MyBatis学习笔记_2-CRUD&动态SQL

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luer9 2023-03-02 05:49:10 博主文章分类：JAVA WEB ©著作权

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Mybatis

文章目录

Mybatis

基本结构
CRUD_代理dao

基本结构

MyBatis学习笔记_2-CRUD&动态SQL_List

CRUD_代理dao

UserDao.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.yll.dao.UserDao">
    <!--查询所有-->
    <select id="findAll" resultType="com.yll.domain.User">
        select * from user;
    </select>
    <!--保存用户-->
    <insert id="saveUser" parameterType="com.yll.domain.User">
        <!--配置插入操作后，获取插入数据的id-->
        <selectKey keyProperty="id" keyColumn="id" order="AFTER" resultType="java.lang.Integer">
            select last_insert_id();
        </selectKey>

        insert into user(username, address, sex, birthday)values(#{username}, #{address}, #{sex}, #{birthday});
    </insert>

    <!--更新用户    parameterType 说明带参-->
    <update id="updateUser" parameterType="com.yll.domain.User">
        update user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday} where id = #{id};
    </update>

    <!--根据id删除用户-->
    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id = #{uid}; <!--这个占位符可以随便写-->
    </delete>

    <!--根据id查询用户-->
    <select id="findById" parameterType="java.lang.Integer" resultType="com.yll.domain.User">
        select * from user where id = #{uid}; <!--占位符没有名称限制-->
    </select>

    <!--根据名称模糊查询-->
    <select id="findByName" parameterType="java.lang.String" resultType="com.yll.domain.User">
        select * from user where username like #{username};
    </select>

    <!--获取用户的总记录条数-->
    <select id="findTotal" resultType="java.lang.Integer">
        select count(*) from user;
    </select>

    <!--根据QueryVo的条件查询用户-->
    <select id="findUserByVo" parameterType="com.yll.domain.QueryVo" resultType="com.yll.domain.User">
        select * from user where username like #{user.username};
    </select>

    <select id="findUserByCondition" parameterType="com.yll.domain.User" resultType="com.yll.domain.User">
--         select * from user where 1 = 1
        select * from user
        <where>
            <if test="username != null">
                and username like #{username}
            </if>
            <if test="sex != null">
                and sex = '女'
            </if>
        </where>
    </select>

    <!--抽取重复的sql语句-->
    <sql id="defaultUser">
        select * from user
    </sql>
    <!--根据queryvo中的id集合实现查询用户列表-->
    <select id="findUserInids" parameterType="com.yll.domain.QueryVo" resultType="com.yll.domain.User">
        <include refid="defaultUser" />
        <where>
            <if test="ids != null">
                <foreach collection="ids" open="and id in (" close=")" item="uid" separator=",">
                    #{uid}
                </foreach>
            </if>

        </where>
    </select>
</mapper>

SqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--mybaits的主配置文件-->
<configuration>
    <!-- 配置环境 -->
    <environments default="mysql">
        <!--配置mysql环境-->
        <environment id="mysql">
            <!--配置事务的类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源（连接池）-->
            <dataSource type="POOLED">
                <!--配置连接数据库的4个基本信息-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/db_mybatis?useUnicode=true&characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="52151"/>
            </dataSource>
        </environment>
    </environments>
    <!--指定映射配置文件的位置，映射配置文件指的是每个dao独立的配置文件
    如果使用注解来配置的话，此处应该使用class属性指定被注解的dao全限定类名
    -->
    <mappers>
        <mapper resource="com/yll/dao/UserDao.xml"/>
<!--        <mapper class="com.yll.dao.UserDao"/>-->
    </mappers>
</configuration>

UserDao 接口

package com.yll.dao;

import com.yll.domain.QueryVo;
import com.yll.domain.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/**
 * 用户的持久层接口
 * */
public interface UserDao {
    /**
     * 查询所有
     * */
//    @Select("select * from user")
    List<User> findAll();
    /**
     * 保存用户
     * */

    void saveUser(User user);

    /**
     * 更新用户
     * */
    void updateUser(User user);

    /**
     * 根据id删除用户
     * */
    void deleteUser(Integer id);

    /**
     * 根据id查询用户信息
     * */
    User findById(Integer id);

    /**
     * 根据用户姓名模糊查询用户信息
     * */
    List<User> findByName(String name);

    /**
     * 查询总用户数
     * */
    int findTotal();

    /**
     * 使用实体类中的条件查询用户
     * */
    List<User> findUserByVo(QueryVo vo);


    /**
     * 根据条件查询
     * */
    List<User> findUserByCondition(User user);

