Mybatis学习（实现增删改查）

首先在项目java下创建mapper文件，在resources下创建好mapper映射文件，还要在pojo下创建其相应的实体类：
在这里插入图片描述

其中BrandMapper文件:

package com.itheima.mapper;


import com.itheima.pojo.Brand;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Select;

import java.util.List;
import java.util.Map;

public interface BrandMapper {


    /**
     * 查询所有
     */
    List<Brand> selectAll();


    /**
     * 查看详情：根据Id查询
     */
    Brand selectById(int id);

    /**
     * 条件查询
     *  * 参数接收
     *      1. 散装参数：如果方法中有多个参数，需要使用@Param("SQL参数占位符名称")
     *      2. 对象参数:对象的属性名称要和参数占位符名称一致
     *      3. map集合参数
     *
     */

    //List selectByCondition(@Param("status") int status, @Param("companyName") String companyName, @Param("brandName") String brandName);


    //List selectByCondition(Brand brand);
    List<Brand> selectByCondition(Map map);

    /**
     * 单条件动态查询
     * @param brand
     * @return
     */
    List<Brand> selectByConditionSingle(Brand brand);


    /**
     * 添加
     */
    void add(Brand brand);


    /**
     * 修改
     */
    int update(Brand brand);

    /**
     * 根据id删除
     */
    void deleteById(int id);


    /**
     * 批量删除
     */
    void deleteByIds(int[] ids);

}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72

BrandMapper.xml文件：

<?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">

<!--
    namespace:名称空间
-->

<mapper namespace="com.itheima.mapper.BrandMapper">

    <!--
        数据库表的字段名称  和  实体类的属性名称 不一样，则不能自动封装数据
            * 起别名：对不一样的列名起别名，让别名和实体类的属性名一样
                * 缺点：每次查询都要定义一次别名
                    * sql片段
                        * 缺点：不灵活
            * resultMap：
                1. 定义<resultMap>标签
                2. 在<select>标签中，使用resultMap属性替换 resultType属性

    -->
    <!--
        id：唯一标识
        type：映射的类型，支持别名
    -->
    <resultMap id="brandResultMap" type="brand">
        <!--
            id：完成主键字段的映射
                column：表的列名
                property：实体类的属性名
            result：完成一般字段的映射
                column：表的列名
                property：实体类的属性名
        -->
        <result column="brand_name" property="brandName"/>
        <result column="company_name" property="companyName"/>
    </resultMap>



    <select id="selectAll" resultMap="brandResultMap">
        select *
        from tb_brand;
    </select>


    <!--
        sql片段
    -->
    <!--
    <sql id="brand_column">
         id, brand_name as brandName, company_name as companyName, ordered, description, status
     </sql>

     <select id="selectAll" resultType="brand">
         select
             <include refid="brand_column" />
         from tb_brand;
     </select>
     -->
    <!--<select id="selectAll" resultType="brand">
        select *
        from tb_brand;
    </select>-->


    <!--
        * 参数占位符：
            1. #{}:会将其替换为 ?，为了防止SQL注入
            2. ${}：拼sql。会存在SQL注入问题
            3. 使用时机：
                * 参数传递的时候：#{}
                * 表名或者列名不固定的情况下：${} 会存在SQL注入问题

         * 参数类型：parameterType：可以省略
         * 特殊字符处理：
            1. 转义字符：
            2. CDATA区:CD+提示
    -->
   <!-- <select id="selectById"  resultMap="brandResultMap">
        select *
        from tb_brand where id = #{id};

    </select>
    -->
    <select id="selectById" resultMap="brandResultMap">
        select *
        from tb_brand
        where id
         <![CDATA[
            <
         ]]>
         #{id};

    </select>

    <!--
        条件查询
    -->
    <!-- <select id="selectByCondition" resultMap="brandResultMap">
         select *
         from tb_brand
         where status = #{status}
           and company_name like #{companyName}
           and brand_name like #{brandName}
     </select>-->


