;
 import java.sql.Connection;
@@ -7,10 +10,6 @@ import java.sql.SQLException;
 import java.sql.SQLFeatureNotSupportedException;
 import java.util.logging.Logger;
 
-import javax.sql.DataSource;
-
-import cn.hutool.core.io.IoUtil;
-
 /**
  * {@link DataSource} 数据源实现包装，通过包装，提供基本功能外的额外功能和参数持有，包括：
  *
@@ -23,8 +22,8 @@ import cn.hutool.core.io.IoUtil;
  */
 public class DataSourceWrapper implements DataSource, Closeable, Cloneable {
 
-	private DataSource ds;
-	private String driver;
+	private final DataSource ds;
+	private final String driver;
 
 	/**
 	 * 包装指定的DataSource

hutool-db/src/main/java/cn/hutool/db/ds/pooled/DbSetting.java

@@ -17,7 +17,7 @@ public class DbSetting {
 	/** 默认的数据库连接配置文件路径 */
 	public final static String DEFAULT_DB_CONFIG_PATH = "config/db.setting";
 
-	private Setting setting;
+	private final Setting setting;
 
 	/**
 	 * 构造

hutool-db/src/main/java/cn/hutool/db/ds/pooled/PooledConnection.java

@@ -1,11 +1,11 @@
 package cn.hutool.db.ds.pooled;
 
+import cn.hutool.db.DbUtil;
+
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
 
-import cn.hutool.db.DbUtil;
-
 /**
  * 池化
  * @author Looly
@@ -13,7 +13,7 @@ import cn.hutool.db.DbUtil;
  */
 public class PooledConnection extends ConnectionWraper{
 	
-	private PooledDataSource ds;
+	private final PooledDataSource ds;
 	private boolean isClosed;
 	
 	public PooledConnection(PooledDataSource ds) throws SQLException {

hutool-db/src/main/java/cn/hutool/db/ds/pooled/PooledDataSource.java

@@ -1,11 +1,5 @@
 package cn.hutool.db.ds.pooled;
 
-import java.io.IOException;
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.util.LinkedList;
-import java.util.Queue;
-
 import cn.hutool.core.collection.CollectionUtil;
 import cn.hutool.core.io.IoUtil;
 import cn.hutool.core.thread.ThreadUtil;
@@ -13,6 +7,11 @@ import cn.hutool.core.util.StrUtil;
 import cn.hutool.db.DbRuntimeException;
 import cn.hutool.db.ds.simple.AbstractDataSource;
 
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.LinkedList;
+import java.util.Queue;
+
 /**
  * 池化数据源
  * 
@@ -24,7 +23,7 @@ public class PooledDataSource extends AbstractDataSource {
 	private Queue<PooledConnection> freePool;
 	private int activeCount; // 活跃连接数
 
-	private DbConfig config;
+	private final DbConfig config;
 
 	/**
 	 * 获得一个数据源
@@ -79,7 +78,7 @@ public class PooledDataSource extends AbstractDataSource {
 	 */
 	public PooledDataSource(DbConfig config) {
 		this.config = config;
-		freePool = new LinkedList<PooledConnection>();
+		freePool = new LinkedList<>();
 		int initialSize = config.getInitialSize();
 		try {
 			while (initialSize-- > 0) {
@@ -146,7 +145,7 @@ public class PooledDataSource extends AbstractDataSource {
 	}
 
 	@Override
-	synchronized public void close() throws IOException {
+	synchronized public void close() {
 		if (CollectionUtil.isNotEmpty(this.freePool)) {
 			for (PooledConnection pooledConnection : freePool) {
 				pooledConnection.release();
@@ -157,7 +156,7 @@ public class PooledDataSource extends AbstractDataSource {
 	}
 
 	@Override
-	protected void finalize() throws Throwable {
+	protected void finalize() {
 		IoUtil.close(this);
 	}
 

hutool-db/src/main/java/cn/hutool/db/handler/EntityHandler.java

@@ -1,11 +1,11 @@
 package cn.hutool.db.handler;
 
+import cn.hutool.db.Entity;
+
 import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 
-import cn.hutool.db.Entity;
-
 /**
  * Entity对象处理器，只处理第一条数据
  * 
@@ -16,7 +16,7 @@ public class EntityHandler implements RsHandler<Entity>{
 	private static final long serialVersionUID = -8742432871908355992L;
 
