Mybatis的级联查询，分步查询，一对一，一对多和多对一
配置和代码目录
***log4j配置 --可以打印入日志，也可以使用系统自带的STDOUT_LOGGING个人喜欢log4j
***jdbc.properties的大概配置
3、studentMapper.java、banjiMapper.java
***util配置
package com.xiaomin.util;
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 java.io.IOException;
import java.io.InputStream;
public class mybatisUtil {
private static String path="mybatis-config.xml";
private static SqlSessionFactory sqlSessionFactory;
private static InputStream inputStream;;
static {
try {
inputStream = Resources.getResourceAsStream(path);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSqlSession(){
SqlSession sqlSession = sqlSessionFactory.openSession();
return sqlSession;
}
}
***log4j配置 --可以打印入日志，也可以使用系统自带的STDOUT_LOGGING个人喜欢log4j
#????DEBUG????????console?file???????console?file?????????
log4j.rootLogger=DEBUG, console, file
#??????????
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.Target=System.out
log4j.appender.console.Threshold=DEBUG
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%c]-%m%n
#?????????
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=./log/xiaomin.log
log4j.appender.file.MaxFileSize=100KB
log4j.appender.file.Threshold=DEBUG
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[%p][%d{yy-MM-dd}][%c]-%m%n
#??????
log4j.logger.org.mybatis=DEBUG
log4j.logger.java.sql=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.preparedStatement=DEBUG
***mybatis-config.xml的配置
<?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">
<configuration>
<properties resource="jdbc.properties"></properties>
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>
<!--取别名，偷懒可用-->
<typeAliases>
<typeAlias type="com.xiaomin.pojo.student" alias="student"/>
<typeAlias type="com.xiaomin.pojo.banji" alias="banji"/>
<!-- <typeAlias type="com.xiaomin.mapper.studentMapper" alias="studentMapper"/>-->
<!-- <typeAlias type="com.xiaomin.mapper.banjiMapper" alias="banjiMapper"/>-->
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${user}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="studentMapper.xml"/>
<mapper resource="banjiMapper.xml"/>
</mappers>
</configuration>***jdbc.properties的大概配置
user=你自己的用户名
password=你自己的密码
driver=com.mysql.cj.jdbc.Driver --8.x以上的connect就会有cj，旧版本没有cj
url=jdbc:mysql://localhost:3306/你自己的数据库
initsize = 5
maxsize = 501、studentMapper.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.xiaomin.mapper.studentMapper">
<resultMap id="studentMap" type="student">
<id column="stu_num" property="stuNum"/>
<result column="stu_name" property="stuName"/>
<result column="stu_sex" property="stuSex"/>
<result column="stu_age" property="stuAge"/>
<result column="stu_banjiId" property="stuBanjiId"/>
<result column="stu_banjiId" property="b.banjiId"/>
<collection property="b" ofType="banji">
<id column="banjiId" property="banjiId"/>
<result column="banji_xueYuan" property="banjiXueYuan"/>
<result column="banji_zhuanYe" property="banjiZhuanYe"/>
<result column="banji_order" property="banjiOrder"/>
</collection>
</resultMap>
<select id="getAllStudentByNum" resultMap="studentMap">
select * from homework01_student st,homework01_banji ba
where st.stu_banjiId=ba.banjiId and stu_num=#{stuNum}
</select>
<resultMap id="studentMap2" type="student">
<id column="stu_num" property="stuNum"/>
<result column="stu_name" property="stuName"/>
<result column="stu_sex" property="stuSex"/>
<result column="stu_age" property="stuAge"/>
<result column="stu_banjiId" property="stuBanjiId"/>
<result column="banjiId" property="b.banjiId"/>
<result column="banji_xueYuan" property="b.banjiXueYuan"/>
<result column="banji_zhuanYe" property="b.banjiZhuanYe"/>
<result column="banji_order" property="b.banjiOrder"/>
</resultMap>
<select id="getStudentByNum" resultMap="studentMap2">
select * from homework01_student st,homework01_banji ba
where st.stu_banjiId=ba.banjiId and stu_num=#{stuNum}
</select>
<select id="getStudent" resultMap="studentbanji">
select * from homework01_student
</select>
<resultMap id="studentbanji" type="student">
<id column="stu_num" property="stuNum"/>
<result column="stu_name" property="stuName"/>
<result column="stu_sex" property="stuSex"/>
<result column="stu_age" property="stuAge"/>
<result column="stu_banjiId" property="stuBanjiId"/>
<!--复杂的属性，需单独处理：对象： association 集合： collection
javaType:指定属性类型
集合中的泛型信息，使用ofType获取-->
<!-- 这个行不通，不知道为啥，哔站_狂神讲的mybatis 20集 多对一 -->
<!-- <association property="b" column="stu_banjiId" javaType="banji" select="getBanji"/>-->
<association property="b" column="stu_banjiId" javaType="banji" select="com.xiaomin.mapper.banjiMapper.getBanji"/>
</resultMap>
<!-- <select id="getBanji" resultType="banji">-->
<!-- select * from homework01_banji where banjiId=#{banjiId}-->
<!-- </select>-->
<!-- 按照结果嵌套处理-->
<select id="getStudent2" resultMap="studentbanji2">
select * from homework01_student s,homework01_banji b where banjiId=stu_banjiId
</select>
<resultMap id="studentbanji2" type="student">
<id column="stu_num" property="stuNum"/>
<result column="stu_name" property="stuName"/>
<result column="stu_sex" property="stuSex"/>
<result column="stu_age" property="stuAge"/>
<result column="stu_banjiId" property="stuBanjiId"/>
