使用 JDBC 连接 MySQL 数据库并进行数据查询操作

 1 import java.sql.*;
 2 
 3 /**
 4  * 使用JDBC查询mysql数据库示例
 5  */
 6 public class Main {
 7 
 8     public static void main(String[] args) {
 9 
10         try {
11             // 1.反射获取mysql驱动实例
12             Class.forName("com.mysql.jdbc.Driver");
13         } catch (ClassNotFoundException e) {
14             System.out.println("找不到驱动程序类，加载驱动失败！");
15             e.printStackTrace();
16         }
17 
18         String url = "jdbc:mysql://localhost:3306/cjl_demo";
19         String username = "username";
20         String password = "password";
21         try {
22             // 2.驱动实例->Connection
23             Connection conn = DriverManager.getConnection(url, username, password);
24 
25             // 3.Connection->Statement
26             Statement stmt = conn.createStatement();
27 
28             // 4.Statement->ResultSet
29             String sql = "select * from stu";
30             ResultSet rs = stmt.executeQuery(sql);
31 
32             // 5.通过ResultSet获取数据
33             while (rs.next()) {
34                 String id = rs.getString("id");
35                 String name = rs.getString("name");
36                 String score = rs.getString("score");
37                 String sex = rs.getString("sex");
38                 String theClass = rs.getString("class");
39                 System.out.println(id + "--" + name + "--" + score + "--" + sex + "--" + theClass);
40                 /**
41                  * 1--a--66--男--1
42                  * 2--b--82--女--2
43                  * 3--c--77--男--1
44                  * 4--d--90--女--2
45                  * 5--e--90--女--1
46                  */
47             }
48 
49             // 6.依次关闭ResultSet,Statement,Connection
50             if (rs != null) {
51                 try {
52                     rs.close();
53                 } catch (SQLException e) {
54                     System.out.println("ResultSet关闭时出现错误！");
55                     e.printStackTrace();
56                 }
57             }
58             if (stmt != null) {
59                 try {
60                     stmt.close();
61                 } catch (SQLException e) {
62                     System.out.println("Statement关闭时出现错误！");
63                     e.printStackTrace();
64                 }
65             }
66             if (conn != null) {
67                 try {
68                     conn.close();
69                 } catch (SQLException e) {
70                     System.out.println("Connection关闭时出现错误！");
71                     e.printStackTrace();
72                 }
73             }
74 
75         } catch (SQLException e) {
76             System.out.println("数据库连接失败！");
77             e.printStackTrace();
78         }
79     }
80 }