 	/** 是否大小写不敏感 */
-	private boolean caseInsensitive;
+	private final boolean caseInsensitive;
 
 	/**
 	 * 创建一个 EntityHandler对象

hutool-db/src/main/java/cn/hutool/db/handler/EntityListHandler.java

@@ -1,12 +1,12 @@
 package cn.hutool.db.handler;
 
+import cn.hutool.db.Entity;
+
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 
-import cn.hutool.db.Entity;
-
 /**
  * 结果集处理类 ，处理出的结果为Entity列表
  * @author loolly
@@ -16,7 +16,7 @@ public class EntityListHandler implements RsHandler<List<Entity>>{
 	private static final long serialVersionUID = -2846240126316979895L;
 	
 	/** 是否大小写不敏感 */
-	private boolean caseInsensitive;
+	private final boolean caseInsensitive;
 	
 	/**
 	 * 创建一个 EntityListHandler对象

hutool-db/src/main/java/cn/hutool/db/handler/EntitySetHandler.java

@@ -1,11 +1,11 @@
 package cn.hutool.db.handler;
 
+import cn.hutool.db.Entity;
+
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.LinkedHashSet;
 
-import cn.hutool.db.Entity;
-
 /**
  * 结果集处理类 ，处理出的结果为Entity列表，结果不能重复（按照Entity对象去重）
  * @author loolly
@@ -15,7 +15,7 @@ public class EntitySetHandler implements RsHandler<LinkedHashSet<Entity>>{
 	private static final long serialVersionUID = 8191723216703506736L;
 
 	/** 是否大小写不敏感 */
-	private boolean caseInsensitive;
+	private final boolean caseInsensitive;
 
 	/**
 	 * 创建一个 EntityHandler对象

hutool-db/src/main/java/cn/hutool/db/handler/PageResultHandler.java

@@ -1,11 +1,11 @@
 package cn.hutool.db.handler;
 
-import java.sql.ResultSet;
-import java.sql.SQLException;
-
 import cn.hutool.db.Entity;
 import cn.hutool.db.PageResult;
 
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
 /**
  * 分页结果集处理类 ，处理出的结果为PageResult
  *
@@ -14,11 +14,11 @@ import cn.hutool.db.PageResult;
 public class PageResultHandler implements RsHandler<PageResult<Entity>> {
 	private static final long serialVersionUID = -1474161855834070108L;
 
-	private PageResult<Entity> pageResult;
+	private final PageResult<Entity> pageResult;
 	/**
 	 * 是否大小写不敏感
 	 */
-	private boolean caseInsensitive;
+	private final boolean caseInsensitive;
 
 	/**
 	 * 创建一个 EntityHandler对象<br>

hutool-db/src/main/java/cn/hutool/db/meta/JdbcType.java

@@ -4,7 +4,10 @@ import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
 /**
+ * JDBC中字段类型枚举
+ *
  * @author Clinton Begin
+ * @see java.sql.Types
  */
 public enum JdbcType {
 	ARRAY(java.sql.Types.ARRAY), //
@@ -60,10 +63,10 @@ public enum JdbcType {
 		this.typeCode = code;
 	}
 
-	private static Map<Integer, JdbcType> codeMap = new ConcurrentHashMap<>(100, 1);
+	private static final Map<Integer, JdbcType> CODE_MAP = new ConcurrentHashMap<>(100, 1);
 	static {
 		for (JdbcType type : JdbcType.values()) {
-			codeMap.put(type.typeCode, type);
+			CODE_MAP.put(type.typeCode, type);
 		}
 	}
 
@@ -74,7 +77,7 @@ public enum JdbcType {
 	 * @return {@link JdbcType}
 	 */
 	public static JdbcType valueOf(int code) {
-		return codeMap.get(code);
+		return CODE_MAP.get(code);
 	}
 	
 }

hutool-db/src/main/java/cn/hutool/db/meta/Table.java

@@ -21,8 +21,8 @@ public class Table implements Serializable, Cloneable {
 	/** 注释 */
 	private String comment;
 	/** 主键字段名列表 */
-	private Set<String> pkNames = new LinkedHashSet<String>();
-	private Map<String, Column> columns = new LinkedHashMap<>();
+	private Set<String> pkNames = new LinkedHashSet<>();
+	private final Map<String, Column> columns = new LinkedHashMap<>();
 
 	public static Table create(String tableName) {
 		return new Table(tableName);

hutool-db/src/main/java/cn/hutool/db/meta/TableType.java

@@ -14,7 +14,7 @@ public enum TableType {
 	ALIAS("ALIAS"),
 	SYNONYM("SYNONYM");
 	