<association property="b" column="stu_banjiId" javaType="banji">
<id column="banjiId" property="banjiId"/>
<result column="banji_xueYuan" property="banjiXueYuan"/>
<result column="banji_zhuanYe" property="banjiZhuanYe"/>
<result column="banji_order" property="banjiOrder"/>
</association>
</resultMap>
<resultMap id="banjistudent" type="student">
<id column="stu_num" property="stuNum"/>
<result column="stu_name" property="stuName"/>
<result column="stu_sex" property="stuSex"/>
<result column="stu_age" property="stuAge"/>
<result column="stu_banjiId" property="stuBanjiId"/>
</resultMap>
<select id="getStudentByTeacherId" resultMap="banjistudent">
select * from homework01_student where stu_banjiId=#{bid}
</select>
</mapper>2、banjiMapper.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.xiaomin.mapper.banjiMapper">
<resultMap id="studentbanji" type="banji">
<id column="banjiId" property="banjiId"/>
<result column="banji_xueYuan" property="banjiXueYuan"/>
<result column="banji_zhuanYe" property="banjiZhuanYe"/>
<result column="banji_order" property="banjiOrder"/>
</resultMap>
<select id="getBanji" resultMap="studentbanji">
select * from homework01_banji where banjiId=#{banjiId}
</select>
<resultMap id="banjistudent" type="banji">
<id column="banjiId" property="banjiId"/>
<result column="banji_xueYuan" property="banjiXueYuan"/>
<result column="banji_zhuanYe" property="banjiZhuanYe"/>
<result column="banji_order" property="banjiOrder"/>
<collection property="s" ofType="student">
<id column="stu_num" property="stuNum"/>
<result column="stu_name" property="stuName"/>
<result column="stu_sex" property="stuSex"/>
<result column="stu_age" property="stuAge"/>
<result column="stu_banjiId" property="stuBanjiId"/>
</collection>
</resultMap>
<select id="getBanji2" resultMap="banjistudent">
select * from homework01_banji b,homework01_student s where s.stu_banjiId=b.banjiId and banjiId=#{bid}
</select>
<!-- 按照查询嵌套处理-->
<resultMap id="banjistudent2" type="banji">
<id column="banjiId" property="banjiId"/>
<result column="banji_xueYuan" property="banjiXueYuan"/>
<result column="banji_zhuanYe" property="banjiZhuanYe"/>
<result column="banji_order" property="banjiOrder"/>
<collection property="s" javaType="ArrayList" ofType="student"
select="com.xiaomin.mapper.studentMapper.getStudentByTeacherId"
column="banjiId"/>
</resultMap>
<select id="getBanji3" resultMap="banjistudent2">
select * from homework01_banji where banjiId=#{bid}
</select>
</mapper>3、studentMapper.java、banjiMapper.java
package com.xiaomin.mapper;
import com.xiaomin.pojo.student;
import java.util.List;
public interface studentMapper {
List<student> getStudent();
List<student> getStudent2();
student getStudentByTeacherId();
List<student> getAllStudentByNum(int stuNum);
student getStudentByNum(int stuNum);
}
package com.xiaomin.mapper;
import com.xiaomin.pojo.banji;
import org.apache.ibatis.annotations.Param;
import java.util.List;
public interface banjiMapper {
banji getBanji(int banjiId);
List<banji> getBanji2(@Param("bid") int banjiId);
List<banji> getBanji3(@Param("bid") int banjiId);
}
4、banjiMapperTest.java
package com.xiaomin.mapper;
import com.xiaomin.pojo.banji;
import com.xiaomin.util.mybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.jupiter.api.Test;
import java.util.List;
/**
* @author 解你忧
* @date 2022/03/25 23:14
* @product_namae mybatis-software2
* @product_namae IntelliJ IDEA
*/
public class banjiMapperTest {
SqlSession sqlSession=mybatisUtil.getSqlSession();
banjiMapper mapper=sqlSession.getMapper(banjiMapper.class);
Logger logger = Logger.getLogger(studentMapperTest.class);
@Test
public void getBanji(){
List<banji> banjiList = mapper.getBanji2(20010202);
for (banji banji : banjiList) {
System.out.println(banji);
}
}
@Test
public void getBanji2(){
List<banji> banjiList = mapper.getBanji3(20010202);
for (banji banji : banjiList) {
System.out.println(banji);
}
}
}
5、studentMapperTest.java
package com.xiaomin.mapper;
import com.xiaomin.pojo.student;
import com.xiaomin.util.mybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.jupiter.api.Test;
import java.util.List;
/**
* @author 解你忧
* @date 2022/03/22/23:14
*/
public class studentMapperTest {
SqlSession sqlSession= mybatisUtil.getSqlSession();
studentMapper mapper = sqlSession.getMapper(studentMapper.class);
Logger logger = Logger.getLogger(studentMapperTest.class);
@Test
public void getAllStudentByNum(){
List<student> studentAndBanjiInfo = mapper.getAllStudentByNum(2032002);
for (student student : studentAndBanjiInfo) {
System.out.println(student);
}
sqlSession.close();
}
@Test
public void getStudentByNum(){
student linmin = mapper.getStudentByNum(2032002);
System.out.println(linmin);
sqlSession.close();
}
@Test
public void getStudent(){
List<student> studentList = mapper.getStudent();
for (student student : studentList) {
System.out.println(student);
}
sqlSession.close();
}
@Test
public void getStudent2(){
List<student> studentList = mapper.getStudent2();
for (student student : studentList) {
System.out.println(student);
}
sqlSession.close();
}
}
本文来自博客园，作者：解你忧，转载请注明原文链接：https://www.cnblogs.com/jieniyou/p/16417727.html
