MyBatis Plus与spring boot 的使用

浅浅的花香味﹌ 2024-04-03 08:15 44阅读 0赞

*  新建一个spring boot项目
 *  导入相关依赖,spring boot 2.2.1

<dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>mybatis-plus-boot-starter</artifactId>
                <version>3.3.1</version>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>

*  配置

# 应用名称
    spring:
      application:
        name: mybatisPlusApplication
      datasource:
        url: jdbc:mysql://localhost:3306/mybatis_plus?characterEncoding=utf-8&serverTimezone=UTC
        username: root
        password: root
        driver-class-name: com.mysql.cj.jdbc.Driver
    mybatis-plus:
      mapper-locations: classpath*:/mapper/**/*.xml
      #mybatis日志
      configuration:
        log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
      global-config:
        db-config:
          logic-delete-value: 1  #逻辑删除 注意：被删除前，数据的deleted 字段的值必须是 0，才能被选取出来执行逻辑删除的操作
          logic-not-delete-value: 0

*  新建配置类MybatisPlusConfig

package com.wang.config;
    
    
    import com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor;
    import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    @MapperScan("com.wang.mapper")
    public class MybatisPlusConfig {
        /**
         * 乐观锁插件
         */
        @Bean
        public OptimisticLockerInterceptor optimisticLockerInterceptor() {
            return new OptimisticLockerInterceptor();
        }
    
        /**
         * 分页插件
         */
        @Bean
        public PaginationInterceptor paginationInterceptor() {
            return new PaginationInterceptor();
        }
    
    
    
    }

*  实体类User

package com.wang.entity;
    
    
    import com.baomidou.mybatisplus.annotation.FieldFill;
    import com.baomidou.mybatisplus.annotation.TableField;
    import com.baomidou.mybatisplus.annotation.TableLogic;
    import com.baomidou.mybatisplus.annotation.Version;
    import lombok.Data;
    import org.springframework.stereotype.Component;
    import java.util.Date;
    @Component
    @Data
    public class User {
        private  Long id;
        private String name;
        private  Integer age;
        private String email;
        @TableField(fill = FieldFill.INSERT)
        private Date createTime;  //create_time
        @TableField(fill = FieldFill.INSERT_UPDATE)
        private Date updateTime; //update_time
        @Version
        @TableField(fill = FieldFill.INSERT_UPDATE)
        private Integer version;
        @TableLogic
        private Integer deleted;
    
    }

*  mapper

package com.wang.mapper;
    
    import com.baomidou.mybatisplus.core.mapper.BaseMapper;
    import com.wang.entity.User;
    import org.springframework.stereotype.Repository;
    
    @Repository
    public interface UserMapper extends BaseMapper<User> {
    }

自动填充MyMetaObjectHandler类

package com.wang.entity;
    
    import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
    import org.apache.ibatis.reflection.MetaObject;
    import org.springframework.stereotype.Component;
    
    import java.util.Date;
    @Component
    public class MyMetaObjectHandler implements MetaObjectHandler {
        //mp执行添加操作，这个方法执行
        @Override
        public void insertFill(MetaObject metaObject) {
            this.setFieldValByName("createTime",new Date(),metaObject);
            this.setFieldValByName("updateTime",new Date(),metaObject);
            this.setFieldValByName("version",1,metaObject);
    
        }
    
        //mp执行修改操作，这个方法执行
        @Override
        public void updateFill(MetaObject metaObject) {
            this.setFieldValByName("updateTime",new Date(),metaObject);
            this.setFieldValByName("version",1,metaObject);
        }
    }

*  测试类

package com.wang;
    
    
    import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
    import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    import com.wang.entity.User;
    import com.wang.mapper.UserMapper;
    import org.junit.jupiter.api.Test;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.test.context.SpringBootTest;
    
    import java.util.Arrays;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    
    @SpringBootTest
    class MyBatisPlusApplicationTests {
    
        @Autowired
        private UserMapper userMapper;
    
    
    
        @Test
        public void findUsers(){
            List<User> users = userMapper.selectList(null);
            System.out.println(users);
        }
        //修改操作,通过id更新
        @Test
        public void TestUpdate(){
            User user = new User();
            user.setId(1L);
            user.setName("lucymary");
            int count = userMapper.updateById(user);
            System.out.println(count);
        }
        @Test
        public void testAdd(){
            User user = new User();
            user.setName("张三");
            user.setAge(20);
            user.setEmail("lucymary@gmail.com");
            int insert = userMapper.insert(user);
            System.out.println(insert);
        }
    
