JDBC释放数据库连接

try(){}写法会自动关闭连接

String sql = "select password from user where name = ?";
try(Connection c = getConnection(); PreparedStatement ps = c.prepareStatement(sql);){
    ps.setString(1, userName);
    ResultSet rs = ps.executeQuery();
    if(rs.next())
        return rs.getString("password");
} catch (SQLException e) {
    e.printStackTrace();
}