MyBatisPlus的增删改查SpringBoot方式

1、POM文件添加引用

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>MyBatisBoot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>MyBatisBoot</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2、配置文件(application.yml)

mybatis-plus:
  #  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml
  type-aliases-package: com.yas.entity
  configuration:
    lazy-loading-enabled: true
    aggressive-lazy-loading: false
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    map-underscore-to-camel-case: false
    cache-enabled: false

  global-config:
    db-config:
      id-type: auto

3、配置类(解决分页问题)

 1 package com.yas.config;
 2 
 3 import com.baomidou.mybatisplus.annotation.DbType;
 4 import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
 5 import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
 6 import org.mybatis.spring.annotation.MapperScan;
 7 import org.springframework.context.annotation.Bean;
 8 import org.springframework.context.annotation.Configuration;
 9 
10 @Configuration
11 @MapperScan("com.yas.dao")
12 public class MybatisPlusConfig {
13 
14     //配置mp分页插件
15     @Bean
16     public MybatisPlusInterceptor mybatisPlusInterceptor() {
17         MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
18         interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
19         return interceptor;
20     }
21 }

4、实体类(POJO)

 1 package com.yas.entity;
 2 
 3 import com.baomidou.mybatisplus.annotation.IdType;
 4 import com.baomidou.mybatisplus.annotation.TableField;
 5 import com.baomidou.mybatisplus.annotation.TableId;
 6 import lombok.AllArgsConstructor;
 7 import lombok.Data;
 8 import lombok.NoArgsConstructor;
 9 import lombok.ToString;
10 
11 import java.util.Date;
12 
13 @Data
14 @NoArgsConstructor
15 @AllArgsConstructor
16 @ToString
17 public class SysUser {
18     //指定主键生成方式为数据库自增
19     @TableId(type= IdType.AUTO)
20     private Integer id;
21     private String account;
22     private String username;
23 
24     //查询时不反悔该字段的值
25     @TableField(select = false)
26     private String pwd;
27 
28     private Date gmt_create;
29 
30     //假如属性名与数据库表中的列名不同，可以在这里设置列名
31     @TableField(value = "gmt_modified")
32     private Date gmt_modified;
33 
34     //这个属性不会进行映射
35     @TableField(exist = false)
36     private String otherProperty;
37 }