        @Test
        public void testDelete(){
            User user = new User();
            user.setId(1L);
            int count = userMapper.deleteById(user.getId());
            System.out.println(count);
        }
        //测试乐观锁
        @Test
        public void OptimisticLocker(){
            //查询
            User user = new User();
            user.setId(1576148994537553922L);
            User user1 = userMapper.selectById(user.getId());
            //修改
            user1.setName("测试");
            int i = userMapper.updateById(user1);
            System.out.println(i);
        }
    
        //多个id批量查询selectBatchIds
        @Test
        public void testSelectByIds(){
            List<User> userList = userMapper.selectBatchIds(Arrays.asList(2, 3, 4, 5));
            System.out.println(userList);
        }
    
        //简单条件查询
        @Test
        public void testSelectByMap(){
            HashMap<String, Object> hashMap = new HashMap<>();
            hashMap.put("name", "test");
            hashMap.put("age", 20);
            List<User> selectByMap = userMapper.selectByMap(hashMap);
            System.out.println(selectByMap);
    
        }
    
    
        //分页查询
        @Test
        public void testPagination(){
            Page page = new Page(1, 3);
            Page selectPage = userMapper.selectPage(page, null);
            //得到所有的分页数据
            long pages = selectPage.getPages();//总页数
            long current= selectPage.getCurrent();//当前页
            List<User> list = selectPage.getRecords();//查询数据集合
            long total = selectPage.getTotal();//总数据条数
            boolean hasNext = selectPage.hasNext();//下1页
            boolean hasPrevious = selectPage.hasPrevious();//上一页
    
            System.out.println(pages);
            System.out.println(current);
            System.out.println(list);
            System.out.println(hasNext);
            System.out.println(hasPrevious);
    
        }
    
        //根据id删除记录
        @Test
        public void testDeleteById(){
            int byId = userMapper.deleteById(3L);
            System.out.println(byId);
        }
        //根据id删除记录批量
        @Test
        public void  testDeleteByIds(){
            List<User> ids = userMapper.selectBatchIds(Arrays.asList(2, 3));
            System.out.println(ids);
        }
        //简单的条件删除
        @Test
        public void testDeleteByMap(){
            HashMap<String, Object> map = new HashMap<>();
            map.put("name","1136");
            map.put("age",20);
            int byMap = userMapper.deleteByMap(map);
            System.out.println(byMap);
        }
    
        //测试逻辑删除后的查询
        //MyBatis Plus中查询操作也会自动添加逻辑删除字段的判断
        @Test
        public  void testDeleteSelect(){
            List<User> userList = userMapper.selectList(null);
            userList.forEach(System.out::println);
        }
    
        //条件操作
        @Test
        public void testQuery(){
            QueryWrapper<User> query = new QueryWrapper<>();
            query.isNull("name")
                    .ge("age",20)
                    .isNotNull("email");
            List<User> userList = userMapper.selectList(query);
            userList.forEach(System.out::println);
        }
    
        @Test
        public void testSelectOne(){
            QueryWrapper<User> queryWrapper=new QueryWrapper<>();
            queryWrapper.eq("name", "Sandy");
            User user = userMapper.selectOne(queryWrapper);//只能返回一条记录
            System.out.println(user);
        }
    
        @Test
        public void testSelectCount(){
            QueryWrapper<User> queryWrapper= new QueryWrapper<>();
            queryWrapper.between("age",20,35);
            Integer count= userMapper.selectCount(queryWrapper);
            System.out.println(count);
        }
    
        @Test
        public void testSelectMaps(){
            QueryWrapper<User> queryWrapper= new QueryWrapper<>();
            queryWrapper.select("name","age")
                    .like("name","S")
                    .likeRight("email","t");
            java.util.List<Map<String, Object>> user= userMapper.selectMaps(queryWrapper);//返回值是map列表
            user.forEach(System.out::println);
        }
        @Test
        public void testSelectListOrderBy(){
            QueryWrapper<User> queryWrapper= new QueryWrapper<>();
            queryWrapper.orderByAsc("age");
          List<User> userList=  userMapper.selectList(queryWrapper);
          userList.forEach(System.out::println);
        }
    
    }