数据库连接工具将结果集封装成map或List<Map>

public final class DBUtil {

private final static String driverName = "com.mysql.jdbc.Driver";    //驱动
private final static String url = "jdbc:mysql://localhost:3306/testtwo";
private final static String userName = "root";
private final static String pwd = "123456";

public static Connection getMysqlConnection()
{
Connection connection = null;
try{
Class.forName(driverName);
connection = DriverManager.getConnection(url,userName,pwd);
}
catch (Exception e)
{
e.printStackTrace();
}
return connection;
}
}

public class BaseDao {

/**
* 获取list结果集
* @param sql
* @return
*/
public static List<Map<String, Object>> findListBySql(String sql) {
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
Connection connection = null;
Statement st = null;
ResultSet rs = null;
try
{
connection = DBUtil.getMysqlConnection();
st = connection.createStatement();
rs = st.executeQuery(sql);
ResultSetMetaData md = rs.getMetaData();
int columnCount = md.getColumnCount();
while (rs.next()) {
Map<String, Object> rowData = new HashMap<String, Object>();
for (int i = 1; i <= columnCount; i++) {
rowData.put(md.getColumnName(i), rs.getObject(i));
}
list.add(rowData);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
closeResources(rs,st,connection);
}
return list;
}

/**
* 获取map结果集
* @param sql
* @return
*/
public static Map<String, Object> findMapBySql(String sql) {
Map<String, Object> map = new HashMap<>();
Connection connection = null;
Statement st = null;
ResultSet rs = null;
try {
connection = DBUtil.getMysqlConnection();
st = connection.createStatement();
rs = st.executeQuery(sql);
ResultSetMetaData md = rs.getMetaData();
int columnCount = md.getColumnCount();
while (rs.next()) {
for (int i = 1; i <= columnCount; i++) {
map.put(md.getColumnName(i), rs.getObject(i));
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
closeResources(rs,st,connection);
}
return map;
}

public static void closeResources(ResultSet rs,Statement st,Connection connection)
{
try
{
if (rs != null)
{
rs.close();
}
if (st != null)
{
st.close();
}
if (connection != null)
{
connection.close();
}
}
catch (SQLException e)
{
e.printStackTrace();
}
}

public static void main(String[] args) {
List<Map<String,Object>> list = BaseDao.findListBySql("select * from user   ");
System.out.println(list.get(0).get("name"));
}
}