maven的java工程取mysql数据库数据

maven的java工程取mysql数据库数据

创建User实体类：

 

public class User {
    private int id;
    private String NAME;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", NAME='" + NAME + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getNAME() {
        return NAME;
    }

    public void setNAME(String NAME) {
        this.NAME = NAME;
    }
}

 

在pom.xml中配置mysql驱动jar包

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.29</version>
    </dependency>

 UserDao接口：

public interface UserDao {
    public List<User> findAll();
}

UserDaoImpl实现类：

public class UserDaoImpl implements UserDao {
    @Override
    public List<User> findAll(){
        List<User> list = null;
        Connection connection = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        try {
            //加载驱动类
            Class.forName("com.mysql.cj.jdbc.Driver");
            //获取connection对象
            connection = DriverManager.getConnection("jdbc:mysql:///day23","root","root");
            //获取真正操作数据的对象
            pst = connection.prepareCall("select * from province");
            //执行数据库查询操作
            rs = pst.executeQuery();
            //把数据库结果集转成java的List集合
            list = new ArrayList<>();
            while (rs.next()){
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setNAME(rs.getString("NAME"));
                list.add(user);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                connection.close();
                pst.close();
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }

        return list;
    }
}

UserTest测试：

public class UserTest {

    @Test
    public void findAll(){
        UserDao user = new UserDaoImpl();
        List<User> list = user.findAll();
        for (User user1 : list) {
            System.out.println(user1);
        }
    }
}