add query method

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

@@ -5,6 +5,7 @@ import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.Collection;
 import java.util.List;
+import java.util.Map;
 
 import javax.sql.DataSource;
 
@@ -154,6 +155,27 @@ public abstract class AbstractDb implements Serializable {
 		}
 	}
 
+	/**
+	 * 支持占位符的查询，例如：select * from table where field1=:name1
+	 *
+	 * @param <T>    结果集需要处理的对象类型
+	 * @param sql    查询语句，使用参数名占位符，例如:name
+	 * @param rsh    结果集处理对象
+	 * @param paramMap 参数
+	 * @return 结果对象
+	 * @throws SQLException SQL执行异常
+	 * @since 5.1.1
+	 */
+	public <T> T query(String sql, RsHandler<T> rsh, Map<String, Object> paramMap) throws SQLException {
+		Connection conn = null;
+		try {
+			conn = this.getConnection();
+			return SqlExecutor.query(conn, sql, rsh, paramMap);
+		} finally {
+			this.closeConnection(conn);
+		}
+	}
+
 	/**
 	 * 执行非查询语句<br>
 	 * 语句包括 插入、更新、删除

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

@@ -55,7 +55,6 @@ public class DialectFactory {
 	public final static String DRIVER_DM7 = "dm.jdbc.driver.DmDriver";
 	
 	private static Map<DataSource, Dialect> dialectPool = new ConcurrentHashMap<>();
-	private static final Object lock = new Object();
 
 	private DialectFactory() {
 	}
@@ -153,7 +152,9 @@ public class DialectFactory {
 	public static Dialect getDialect(DataSource ds) {
 		Dialect dialect = dialectPool.get(ds);
 		if(null == dialect) {
-			synchronized (lock) {
+			// 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);
 				if(null == dialect) {
 					dialect = newDialect(ds);

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

@@ -220,7 +220,7 @@ public class SqlExecutor {
 	}
 
 	/**
-	 * 执行查询语句<br>
+	 * 执行查询语句，例如：select * from table where field1=:name1 <br>
 	 * 此方法不会关闭Connection
 	 * 
 	 * @param <T> 处理结果类型