-	private String value;
+	private final String value;
 	
 	/**
 	 * 构造

hutool-db/src/main/java/cn/hutool/db/nosql/mongo/MongoFactory.java

@@ -1,13 +1,14 @@
 package cn.hutool.db.nosql.mongo;
 
+import cn.hutool.core.collection.CollectionUtil;
+import cn.hutool.core.util.ArrayUtil;
+import cn.hutool.core.util.RuntimeUtil;
+import cn.hutool.setting.Setting;
+
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
-import cn.hutool.core.collection.CollectionUtil;
-import cn.hutool.core.util.ArrayUtil;
-import cn.hutool.setting.Setting;
-
 /**
  * MongoDB工厂类，用于创建
  * @author looly
@@ -19,16 +20,11 @@ public class MongoFactory {
 	private final static String GROUP_SEPRATER = ",";
 	
 	/** 数据源池 */
-	private static Map<String, MongoDS> dsMap = new ConcurrentHashMap<>();
+	private static final Map<String, MongoDS> DS_MAP = new ConcurrentHashMap<>();
 
 	// JVM关闭前关闭MongoDB连接
 	static {
-		Runtime.getRuntime().addShutdownHook(new Thread() {
-			@Override
-			public void run() {
-				MongoFactory.closeAll();
-			}
-		});
+		RuntimeUtil.addShutdownHook(MongoFactory::closeAll);
 	}
 
 	// ------------------------------------------------------------------------ Get DS start
@@ -41,11 +37,11 @@ public class MongoFactory {
 	 */
 	public static MongoDS getDS(String host, int port) {
 		final String key = host + ":" + port;
-		MongoDS ds = dsMap.get(key);
+		MongoDS ds = DS_MAP.get(key);
 		if (null == ds) {
 			// 没有在池中加入之
 			ds = new MongoDS(host, port);
-			dsMap.put(key, ds);
+			DS_MAP.put(key, ds);
 		}
 
 		return ds;
@@ -60,11 +56,11 @@ public class MongoFactory {
 	 */
 	public static MongoDS getDS(String... groups) {
 		final String key = ArrayUtil.join(groups, GROUP_SEPRATER);
-		MongoDS ds = dsMap.get(key);
+		MongoDS ds = DS_MAP.get(key);
 		if (null == ds) {
 			// 没有在池中加入之
 			ds = new MongoDS(groups);
-			dsMap.put(key, ds);
+			DS_MAP.put(key, ds);
 		}
 
 		return ds;
@@ -77,7 +73,7 @@ public class MongoFactory {
 	 * @return MongoDB连接
 	 */
 	public static MongoDS getDS(Collection<String> groups) {
-		return getDS(groups.toArray(new String[groups.size()]));
+		return getDS(groups.toArray(new String[0]));
 	}
 
 	/**
@@ -89,11 +85,11 @@ public class MongoFactory {
 	 */
 	public static MongoDS getDS(Setting setting, String... groups) {
 		final String key = setting.getSettingPath() + GROUP_SEPRATER + ArrayUtil.join(groups, GROUP_SEPRATER);
-		MongoDS ds = dsMap.get(key);
+		MongoDS ds = DS_MAP.get(key);
 		if (null == ds) {
 			// 没有在池中加入之
 			ds = new MongoDS(setting, groups);
-			dsMap.put(key, ds);
+			DS_MAP.put(key, ds);
 		}
 
 		return ds;
@@ -107,7 +103,7 @@ public class MongoFactory {
 	 * @return MongoDB连接
 	 */
 	public static MongoDS getDS(Setting setting, Collection<String> groups) {
-		return getDS(setting, groups.toArray(new String[groups.size()]));
+		return getDS(setting, groups.toArray(new String[0]));
 	}
 	// ------------------------------------------------------------------------ Get DS ends
 	
@@ -115,11 +111,11 @@ public class MongoFactory {
 	 * 关闭全部连接
 	 */
 	public static void closeAll() {
-		if(CollectionUtil.isNotEmpty(dsMap)){
-			for(MongoDS ds : dsMap.values()) {
+		if(CollectionUtil.isNotEmpty(DS_MAP)){
+			for(MongoDS ds : DS_MAP.values()) {
 				ds.close();
 			}
-			dsMap.clear();
+			DS_MAP.clear();
 		}
 	}
 }

hutool-db/src/main/java/cn/hutool/db/sql/Condition.java

@@ -1,37 +1,40 @@
 package cn.hutool.db.sql;
 