5、测试方法：

  1 package com.yas;
  2 
  3 import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
  4 import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
  5 import com.baomidou.mybatisplus.core.metadata.IPage;
  6 import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
  7 import com.yas.dao.SysUserPlusDAO;
  8 import com.yas.entity.SysStaff;
  9 import com.yas.entity.SysUser;
 10 import org.junit.jupiter.api.Test;
 11 import org.springframework.beans.factory.annotation.Autowired;
 12 import org.springframework.boot.test.context.SpringBootTest;
 13 
 14 import java.sql.Timestamp;
 15 import java.util.*;
 16 
 17 @SpringBootTest
 18 public class MyBatisPlusTests {
 19     @Autowired
 20     SysUserPlusDAO sysUserPlusDAO;
 21 
 22     //插入
 23     @Test
 24     void testInsert() {
 25         SysUser user = new SysUser(null, "manager", "王羲之", "000000", new Date(), new Date(), null);
 26         int result = sysUserPlusDAO.insert(user);
 27         System.out.println(result);
 28         System.out.println("主键回填：" + user.getId());
 29     }
 30 
 31     //根据id查询
 32     @Test
 33     void testSelectById() {
 34         SysUser sysUser = sysUserPlusDAO.selectById(8);
 35         System.out.println(sysUser);
 36     }
 37 
 38     //根据id更新
 39     @Test
 40     void testUpdateById() {
 41         SysUser user = new SysUser();
 42         user.setId(8);
 43         user.setUsername("王献之");
 44         int result = sysUserPlusDAO.updateById(user);
 45         System.out.println(result);
 46     }
 47 
 48     //根据条件更新
 49     @Test
 50     void testUpdate() {
 51         SysUser user = new SysUser();
 52         user.setPwd("888888");
 53 
 54         QueryWrapper<SysUser> wrapper = new QueryWrapper<>();
 55         wrapper.eq("account", "manager");
 56         int result = sysUserPlusDAO.update(user, wrapper);
 57         System.out.println(result);
 58     }
 59 
 60 
 61     //根据条件更新2
 62     @Test
 63     void testUpdate2() {
 64         UpdateWrapper<SysUser> wrapper = new UpdateWrapper<>();
 65         wrapper.set("pwd", "666666").eq("account", "manager");
 66         int result = sysUserPlusDAO.update(null, wrapper);
 67         System.out.println(result);
 68     }
 69 
 70     //根据条件删除
 71     @Test
 72     void testDeleteById() {
 73         int result = sysUserPlusDAO.deleteById(8);
 74         System.out.println(result);
 75     }
 76 
 77     //根据map条件删除，多条件之间是and关系
 78     @Test
 79     void testDeleteByMap() {
 80         Map<String, Object> map = new HashMap<>();
 81         map.put("username", "王维");
 82         map.put("pwd", "666666");
 83         //根据map删除，多条件之间是 and 关系
 84         int result = sysUserPlusDAO.deleteByMap(map);
 85         System.out.println(result);
 86     }
 87 
 88     //使用条件删除
 89     @Test
 90     void testDeleteByWrapper() {
 91         //用法一：
 92 //        QueryWrapper<SysUser> wrapper = new QueryWrapper<>();
 93 //        wrapper.eq("username","杜甫").eq("pwd","666666");
 94 
 95         //用法二：(推荐)
 96         SysUser user = new SysUser();
 97         user.setUsername("李白");
 98         user.setPwd("666666");
 99         QueryWrapper<SysUser> wrapper = new QueryWrapper<>(user);
100 
101         int result = sysUserPlusDAO.delete(wrapper);
102         System.out.println(result);
103     }
104 
105     //根据id批量删除数据
106     @Test
107     void testDeleteByBatchIds() {
108         int result = sysUserPlusDAO.deleteBatchIds(Arrays.asList(9, 10));
109         System.out.println(result);
110     }
111 
112     //查询 条件in
113     @Test
114     void testSelectBatchIds() {
115         List<SysUser> users = sysUserPlusDAO.selectBatchIds(Arrays.asList(1, 2, 3, 4, 5));
116         for (SysUser user : users) {
117             System.out.println(user);
118         }
119     }
120 
121     //查询单条，返回结果最多只能有1条
122     @Test
123     void testSelectOne() {
124         SysUser user = new SysUser();
125         user.setId(1);
126         user.setAccount("admin");
127         user.setUsername("管理员");
128         QueryWrapper<SysUser> wrapper = new QueryWrapper<>(user);
129 
130         SysUser user2 = sysUserPlusDAO.selectOne(wrapper);
131         System.out.println(user2);
132     }
133 
134     @Test
135     void testSelectCount() {
136         QueryWrapper<SysUser> wrapper = new QueryWrapper<>();
137         wrapper.isNotNull("username");
138         int result = sysUserPlusDAO.selectCount(wrapper);
139         System.out.println(result);
140     }
141 
142     @Test
143     void testSelectList() {
144         QueryWrapper<SysUser> wrapper = new QueryWrapper<>();
145         wrapper.isNotNull("username");
146         List<SysUser> users = sysUserPlusDAO.selectList(wrapper);
147         for (SysUser user : users) {
148             System.out.println(user);
149         }
150     }
151 
152     @Test
153     void testSelectPage() {
154         Page<SysUser> page = new Page<>(1, 1);
155 
156         QueryWrapper<SysUser> wrapper = new QueryWrapper<>();
157         wrapper.like("username", "C");
158         IPage<SysUser> iPage = sysUserPlusDAO.selectPage(page, wrapper);
159         System.out.println("数据总条数：" + iPage.getTotal());
160         System.out.println("总页数：" + iPage.getPages());
161         System.out.println("当前是第" + iPage.getCurrent() + "页");
162 
163         List<SysUser> records = iPage.getRecords();
164         for (SysUser record : records) {
165             System.out.println(record);
166         }
167     }
168 
169     @Test
170     void testAllEq(){
171         Map<String,Object> map = new HashMap<>();
172         map.put("id",1);
173         map.put("account","admin");
174         map.put("username","管理员");
175 
176         QueryWrapper<SysUser> wrapper = new QueryWrapper<>();
177 //        wrapper.allEq(map);//is null 可以作为条件
178 //        wrapper.allEq(map,false);//is null 不会作为条件
179         wrapper.allEq((k,v)->(k.equals("age") || k.equals("id")),map);//指定条件
180         List<SysUser> users = sysUserPlusDAO.selectList(wrapper);
181         for (SysUser user : users) {
182             System.out.println(user);
183         }
184     }
185 }

对于一些比较简单的SQL语句，可以直接用MybatisPlus提供的方法。

对于复杂的SQL语句，还是用Mybaits直接编写SQL语句更加易于编写和维护。

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原文地址：https://www.cnblogs.com/asenyang/p/15476286.html