Java JDBC 数据库链接小结随笔

 1 package demo1;
 2 
 3 import java.sql.*;
 4 
 5 public class demo1 {
 6     public static void main(String[] args) {
 7         try {
 8             Class.forName("com.mysql.cj.jdbc.Driver");
 9             String url="jdbc:mysql://127.0.0.1:3306/jdbc?serverTimezone=UTC";
10             /*目前手动改变 sql 服务器 时区报错问题*/
11             String username="root";
12             String password="root";
13             /*  com.mysql.cj.jdbc.Driver   */
14 
15             Connection con= DriverManager.getConnection(url,username,password);
16             System.out.println(con);
17             Statement stmt = con.createStatement();
18             ResultSet rs = stmt.executeQuery("select * from test");
19             while (rs.next()){
20                 int id=rs.getInt("id");
21                 String name=rs.getString(2);
22                 System.out.println("id:"+id+"-"+"name:"+name);
23             }
24 
25         }
26         catch (ClassNotFoundException e){
27             e.printStackTrace();
28         }
29         catch (SQLException e){
30             e.printStackTrace();
31         }
32     }
33 }

 1 package demo1;
 2 
 3 import Util.connectionUtil;
 4 
 5 import java.sql.*;
 6 
 7 public class TestDemo {
 8     /*
 9     * 1. prepareStatement   Statement 区别
10     *
11     *   1)prepareStatement继承自 statement
12     *           prepareStatement{  execute、 executeQuery 和 executeUpdate 已被更改以使之不再需要参数}
13 
14     * 2.   接口用法
15 
16     * */
17 
18     public static void main(String[] args) {
19 
20         //直接使用 Util 包下自定义的 链接数据库方法
21             Connection con=connectionUtil.getConnections("jdbc");
22             Statement stmt=null;
23             PreparedStatement ps=null;
24 
25             ResultSet resultSet=null;
26             ResultSet rs=null;
27 
28             String selectSql="select * from test";
29             try {
30                 stmt=con.createStatement();
31                 resultSet=stmt.executeQuery(selectSql);
32 
33 
34             System.out.println("Statement 接口：");
35             while (resultSet.next()){
36                 int id=resultSet.getInt("id");
37                 String name=resultSet.getString("name");
38                 System.out.println("id:"+id+"---"+"name:"+name);
39             }
40 
41 
42             System.out.println("PrepareStatement 接口：");
43 
44 
45             /* PrepareStatement */
46             ps=con.prepareStatement(selectSql);
47             rs=ps.executeQuery();
48             while (rs.next()){
49                 int id=rs.getInt("id");
50                 String name=rs.getString("name");
51                 System.out.println("id:"+id+"---"+"name:"+name);
52             }
53 
54 
55         } catch (SQLException e) {
56             e.printStackTrace();
57         }
58         finally {
59             if(con!=null){
60                 try {
61                     con.close();
62                 } catch (SQLException e) {
63                     e.printStackTrace();
64                 }
65             }
66         }
67     }
68 }