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.List;
-
 import cn.hutool.core.clone.CloneSupport;
-import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.convert.Convert;
 import cn.hutool.core.text.StrSpliter;
 import cn.hutool.core.util.ArrayUtil;
 import cn.hutool.core.util.CharUtil;
 import cn.hutool.core.util.StrUtil;
 
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+
 /**
  * 条件对象<br>
- * 
- * @author Looly
  *
+ * @author Looly
  */
 public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * SQL中 LIKE 语句查询方式<br>
-	 * 
-	 * @author Looly
 	 *
+	 * @author Looly
 	 */
 	public enum LikeType {
-		/** 以给定值开头，拼接后的SQL "value%" */
+		/**
+		 * 以给定值开头，拼接后的SQL "value%"
+		 */
 		StartWith,
-		/** 以给定值开头，拼接后的SQL "%value" */
+		/**
+		 * 以给定值开头，拼接后的SQL "%value"
+		 */
 		EndWith,
-		/** 包含给定值，拼接后的SQL "%value%" */
+		/**
+		 * 包含给定值，拼接后的SQL "%value%"
+		 */
 		Contains
 	}
 
@@ -44,21 +47,31 @@ public class Condition extends CloneSupport<Condition> {
 
 	private static final String VALUE_NULL = "NULL";
 
-	/** 字段 */
+	/**
+	 * 字段
+	 */
 	private String field;
-	/** 运算符（大于号，小于号，等于号 like 等） */
+	/**
+	 * 运算符（大于号，小于号，等于号 like 等）
+	 */
 	private String operator;
-	/** 值 */
+	/**
+	 * 值
+	 */
 	private Object value;
-	/** 是否使用条件值占位符 */
+	/**
+	 * 是否使用条件值占位符
+	 */
 	private boolean isPlaceHolder = true;
-	/** between firstValue and secondValue */
+	/**
+	 * between firstValue and secondValue
+	 */
 	private Object secondValue;
 
 	/**
 	 * 解析为Condition
-	 * 
-	 * @param field 字段名
+	 *
+	 * @param field      字段名
 	 * @param expression 表达式或普通值
 	 * @return Condition
 	 */
@@ -67,6 +80,7 @@ public class Condition extends CloneSupport<Condition> {
 	}
 
 	// --------------------------------------------------------------- Constructor start
+
 	/**
 	 * 构造
 	 */
@@ -75,7 +89,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 构造
-	 * 
+	 *
 	 * @param isPlaceHolder 是否使用条件值占位符
 	 */
 	public Condition(boolean isPlaceHolder) {
@@ -84,7 +98,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 构造，使用等于表达式（运算符是=）
-	 * 
+	 *
 	 * @param field 字段
 	 * @param value 值
 	 */
@@ -95,10 +109,10 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 构造
-	 * 
-	 * @param field 字段
+	 *
+	 * @param field    字段
 	 * @param operator 运算符（大于号，小于号，等于号 like 等）
-	 * @param value 值
+	 * @param value    值
 	 */
 	public Condition(String field, String operator, Object value) {
 		this.field = field;
@@ -108,9 +122,9 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 构造
-	 * 
-	 * @param field 字段
-	 * @param value 值
+	 *
+	 * @param field    字段
+	 * @param value    值
 	 * @param likeType {@link LikeType}
 	 */
 	public Condition(String field, String value, LikeType likeType) {
@@ -121,6 +135,7 @@ public class Condition extends CloneSupport<Condition> {
 	// --------------------------------------------------------------- Constructor end
 
