java 连接mysql增删改查

Posted 2020-10-07 博客园站长

 

1、创建mysql测试表 

 

2、按下图创建3个文件夹与3个类

 

3、三个类的代码

PersionDao ：目录(Data Access Object), 数据访问对象是第一个面向对象的数据库接口 

 1 package com.test.dao;
 2 
 3 import com.test.entity.Person;
 4 
 5 import java.sql.DriverManager;
 6 import java.sql.PreparedStatement;
 7 import java.sql.ResultSet;
 8 import java.sql.SQLException;
 9 
10 /**
11  * Created by wdw on 2017/9/7.
12  */
13 public class PersonDao {
14 
15     private final static String DRIVER = "com.mysql.jdbc.Driver";
16     private final static String URL = "jdbc:mysql://localhost:3306/wdw";
17     private final static String USERNAME = "root";
18     private final static String PASSWORD = "123456";
19 
20     /**
21      * 添加一个人
22      *
23      * @param person
24      * @return boolean
25      */
26     public boolean insert(Person person) {
27         boolean flag = false;//
28         try {
29             Class.forName(DRIVER);//加载数据库驱动
30             java.sql.Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
31 //            使用jar包中的connection接口，并通过DriveManager类的静态方法getConnection()创建连接对象conn
32             String sql = "INSERT INTO sys_users(id,name,code) VALUES(?,?,?)";//编写sql语句
33             PreparedStatement ps = conn.prepareStatement(sql);////创建预处理对象ps
34             ps.setInt(1, person.getId());
35             ps.setString(2, person.getName());
36             ps.setString(3, person.getCode());
37 
38             if (ps.executeUpdate() > 0) {
39                 flag = true;
40             }
41             System.out.print(flag);
42             ps.close();
43             conn.close();
44 
45         } catch (ClassNotFoundException e) {
46 
47             e.printStackTrace();
48         } catch (SQLException e) {
49             e.printStackTrace();
50         }
51         return flag;
52     }
53 
54     /**
55      * 添加一个人
56      *
57      * @param id
58      * @return boolean
59      */
60     public Person selectById(String id) {
61         Person p = new Person();
62         try {
63             Class.forName(DRIVER);//加载数据库驱动
64             java.sql.Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
65             String sql = "delete sys_users where id=" + id;//编写sql语句
66             PreparedStatement ps = conn.prepareStatement(sql);////创建预处理对象ps
67             ResultSet r = ps.executeQuery();
68             while (r.next()) {
69                 p.setId(r.getInt("id"));
70                 p.setName((r.getString("code")));
71                 p.setCode(r.getString("name"));
72             }
73 
74             ps.close();
75             conn.close();
76 
77         } catch (ClassNotFoundException e) {
78 
79             e.printStackTrace();
80         } catch (SQLException e) {
81             e.printStackTrace();
82         }
83         return p;
84     }
85 
86 }

View Code

entity：entity目录(实体)，实体就是一个特定的软件模块。

 1 package com.test.entity;
 2 
 3 /**
 4  * Created by wdw on 2017/9/7.
 5  */
 6 public class Person {
 7 
 8     private int id;
 9     private String code;
10     private String name;
11 
12     public int getId() {
13         return id;
14     }
15 
16     public void setId(int id) {
17         this.id = id;
18     }
19 
20     public String getCode(){
21         return  this.code;
22 
23     }
24     public  void  setCode(String code)
25     {
26         this.code=code;
27 
28     }
29     public String getName(){
30         return  this.name;
31 
32     }
33     public  void  setName(String name)
34     {
35         this.name=name;
36 
37     }
38 }

View Code

test：test目录，最终的试行测试。

 1 package com.test.test;
 2 
 3 import com.test.dao.PersonDao;
 4 import com.test.entity.Person;
 5 
 6 /**
 7  * Created by wdw on 2017/9/7.
 8  */
 9 public class test {
10     public static void main(String[] args) {
11         Person ps = new Person();
12         ps.setId(1);
13         ps.setCode("编号");
14         ps.setName("张三");
15         PersonDao s = new PersonDao();
16         boolean aResult = s.insert(ps);  //add a use
17         boolean uResult = s.insert(ps);  //delete a use
18         boolean dResult = s.insert(ps);  //delete a use
19     }
20 
21 }

View Code

 

4、运行测试，记得在main断点。