    <!--
        动态条件查询
            * if: 条件判断
                * test：逻辑表达式
            * 问题：
                * 恒等式
                * <where> 替换 where 关键字
    -->
    <select id="selectByCondition" resultMap="brandResultMap">
        select *
        from tb_brand
        /* where 1 = 1*/
        <where>

            <if test="status != null">
                and status = #{status}
            </if>
            <if test="companyName != null and companyName != '' ">
                and company_name like #{companyName}
            </if>
            <if test="brandName != null and brandName != '' ">
                and brand_name like #{brandName}
            </if>
        </where>

    </select>
    <!--<select id="selectByConditionSingle" resultMap="brandResultMap">
        select *
        from tb_brand
        where
        <choose>&lt;!&ndash;相当于switch&ndash;&gt;
            <when test="status != null">&lt;!&ndash;相当于case&ndash;&gt;
                status = #{status}
            </when>
            <when test="companyName != null and companyName != '' ">&lt;!&ndash;相当于case&ndash;&gt;
                company_name like #{companyName}
            </when>
            <when test="brandName != null and brandName != ''">&lt;!&ndash;相当于case&ndash;&gt;
                brand_name like #{brandName}
            </when>
            <otherwise>
                1 = 1
            </otherwise>

        </choose>

    </select>-->

    <select id="selectByConditionSingle" resultMap="brandResultMap">
        select *
        from tb_brand
        <where>
            <choose><!--相当于switch-->
                <when test="status != null"><!--相当于case-->
                    status = #{status}
                </when>
                <when test="companyName != null and companyName != '' "><!--相当于case-->
                    company_name like #{companyName}
                </when>
                <when test="brandName != null and brandName != ''"><!--相当于case-->
                    brand_name like #{brandName}
                </when>

            </choose>
        </where>
    </select>

<!--添加的主键返回-->
    <insert id="add" useGeneratedKeys="true" keyProperty="id">
        insert into tb_brand (brand_name, company_name, ordered, description, status)
        values (#{brandName}, #{companyName}, #{ordered}, #{description}, #{status});

    </insert>

    <update id="update">
        update tb_brand
        <set>
            <if test="brandName != null and brandName != ''">
                brand_name = #{brandName},
            </if>
            <if test="companyName != null and companyName != ''">
                company_name = #{companyName},
            </if>
            <if test="ordered != null">
                ordered = #{ordered},
            </if>
            <if test="description != null and description != ''">
                description = #{description},
            </if>
            <if test="status != null">
                status = #{status}
            </if>
        </set>
        where id = #{id};
    </update>


    <delete id="deleteById">
        delete from tb_brand where id = #{id};
    </delete>
    <!--
        mybatis会将数组参数，封装为一个Map集合。
            * 默认：array = 数组
            * 使用@Param注解改变map集合的默认key的名称
    -->

    <delete id="deleteByIds">
        delete from tb_brand where id
        in
            <foreach collection="array" item="id" separator="," open="(" close=")">
                #{id}
            </foreach>
             ;
    </delete>

</mapper>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225

然后添加其相应的测试类：

package com.itheima.test;

import com.itheima.mapper.BrandMapper;
import com.itheima.pojo.Brand;
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.Test;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MyBatisTest {


    @Test
    public void testSelectAll() throws IOException {
        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法
        List<Brand> brands = brandMapper.selectAll();
        System.out.println(brands);

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testSelectById() throws IOException {
        //接收参数
        int id = 1;

        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法
        Brand brand = brandMapper.selectById(id);
        System.out.println(brand);

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testSelectByCondition() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "华为";
        String brandName = "华为";

        // 处理参数
        companyName = "%" + companyName + "%";
        brandName = "%" + brandName + "%";

        //封装对象
       /* Brand brand = new Brand();
        brand.setStatus(status);
        brand.setCompanyName(companyName);
        brand.setBrandName(brandName);*/