 	// --------------------------------------------------------------- Getters and Setters start
+
 	/**
 	 * @return 字段
 	 */
@@ -130,7 +145,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 设置字段名
-	 * 
+	 *
 	 * @param field 字段名
 	 */
 	public void setField(String field) {
@@ -140,7 +155,7 @@ public class Condition extends CloneSupport<Condition> {
 	/**
 	 * 获得运算符<br>
 	 * 大于号，小于号，等于号 等
-	 * 
+	 *
 	 * @return 运算符
 	 */
 	public String getOperator() {
@@ -150,7 +165,7 @@ public class Condition extends CloneSupport<Condition> {
 	/**
 	 * 设置运算符<br>
 	 * 大于号，小于号，等于号 等
-	 * 
+	 *
 	 * @param operator 运算符
 	 */
 	public void setOperator(String operator) {
@@ -159,7 +174,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 获得值
-	 * 
+	 *
 	 * @return 值
 	 */
 	public Object getValue() {
@@ -168,7 +183,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 设置值，不解析表达式
-	 * 
+	 *
 	 * @param value 值
 	 */
 	public void setValue(Object value) {
@@ -177,8 +192,8 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 设置值
-	 * 
-	 * @param value 值
+	 *
+	 * @param value   值
 	 * @param isParse 是否解析值表达式
 	 */
 	public void setValue(Object value, boolean isParse) {
@@ -190,7 +205,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 是否使用条件占位符
-	 * 
+	 *
 	 * @return 是否使用条件占位符
 	 */
 	public boolean isPlaceHolder() {
@@ -199,7 +214,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 设置是否使用条件占位符
-	 * 
+	 *
 	 * @param isPlaceHolder 是否使用条件占位符
 	 */
 	public void setPlaceHolder(boolean isPlaceHolder) {
@@ -218,7 +233,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 是否IN条件
-	 * 
+	 *
 	 * @return 是否IN条件
 	 * @since 4.0.1
 	 */
@@ -228,7 +243,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 是否IS条件
-	 * 
+	 *
 	 * @return 是否IS条件
 	 * @since 4.0.1
 	 */
@@ -238,7 +253,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 检查值是否为null，如果为null转换为 "IS NULL"形式
-	 * 
+	 *
 	 * @return this
 	 */
 	public Condition checkValueNull() {
@@ -276,7 +291,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 转换为条件字符串，并回填占位符对应的参数值
-	 * 
+	 *
 	 * @param paramValues 参数列表，用于回填占位符对应参数值
 	 * @return 条件字符串
 	 */
@@ -297,7 +312,7 @@ public class Condition extends CloneSupport<Condition> {
 			if (isPlaceHolder() && false == isOperatorIs()) {
 				// 使用条件表达式占位符，条件表达式并不适用于 IS NULL
 				conditionStrBuilder.append(" ?");
-				if(null != paramValues) {
+				if (null != paramValues) {
 					paramValues.add(this.value);
 				}
 			} else {
@@ -310,19 +325,20 @@ public class Condition extends CloneSupport<Condition> {
 	}
 
 	// ----------------------------------------------------------------------------------------------- Private method start
+
 	/**
 	 * 构建BETWEEN语句中的值部分<br>
 	 * 开头必须加空格，类似：" ? AND ?" 或者 " 1 AND 2"
-	 * 
+	 *
 	 * @param conditionStrBuilder 条件语句构建器
-	 * @param paramValues 参数集合，用于参数占位符对应参数回填
+	 * @param paramValues         参数集合，用于参数占位符对应参数回填
 	 */
 	private void buildValuePartForBETWEEN(StringBuilder conditionStrBuilder, List<Object> paramValues) {
 		// BETWEEN x AND y 的情况，两个参数
 		if (isPlaceHolder()) {
 			// 使用条件表达式占位符
 			conditionStrBuilder.append(" ?");
-			if(null != paramValues) {
+			if (null != paramValues) {
 				paramValues.add(this.value);
 			}
 		} else {
@@ -335,7 +351,7 @@ public class Condition extends CloneSupport<Condition> {
 		if (isPlaceHolder()) {
 			// 使用条件表达式占位符
 			conditionStrBuilder.append(" ?");
-			if(null != paramValues) {
+			if (null != paramValues) {
 				paramValues.add(this.secondValue);
 			}
 		} else {
@@ -347,9 +363,9 @@ public class Condition extends CloneSupport<Condition> {
 	/**
 	 * 构建IN语句中的值部分<br>
 	 * 开头必须加空格，类似：" (?,?,?)" 或者 " (1,2,3,4)"
-	 * 
+	 *
 	 * @param conditionStrBuilder 条件语句构建器
-	 * @param paramValues 参数集合，用于参数占位符对应参数回填
+	 * @param paramValues         参数集合，用于参数占位符对应参数回填
 	 */
 	private void buildValuePartForIN(StringBuilder conditionStrBuilder, List<Object> paramValues) {
 		conditionStrBuilder.append(" (");
@@ -361,12 +377,9 @@ public class Condition extends CloneSupport<Condition> {
 				valuesForIn = StrUtil.split((CharSequence) value, ',');
 			} else {
 				valuesForIn = Arrays.asList(Convert.convert(String[].class, value));
-				if (null == valuesForIn) {
-					valuesForIn = CollUtil.newArrayList(Convert.toStr(value));
-				}
 			}
 			conditionStrBuilder.append(StrUtil.repeatAndJoin("?", valuesForIn.size(), ","));
-			if(null != paramValues) {
+			if (null != paramValues) {
 				paramValues.addAll(valuesForIn);
 			}
 		} else {
@@ -461,7 +474,7 @@ public class Condition extends CloneSupport<Condition> {
 
