Java学习笔记40（sql：将数据库内数据存入对象中）

新建一个数据表：

use  qy97;
create table student(
  id int primary key auto_increment,
  sname varchar(50),
  gander varchar(50),
  age int,
  score int
);
insert into student values
(1,'张三','男',18,20),
(2,'小红','女',17,97),
(3,'小明','男',22,100),
(4,'小强','男',16,80),
(5,'小花','女',20,99);

然后我们用Java代码来读取该数据库的所有信息，并将每一条信息都放进一个学生对象中，首先需要建一个学生类，类名与表名一致，并且类中的属性也要与表中的属性一致，实现get和set方法，要注意数据类型，代码如下：

package com.zs.Demo;

public class Student {
    private int id;
    private String sname;
    private String gander;
    private int age;
    private int score;

    public Student(){
        super();
    }

    public Student(int id, String sname, String gander, int age, int score) {
        this.id = id;
        this.sname = sname;
        this.gander = gander;
        this.age = age;
        this.score = score;
    }

    public int getId() {
        return id;
    }

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

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public String getGander() {
        return gander;
    }

    public void setGander(String gander) {
        this.gander = gander;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getScore() {
        return score;
    }
//    重写tostring 方法方便查看
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", sname='" + sname + '\'' +
                ", gander='" + gander + '\'' +
                ", age=" + age +
                ", score=" + score +
                '}';
    }

    public void setScore(int score) {
        this.score = score;
    }

}

然后链接数据库查询所有数据，并将数据存入对象中，将对象存入集合中，调用之前写的JDBCUtils工具类：

package com.zs.Demo;

import JDBCUtils.JDBCUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

public class Demo3 {
    public static void main(String[] args) {
        try {
            getStudent();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private static void getStudent() throws SQLException {
        Connection conn = JDBCUtils.getConnection();
        String sql="select * from student;";
        PreparedStatement pre = conn.prepareStatement(sql);
        //执行sql语句，得到结果集
        ResultSet rs = pre.executeQuery();
//        创建集合存储对象
        ArrayList<Student> stuArr = new ArrayList<>();
        while (rs.next()) {
            Student s = new Student();
//            设置对象的变量值
            s.setId(rs.getInt("id"));
            s.setSname(rs.getString("sname"));
            s.setGander(rs.getString("gander"));
            s.setAge(rs.getInt("age"));
            s.setScore(rs.getInt("score"));
//            将对象添加至集合
            stuArr.add(s);
        }
        for (Student student : stuArr) {
            System.out.println(student);
        }
    }
}

运行结果：