1 public final class DbConn
 2 {
 3     public static  Connection getconn()
 4     {
 5         Connection conn = null;
 6
 7         String driver = "com.mysql.cj.jdbc.Driver";
 8         String user   = "root";
 9         String passwd = "root";
10         String url = "jdbc:mysql://localhost:3306/store?useSSL=false&serverTimezone=UTC";//指定要访问的数据库store
11
12         //已加载完驱动
13         try
14         {
15             Class.forName(driver);
16             conn = DriverManager.getConnection(url,user,passwd);
17         }catch (SQLException e)
18         {
19             e.printStackTrace();
20         }
21         catch (ClassNotFoundException e)
22         {
23             e.printStackTrace();
24         }
25         return conn;
26     }
27
28 }

 1 public final class DbClose
 2 {
 3     /**
 4      * 关闭 添加功能 资源
 5      * @param pstmt,rs,conn
 6      */
 7         public static void addClose(PreparedStatement pstmt, Connection conn)
 8         {
 9             /*
10              * 多个 try-catch 出发点：安全
11              */
12             try
13             {
14                 if (pstmt != null)
15                 {
16                     pstmt.close();
17                 }
18             } catch (SQLException e1)
19             {
20                 e1.printStackTrace();
21             }
22             try
23             {
24                 if (conn != null)
25                 {
26                     conn.close();
27                 }
28             } catch (SQLException e)
29             {
30                 e.printStackTrace();
31             }
32         }
33
34         /**
35          * 关闭资源
36          * @param pstmt,rs,conn
37          */
38         public static void queryClose(PreparedStatement pstmt, ResultSet rs, Connection conn)
39         {
40             try
41             {
42                 if (pstmt != null)
43                 {
44                     pstmt.close();
45                 }
46             } catch (SQLException e1)
47             {
48                 e1.printStackTrace();
49             }
50             try
51             {
52                 if (rs != null )
53                 {
54                     rs.close();
55                 }
56             } catch (SQLException e1)
57             {
58                 e1.printStackTrace();
59             }
60             try
61             {
62                 if (conn != null)
63                 {
64                     conn.close();
65                 }
66             } catch (SQLException e)
67             {
68                 e.printStackTrace();
69             }
70         }
71
72 }

 1 public class Show {
 2
 3     public static void main(String[] args) {
 4         //声明Connection对象
 5         Connection con;
 6         //驱动程序名
 7         String driver = "com.mysql.cj.jdbc.Driver";
 8         //URL指向要访问的数据库名mydata
 9         String url = "jdbc:mysql://localhost:3306/store?useSSL=false&serverTimezone=UTC";
10         //MySQL配置时的用户名
11         String user = "root";
12         //MySQL配置时的密码
13         String password = "root";
14         //遍历查询结果集
15         try {
16             //加载驱动程序
17             Class.forName(driver);
18             //1.getConnection()方法，连接MySQL数据库！！
19             con = DriverManager.getConnection(url,user,password);
20             if(!con.isClosed())
21                 System.out.println("Succeeded connecting to the Database!");
22             //2.创建statement类对象，用来执行SQL语句！！
23             Statement statement = con.createStatement();
24             //要执行的SQL语句
25             String sql = "select * from goods where Gid='g231'";
26             //3.ResultSet类，用来存放获取的结果集！！
27             ResultSet rs = statement.executeQuery(sql);
28             System.out.println("-----------------");
29             System.out.println("执行结果如下所示:");
30             System.out.println("-----------------");
31             System.out.println("名称" + "\t" + "数量");
32             System.out.println("-----------------");
33
34             String Gname = null;
35             String Gnum = null;
36             while(rs.next()){
37                 //获取stuname这列数据
38                 Gname = rs.getString("Gname");
39                 //获取stuid这列数据
40                 Gnum = rs.getString("Gnum");
41
42                 //输出结果
43                 System.out.println(Gname + "\t" + Gnum);
44             }
45             rs.close();
46             con.close();
47         } catch(ClassNotFoundException e) {
48             //数据库驱动类异常处理
49             System.out.println("Sorry,can`t find the Driver!");
50             e.printStackTrace();
51             } catch(SQLException e) {
52             //数据库连接失败异常处理
53             e.printStackTrace();
54             }catch (Exception e) {
55             // TODO: handle exception
56             e.printStackTrace();
57         }finally{
58             System.out.println("数据库数据成功获取！！");
59         }
60     }
61
62 }