    /**
     * 根据queryvo中提供的id集合，查询用户信息
     * */
    List<User> findUserInids(QueryVo vo);
}

domain->QueryVo

package com.yll.domain;

import java.util.List;

public class QueryVo {
    private User user;
    private List<Integer> ids;

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public List<Integer> getIds() {
        return ids;
    }

    public void setIds(List<Integer> ids) {
        this.ids = ids;
    }
}

domain->User

package com.yll.domain;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {
    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

测试类

package com.yll.test;

import com.sun.javaws.IconUtil;
import com.yll.dao.UserDao;
import com.yll.domain.QueryVo;
import com.yll.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import javax.annotation.Resource;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class MyBatisTest {
    /**
     * 入门案例
     * */
//    public static void main(String[] args) throws IOException {
//        //1.读取配置文件
//        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//        //2.创建SqlSessionFactory工厂
//        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
//        SqlSessionFactory factory = builder.build(in);
//        //3.使用工厂生产SqlSession对象
//        SqlSession session = factory.openSession();
//        //4.使用SqlSesssion创建Dao接口的代理对象
//        UserDao userDao = session.getMapper(UserDao.class);
//        //5.使用代理对象执行方法
//        List<User> users = userDao.findAll();
//        for(User user: users) {
//            System.out.println(user);
//        }
//        //6.释放资源
//        session.close();
//        in.close();
//    }
    private InputStream in;
    private SqlSession sqlSession;
    private UserDao userDao;
    @Before
    public void init() throws IOException {
        //1.读取配置文件，生成字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.获取SqlsessionFactory对象
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        //3.获取SqlSession对象
        sqlSession = factory.openSession();
        //4.获取dao的代理对象
        userDao = sqlSession.getMapper(UserDao.class);
    }
    @After
    public void destory() throws IOException {
        //提交事务
        sqlSession.commit();
        //6.释放资源
        sqlSession.close();
        in.close();
    }

    /**
     * 测试查询所有
     * */
    @Test
    public void testFindAll() throws IOException {


        //5.执行查询所有方法
        List<User> users = userDao.findAll();
        for(User user : users) {
            System.out.println(user);
        }

    }
    /**
     * 测试保存操作
     * */
    @Test
    public void testSave(){
        User user = new User();
        user.setUsername("mybatis新插入的");
        user.setAddress("河南");
        user.setSex("男");
        user.setBirthday(new Date());
        System.out.println("before ::: "+user);
        //5.执行查询所有方法
        userDao.saveUser(user);
        System.out.println("after ::: "+user);
    }
    /**
     * 测试更新操作
     * */
    @Test
    public void testUpdate(){
        User user = new User();
        user.setId(1003);
        user.setUsername("newname");
        user.setAddress("河南");
        user.setSex("女");
        user.setBirthday(new Date());
        System.out.println(user);
        userDao.updateUser(user);
    }

    /**
     * 测试删除操作
     * */
    @Test
    public void testDelete(){
        userDao.deleteUser(1009);
    }

    /**
     * 测试查询一个用户信息的操作
     * */
    @Test
    public void testFindById(){
        User user = userDao.findById(1001);
        System.out.println(user);
    }

    /**
     * 测试模糊查询
     * */
    @Test
    public void testFindByName(){
        List<User> users = userDao.findByName("%s%");
        for(User user : users) {
            System.out.println(user);
        }
    }

    /**
     * 测试查询总记录条数
     * */
    @Test
    public void testFindTotal(){
        int total = userDao.findTotal();
        System.out.println(total);
    }

    /**
     * 测试实体类作为查询条件的操作
     * */
    @Test
    public void testFindByVo(){
        QueryVo vo= new QueryVo();
        User user = new User();
        user.setUsername("%ss%");  //模糊查询的效果
        vo.setUser(user);
        List<User> users = userDao.findUserByVo(vo);
        for(User u:users){
            System.out.println(u);
        }
    }

    /**
     * 测试查询条件
     * */
    @Test
    public void testFindByCondition(){
        User user = new User();
        user.setUsername("%ss%");  //模糊查询的效果
        List<User> users = userDao.findUserByCondition(user);
        for(User u:users){
            System.out.println(u);
        }
    }
    /**
     * 测试foreach标签使用
     * */
    @Test
    public void testFindInids(){
        QueryVo vo = new QueryVo();
        List<Integer> list = new ArrayList<Integer>();
        list.add(1001); list.add(1002); list.add(1003); list.add(1004);
        vo.setIds(list);
        List<User> users = userDao.findUserInids(vo);
        for (User user:users) {
            System.out.println(user);
        }
    }
}