JDBC查询数据后对数据进行封装

1. 实体类代码

package user;

public class user {
        private int uid ;
        private int age;
        private String name;

    public user() {

    }
    
    public int getUid() {
        return uid;
    }

    public void setUid(int uid) {
        this.uid = uid;
    }

    public int getAge() {
        return age;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "user{" +
                "uid=" + uid +
                ", age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

    public user(int uid, int age, String name) {
        this.uid = uid;
        this.age = age;
        this.name = name;
    }
}

2.数据库链接

package jdbc;

import java.sql.*;

public class TestJdbc {
    public static Connection getConnnetion() throws ClassNotFoundException, SQLException {
        //声明驱动
        Class.forName("com.mysql.jdbc.Driver");

        //声明连接信息
        String url ="jdbc:mysql://localhost:3306/student?useSSL=true&characterEncoding=utf-8&serverTimezone=GMT";
        String username = "root";
        String password = "*****";
        Connection connection = DriverManager.getConnection(url,username,password);
        
        return connection;
        
    }
    //释放资源
    public static void relase(Connection connection, Statement statement, ResultSet resultSet) throws SQLException {
        if (resultSet!=null){
            resultSet.close();
        }
        if (connection!=null){
            connection.close();
        }
        if (statement!=null){
            statement.close();
        }


    }


}

3.操作类

package jdbc;

import org.junit.Test;
import user.user;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class TestJdbc_02 {

    @Test
    public void test() throws SQLException, ClassNotFoundException {
        Connection connnetion = TestJdbc.getConnnetion();
        //sql语句
        String sql ="select * from user";
        //预编译对象
        PreparedStatement preparedStatement = connnetion.prepareStatement(sql);
        ResultSet resultSet = preparedStatement.executeQuery();

        List<user> uesr1 = new ArrayList<user>();

        //处理结果集
        while (resultSet.next()){
        user u = new user();
        u.setAge(resultSet.getInt("age"));
        u.setName(resultSet.getString("name"));
        u.setUid(resultSet.getInt("uid"));
        
        uesr1.add(u);

        }
        for (user u1:uesr1){
            System.out.println(u1);
        }

        TestJdbc.relase(connnetion,preparedStatement,resultSet);

    }
}

4.运行结果

数据库数据：

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `age` int NULL DEFAULT NULL,
  `uid` int NOT NULL,
  PRIMARY KEY (`uid`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('lin', 1, 1);
INSERT INTO `user` VALUES ('jia', 2, 3);
INSERT INTO `user` VALUES ('zeng', 3, 4);

SET FOREIGN_KEY_CHECKS = 1;

备注：
Mysql 5.0版本和 Mysql 8.0版本的驱动是不一样的：
Mysql 5.0的版本驱动为： Class.forName(“com.mysql.jdbc.Driver”);
Mysql 8.0的版本驱动为： Class.forName(“com.mysql.cj.jdbc.Driver”);

同时在url中要加入useSSL=true&characterEncoding=utf-8&serverTimezone=GMT编码类型和时间地区