添加依赖
这个可以参考上节：《springboot极简教程014-数据库之MyBatis》，再贴一下吧：
<!--MyBatis-->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<!-- mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.21</version>
</dependency>
示例
下面是一个实体操作类：
@Mapper
public interface PersonMapper {
@Insert("insert into person (id, name, age, job) values (#{id}, #{name}, #{age}, #{job})")
void add(Person person);
@Delete("delete from person where id = #{id}")
void delete(@Param("id") int id);
@Update("update person set name = #{name} where id = #{id}")
void update(@Param("id") int id, @Param("name") String name);
@Select("select * from person where name = #{name}")
Person queryByName(@Param("name") String name);
@Select("select * from person")
List<Person> queryAll();
}
使用：
@Autowired
private PersonMapper personMapper;
@Test
public void testAdd(){
Person person = new Person(13, "RRR", "会计", 22);
personMapper.add(person);
}
@Test
public void testDelete(){
personMapper.delete(12);
}
@Test
public void testUpdate(){
personMapper.update(13, "TTT");
}
@Test
public void testQuery(){
Person person = personMapper.queryByName("TTT");
System.out.println(person);
}
@Test
public void testQueryAll(){
List<Person> persons = personMapper.queryAll();
persons.stream().forEach((p) -> System.out.println(p));
}
就这么简单？对！就这么简单！
但是在实际项目中，对于实体操作类的常用函数接口，会考虑封装到一个Mapper基类里去，这样就提高了复用性。具体做法就是封装一个通用Mapper，例如：CommonMapper：
package com.example.dao;
import tk.mybatis.mapper.common.Mapper;
import tk.mybatis.mapper.common.MySqlMapper;
import java.util.List;
import java.util.Map;
// 注意: 该接口不能被扫描到，否则会出错
public interface CommonMapper<T> extends Mapper<T>, MySqlMapper<T> {
List<T> queryList(Map<String, Object> map);
}
其他的实体操作类就可以继承CommonMapper：
package com.example.dao.mapper;
import com.example.dao.CommonMapper;
import com.example.dao.model.Course;
import com.example.util.StringUtil;
import org.apache.ibatis.annotations.*;
import org.springframework.stereotype.Component;
import java.util.List;
import java.util.Map;
/**
* Component注解不添加也没没关系，不加的话service在引入LearnMapper会有错误提示，但不影响
* SpringBoot使用Mybatis注解进行一对多和多对多查询 https://blog.csdn.net/KingBoyWorld/article/details/78966789
*/
@Component
@Mapper
public interface CourseMapper extends CommonMapper<Course> {
String getAuthorName(Long id);
@Insert("insert into course(author, title,url) values(#{author},#{title},#{url})")
int insert(Course course);
@Update("update course set author=#{author},title=#{title},url=#{url} where id = #{id}")
int update(Course course);
@DeleteProvider(type = CourseSqlBuilder.class, method = "deleteByids")
int deleteByIds(@Param("ids") String[] ids);
@Select("select * from course where id = #{id}")
@Results(id = "learnMap", value = {
@Result(column = "id", property = "id", javaType = Long.class),
@Result(property = "author", column = "author", javaType = Long.class),
@Result(property = "title", column = "title", javaType = String.class),
@Result(property = "user", column = "author",
one = @One(select = "com.example.dao.mapper.UserMapper.findUserById"))
})
Course selectByKey(@Param("id") Long id);
@SelectProvider(type = CourseSqlBuilder.class, method = "queryCourseByParams")
@Results({
@Result(column = "id", property = "id", javaType = Long.class),
@Result(property = "author_id", column = "author", javaType = Long.class),
@Result(property = "title", column = "title", javaType = String.class),
@Result(property = "author", column = "author",
one = @One(select = "com.example.dao.mapper.UserMapper.findUserNickyById"))
})
List<Course> queryList(Map<String, Object> params);
class CourseSqlBuilder {
public String queryCourseByParams(final Map<String, Object> params) {
StringBuffer sql = new StringBuffer();
sql.append("select * from course where 1=1");
if (!StringUtil.isNull((String) params.get("author"))) {
sql.append(" and author like '%").append((String) params.get("author")).append("%'");
}
if (!StringUtil.isNull((String) params.get("title"))) {
sql.append(" and title like '%").append((String) params.get("title")).append("%'");
}
System.out.println("查询sql==" + sql.toString());
return sql.toString();
}
//删除的方法
public String deleteByids(@Param("ids") final String[] ids) {
StringBuffer sql = new StringBuffer();
sql.append("DELETE FROM course WHERE id in(");
for (int i = 0; i < ids.length; i++) {
if (i == ids.length - 1) {
sql.append(ids[i]);
} else {
sql.append(ids[i]).append(",");
}
}
sql.append(")");
return sql.toString();
}
}
}
注意
接口不能被扫描到的话可以在Application中添加注解@MapperScan：
@MapperScan(basePackages = "com.example.dao", markerInterface = CommonMapper.class)
不要使用org.mybatis.spring.annotation.MapperScan，而是：
import tk.mybatis.spring.annotation.MapperScan;