Java学习笔记40（sql：将数据库内数据存入对象中）

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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);
}
}
}