 	/**
 	 * 去掉包围在字符串两端的单引号或双引号
-	 * 
+	 *
 	 * @param value 值
 	 * @return 去掉引号后的值
 	 */
@@ -474,15 +487,15 @@ public class Condition extends CloneSupport<Condition> {
 		int from = 0;
 		int to = value.length();
 		char startChar = value.charAt(0);
-		char endChar = value.charAt(to - 1);
+		char endChar = value.charAt(value.length() - 1);
 		if (startChar == endChar) {
 			if ('\'' == startChar || '"' == startChar) {
 				from = 1;
-				to = to - 1;
+				to--;
 			}
 		}
 
-		if (from == 0 && to == value.length()) {
+		if (from == 0) {
 			// 并不包含，返回原值
 			return value;
 		}

hutool-db/src/main/java/cn/hutool/db/sql/NamedSql.java

@@ -1,12 +1,12 @@
 package cn.hutool.db.sql;
 
+import cn.hutool.core.text.StrBuilder;
+import cn.hutool.core.util.StrUtil;
+
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
-import cn.hutool.core.text.StrBuilder;
-import cn.hutool.core.util.StrUtil;
-
 /**
  * 使用命名占位符的SQL，例如：select * from table where field1=:name1<br>
  * 支持的占位符格式为：
@@ -22,7 +22,7 @@ import cn.hutool.core.util.StrUtil;
 public class NamedSql {
 
 	private String sql;
-	private List<Object> params;
+	private final List<Object> params;
 
 	/**
 	 * 构造

hutool-db/src/main/java/cn/hutool/db/sql/SqlFormatter.java

@@ -70,8 +70,8 @@ public class SqlFormatter {
 		boolean afterInsert = false;
 		int inFunction = 0;
 		int parensSinceSelect = 0;
-		private LinkedList<Integer> parenCounts = new LinkedList<>();
-		private LinkedList<Boolean> afterByOrFromOrSelects = new LinkedList<>();
+		private final LinkedList<Integer> parenCounts = new LinkedList<>();
+		private final LinkedList<Boolean> afterByOrFromOrSelects = new LinkedList<>();
 
 		int indent = 1;
 
@@ -273,14 +273,13 @@ public class SqlFormatter {
 			}
 			if (this.inFunction > 0) {
 				this.inFunction -= 1;
-				out();
 			} else {
 				if (!this.afterByOrSetOrFromOrSelect) {
 					this.indent -= 1;
 					newline();
 				}
-				out();
 			}
+			out();
 			this.beginLine = false;
 		}
 

hutool-db/src/main/java/cn/hutool/db/sql/SqlUtil.java

@@ -1,5 +1,12 @@
 package cn.hutool.db.sql;
 
+import cn.hutool.core.io.IoUtil;
+import cn.hutool.core.util.CharsetUtil;
+import cn.hutool.core.util.StrUtil;
+import cn.hutool.db.DbRuntimeException;
+import cn.hutool.db.Entity;
+import cn.hutool.db.sql.Condition.LikeType;
+
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.Reader;
@@ -12,13 +19,6 @@ import java.sql.SQLException;
 import java.util.List;
 import java.util.Map.Entry;
 
-import cn.hutool.core.io.IoUtil;
-import cn.hutool.core.util.CharsetUtil;
-import cn.hutool.core.util.StrUtil;
-import cn.hutool.db.DbRuntimeException;
-import cn.hutool.db.Entity;
-import cn.hutool.db.sql.Condition.LikeType;
-
 /**
  * SQL相关工具类，包括相关SQL语句拼接等
  *
@@ -105,7 +105,7 @@ public class SqlUtil {
 	 */
 	public static String buildLikeValue(String value, LikeType likeType, boolean withLikeKeyword) {
 		if (null == value) {
-			return value;
+			return null;
 		}
 
