自定义JDBC工具类

左手的ㄟ右手 2023-08-17 16:09 105阅读 0赞

因为数据库的连接代码都是固定的，为了将减少重复的代码的书写，可以将这些代码封装为一个工具类，获取数据库的连接对象。

1 import java.sql.Connection;
     2 import java.sql.DriverManager;
     3 import java.sql.ResultSet;
     4 import java.sql.SQLException;
     5 import java.sql.Statement;
     6 
     7 public final class JDBCUtils {
        // 不能被继承或重写
     8     private JDBCUtils() {
     9     }
    10 
    11     private static Connection con;
    12 
    13     static {
    14         try {
    15             Class.forName("com.mysql.jdbc.Driver");
    16             String url = "jdbc:mysql://localhost:3306/student mangement system";
    17             String username = "root";
    18             String password = "root";
    19             con = DriverManager.getConnection(url, username, password);
    20         } catch (Exception e) {
    21             e.printStackTrace();
    22             throw new RuntimeException(e + "数据库连接失败");
    23         }
    24     }
    25 
    26     public static Connection getConnection() {
    27         return con;
    28     }
    29 
    30     public static void close(Connection con, Statement stat) {
    31 
    32         if (stat != null) {
    33             try {
    34                 stat.close();
    35             } catch (SQLException e) {
    36                 e.printStackTrace();
    37                 System.out.println("stat流关闭异常！");
    38             }
    39         }
    40 
    41         if (con != null) {
    42             try {
    43                 con.close();
    44             } catch (SQLException e) {
    45                 e.printStackTrace();
    46                 System.out.println("con流关闭异常！");
    47             }
    48         }
    49 
    50     }
    51 
    52     public static void close(Connection con, Statement stat, ResultSet rs) {
    53         if (rs != null) {
    54             try {
    55                 rs.close();
    56             } catch (SQLException e) {
    57                 e.printStackTrace();
    58                 System.out.println("rs流关闭异常！");
    59             }
    60         }
    61 
    62         if (stat != null) {
    63             try {
    64                 stat.close();
    65             } catch (SQLException e) {
    66                 e.printStackTrace();
    67                 System.out.println("stat流关闭异常！");
    68             }
    69         }
    70 
    71         if (con != null) {
    72             try {
    73                 con.close();
    74             } catch (SQLException e) {
    75                 e.printStackTrace();
    76                 System.out.println("con流关闭异常！");
    77             }
    78         }
    79 
    80     }
    81 }

测试工具类：

import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    public class Test {
        public static void main(String[] args)throws Exception {
            Connection con = JDBCUtils.getConnection();
            PreparedStatement pst = con.prepareStatement("SELECT sname,studentno FROM student");
            ResultSet rs = pst.executeQuery();
            while(rs.next()){
                System.out.println(rs.getString("sname")+"   "+rs.getString("studentno"));
            }
            JDBCUtils.close(con, pst, rs);
        }
    }

![1392562-20190819152538929-809586776.png][]

转载于:https://www.cnblogs.com/zhai1997/p/11377377.html

[1392562-20190819152538929-809586776.png]: /images/20230810/5b5501d4f0ef4131a92a7b194dcad766.png