數(shù)據(jù)庫(kù)中的表

目錄結(jié)構(gòu)

目錄結(jié)構(gòu)2

目錄結(jié)構(gòu)3

用戶的實(shí)體類(lèi)、跟數(shù)據(jù)庫(kù)表對(duì)應(yīng)起來(lái)。

package com.haila.domain;/*
 * @program: maven_javaweb
 *
 * @Date: 2020/3/17 0017 16:34
 *
 * @Author : haira
 *
 * @Description:MavenUser的實(shí)體類(lèi)
 */

public class MavenUser {
    private String name;
    private int age;
    private String gender;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

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

要實(shí)現(xiàn)的接口（查詢?nèi)浚?/p>

package com.haila.dao;/*
 * @program: maven_javaweb
 *
 * @Date: 2020/3/17 0017 16:40
 *
 * @Author : haira
 *
 * @Description:
 */

import com.haila.domain.MavenUser;

import java.util.List;

public interface MavenUserDao {
    public List<MavenUser> findAll();
}

接口實(shí)現(xiàn)類(lèi)、跟數(shù)據(jù)庫(kù)交互把想要的數(shù)據(jù)取回來(lái)

package com.haila.dao.impl;/*
 * @program: maven_javaweb
 *
 * @Date: 2020/3/17 0017 16:41
 *
 * @Author : haira
 *
 * @Description:
 */

import com.haila.dao.MavenUserDao;
import com.haila.domain.MavenUser;

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

public class MavenDaoImpl implements MavenUserDao {
    @Override
    public List<MavenUser> findAll() {
        List<MavenUser> list = new ArrayList<MavenUser>();
        //先獲取contection對(duì)象
        Connection connection = null;
        //獲取真正操作數(shù)據(jù)的對(duì)象
        PreparedStatement pst = null;
        //執(zhí)行數(shù)據(jù)庫(kù)查詢操作
        ResultSet rs = null;
        try {
            //加載驅(qū)動(dòng)類(lèi)
            Class.forName("com.mysql.cj.jdbc.Driver");
            //先獲取contection對(duì)象
            connection = DriverManager.getConnection("jdbc:mysql:///haila?useSSL=false&serverTimezone=UTC","root", "7281412");
            //獲取真正操作數(shù)據(jù)的對(duì)象
            pst = connection.prepareCall("select * from maven_user");
            //執(zhí)行數(shù)據(jù)庫(kù)查詢操作
            rs = pst.executeQuery();
            //把數(shù)據(jù)庫(kù)結(jié)果集轉(zhuǎn)成java的List集合

            while (rs.next()){
                MavenUser items = new MavenUser();
                items.setName(rs.getNString("name"));
                items.setAge(rs.getInt("age"));
                items.setGender(rs.getNString("gender"));
                list.add(items);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                pst.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        return list;
    }
}

測(cè)試方法，實(shí)現(xiàn)控制臺(tái)輸出

package com.haila.test;/*
 * @program: maven_javaweb
 *
 * @Date: 2020/3/17 0017 17:09
 *
 * @Author : haira
 *
 * @Description:
 */

import com.haila.dao.MavenUserDao;
import com.haila.dao.impl.MavenDaoImpl;
import com.haila.domain.MavenUser;
import org.junit.Test;

import java.util.List;

public class MavenUserTest {
    @Test
    public void findAll(){
        MavenUserDao mavenUserDao=new MavenDaoImpl();
        List<MavenUser> list=mavenUserDao.findAll();
        for (MavenUser mavenUser:list) {
            System.out.println(mavenUser);
        }
    }

}

運(yùn)行結(jié)果:

yunxingjieguo

總結(jié)：
1.數(shù)據(jù)庫(kù)連接有兩個(gè)地方要注意一下會(huì)涉及到版本問(wèn)題。
2.數(shù)據(jù)庫(kù)四個(gè)屬性：數(shù)據(jù)庫(kù)驅(qū)動(dòng)、數(shù)據(jù)庫(kù)地址、數(shù)據(jù)庫(kù)用戶名、密碼。

數(shù)據(jù)庫(kù)連接