 		StringBuilder likeValue = StrUtil.builder(withLikeKeyword ? "LIKE " : "");

hutool-db/src/main/java/cn/hutool/db/sql/Wrapper.java

@@ -1,15 +1,15 @@
 package cn.hutool.db.sql;
 
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Map.Entry;
-
 import cn.hutool.core.collection.CollectionUtil;
 import cn.hutool.core.lang.Editor;
 import cn.hutool.core.util.ArrayUtil;
 import cn.hutool.core.util.StrUtil;
 import cn.hutool.db.Entity;
 
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Map.Entry;
+
 /**
  * 包装器<br>
  * 主要用于字段名的包装（在字段名的前后加字符，例如反引号来避免与数据库的关键字冲突）
@@ -135,7 +135,7 @@ public class Wrapper {
 			return fields;
 		}
 		
-		return Arrays.asList(wrap(fields.toArray(new String[fields.size()])));
+		return Arrays.asList(wrap(fields.toArray(new String[0])));
 	}
 	
 	/**

hutool-db/src/main/java/cn/hutool/db/transaction/TransactionLevel.java

@@ -58,7 +58,7 @@ public enum TransactionLevel {
 	SERIALIZABLE(Connection.TRANSACTION_SERIALIZABLE);
 
 	/** 事务级别，对应Connection中的常量值 */
-	private int level;
+	private final int level;
 
 	TransactionLevel(int level) {
 		this.level = level;

hutool-db/src/test/java/cn/hutool/db/CRUDTest.java

@@ -22,7 +22,7 @@ import java.util.List;
  */
 public class CRUDTest {
 
-	private static Db db = Db.use("test");
+	private static final Db db = Db.use("test");
 
 	@Test
 	public void findIsNullTest() throws SQLException {

hutool-db/src/test/java/cn/hutool/db/ConcurentTest.java

@@ -1,16 +1,15 @@
 package cn.hutool.db;
 
-import java.sql.SQLException;
-import java.util.List;
-
-import org.junit.Before;
-import org.junit.Ignore;
-import org.junit.Test;
-
 import cn.hutool.core.collection.CollectionUtil;
 import cn.hutool.core.lang.Console;
 import cn.hutool.core.thread.ThreadUtil;
 import cn.hutool.db.handler.EntityListHandler;
+import org.junit.Before;
+import org.junit.Ignore;
+import org.junit.Test;
+
+import java.sql.SQLException;
+import java.util.List;
 
 /**
  * SqlRunner线程安全测试
@@ -31,17 +30,14 @@ public class ConcurentTest {
 	@Test
 	public void findTest() {
 		for(int i = 0; i < 10000; i++) {
-			ThreadUtil.execute(new Runnable() {
-				@Override
-				public void run() {
-					List<Entity> find;
-					try {
-						find = db.find(CollectionUtil.newArrayList("name AS name2"), Entity.create("user"), new EntityListHandler());
-					} catch (SQLException e) {
-						throw new DbRuntimeException(e);
-					}
-					Console.log(find);
+			ThreadUtil.execute(() -> {
+				List<Entity> find;
+				try {
+					find = db.find(CollectionUtil.newArrayList("name AS name2"), Entity.create("user"), new EntityListHandler());
+				} catch (SQLException e) {
+					throw new DbRuntimeException(e);
 				}
+				Console.log(find);
 			});
 		}
 		

hutool-db/src/test/java/cn/hutool/db/SessionTest.java

@@ -1,11 +1,9 @@
 package cn.hutool.db;
 
-import java.sql.SQLException;
-
 import org.junit.Ignore;
 import org.junit.Test;
 
-import cn.hutool.core.lang.func.VoidFunc1;
+import java.sql.SQLException;
 
 /**
  * 事务性数据库操作单元测试
@@ -30,11 +28,6 @@ public class SessionTest {
 	@Test
 	@Ignore
 	public void txTest() throws SQLException {
-		Session.create("test").tx(new VoidFunc1<Session>() {
-			@Override
-			public void call(Session session) throws SQLException {
-				session.update(Entity.create().set("age", 78), Entity.create("user").set("name", "unitTestUser"));
-			}
-		});
+		Session.create("test").tx(session -> session.update(Entity.create().set("age", 78), Entity.create("user").set("name", "unitTestUser")));
 	}
 }