        Map map = new HashMap();
        // map.put("status" , status);
        map.put("companyName", companyName);
        // map.put("brandName" , brandName);

        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法

        //List brands = brandMapper.selectByCondition(status, companyName, brandName);
//        List brands = brandMapper.selectByCondition(brand);
        List<Brand> brands = brandMapper.selectByCondition(map);
        System.out.println(brands);

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testSelectByConditionSingle() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "华为";
        String brandName = "华为";

        // 处理参数
        companyName = "%" + companyName + "%";
        brandName = "%" + brandName + "%";

        //封装对象
        Brand brand = new Brand();
        //brand.setStatus(status);
        brand.setCompanyName(companyName);
        //brand.setBrandName(brandName);

        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法

        //List brands = brandMapper.selectByCondition(status, companyName, brandName);
//        List brands = brandMapper.selectByCondition(brand);

        List<Brand> brands = brandMapper.selectByConditionSingle(brand);
        System.out.println(brands);

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testAdd() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "波导手机";
        String brandName = "波导";
        String description = "手机中的战斗机";
        int ordered = 100;


        //封装对象
        Brand brand = new Brand();
        brand.setStatus(status);
        brand.setCompanyName(companyName);
        brand.setBrandName(brandName);
        brand.setDescription(description);
        brand.setOrdered(ordered);

        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法

        brandMapper.add(brand);

        //提交事务
        sqlSession.commit();

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testAdd2() throws IOException {
        //接收参数
        int status = 1;
        String companyName = "波导手机";
        String brandName = "波导";
        String description = "手机中的战斗机";
        int ordered = 100;


        //封装对象
        Brand brand = new Brand();
        brand.setStatus(status);
        brand.setCompanyName(companyName);
        brand.setBrandName(brandName);
        brand.setDescription(description);
        brand.setOrdered(ordered);

        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法

        brandMapper.add(brand);
        Integer id = brand.getId();
        System.out.println(id);

        //提交事务
        sqlSession.commit();

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testUpdate() throws IOException {
        //接收参数
        int status = 0;
        String companyName = "波导手机";
        String brandName = "波导";
        String description = "波导手机,手机中的战斗机";
        int ordered = 200;
        int id = 6;


        //封装对象
        Brand brand = new Brand();
        brand.setStatus(status);
//        brand.setCompanyName(companyName);
//        brand.setBrandName(brandName);
//        brand.setDescription(description);
//        brand.setOrdered(ordered);
        brand.setId(id);

        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法


        int count = brandMapper.update(brand);
        System.out.println(count);
        //提交事务
        sqlSession.commit();

        //5. 释放资源
        sqlSession.close();

    }





    @Test
    public void testDeleteById() throws IOException {
        //接收参数

        int id = 6;


        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法

        brandMapper.deleteById(id);

        //提交事务
        sqlSession.commit();

        //5. 释放资源
        sqlSession.close();

    }


    @Test
    public void testDeleteByIds() throws IOException {
        //接收参数

        int[] ids = {5,7,8};


        //1. 获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //SqlSession sqlSession = sqlSessionFactory.openSession(true);

        //3. 获取Mapper接口的代理对象
        BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);

        //4. 执行方法

        brandMapper.deleteByIds(ids);

        //提交事务
        sqlSession.commit();

        //5. 释放资源
        sqlSession.close();

    }


}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361

相关阅读:
若依和芋道
 由浅入深详解四种分布式锁
 贴片加工炉温度曲线测试方法简介
 Vue ＜script setup＞
Nacos/Sentinel/Linked2技术总结待续
 教你六步拆解 DDD领域驱动设计落地实践
 YOLOV:图像对象检测器在视频对象检测方面表现也很不错
 配置tomcat可用的代理访问ArcGIS Enterprise/GeoScene Enterprise加密服务
 AI学习指南机器学习篇-随机森林原理
 入侵防御系统（IPS）网络安全设备介绍
原文地址：https://blog.csdn.net/weixin_52326703/article/details/127990008