版权声明:本文为博主原创文章,版权归原作者小思所有,转载或者引用本文内容请注明来源及原作者 https://blog.csdn.net/zeal9s/article/details/83793725
前言:本项目是使用idea进行开发,数据库使用的是Mysql。
1.搭建maven项目,引入mybatis需要的依赖
默认没有java、resources、test等文件夹,习惯性建立这几个文件夹,建立文件夹的时候注意标记文件夹的用途(不然编译器无法识别,无法编译代码)
pom.xml(注意要将实体包下面的xml文件设置可编译)
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>Mybatis_05</groupId>
<artifactId>Mybatis_05</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>Mybatis_05 Maven Webapp</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!--引入Mybatis依赖 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.1</version>
</dependency>
<!--引入MySql依赖 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.43</version>
</dependency>
</dependencies>
<build>
<finalName>Mybatis_05</finalName>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.0.0</version>
</plugin>
<!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.20.1</version>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.0</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
2.项目模块图:
3.在resources目录下新建mybatis的核心配置文件mybatis-config.xml
mybatis-config.xml
<?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>
<!--给com.zs.entity包取别名-->
<typeAliases>
<package name="com.zs.entity"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<!--配置获取数据库连接实例的数据源 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url"
value="jdbc:mysql://localhost:3306/zs?characterEncoding=utf-8" />
<property name="username" value="root" />
<property name="password" value="1234" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/zs/entity/Students.xml"></mapper>
</mappers>
</configuration>
4.建立与数据库对应的实体包,包下建立类与对应的xml文件(这里没有使用接口调用方法,是使用xml文件调用方法)
Students.java
package com.zs.entity;
import java.util.List;
/**
* @author 小思
* @PackageName:PACKAGE_NAME
* @ClassName: Students
* @Description:对应数据库的Students表
* @date 2018/11/4 22:05
*/
public class Students {
private Integer sid;//学生的id
private String sname;//学生的姓名
private List<Course> courses;
public Integer getSid() {
return sid;
}
public void setSid(Integer sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public List<Course> getCourses() {
return courses;
}
public void setCourses(List<Course> courses) {
this.courses = courses;
}
}
Course.java
package com.zs.entity;
import java.util.List;
/**
* @author 小思
* @PackageName:PACKAGE_NAME
* @ClassName: Course
* @Description:对应数据库的Course表
* @date 2018/11/4 22:06
*/
public class Course {
private Integer cid;//课程的Id
private String cname;//课程的名称
private List<Students> students;//单个课程对应的多个学生
public Integer getCid() {
return cid;
}
public void setCid(Integer cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public List<Students> getStudents() {
return students;
}
public void setStudents(List<Students> students) {
this.students = students;
}
}
Students.xml(这里测试多对多的一半,另一半一样的写法,这里的示例是根据学生的Id,查询到相应学生的信息)
<?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="students">
<!--查询学生的信息(包括课程)-->
<select id="studentInfo" parameterType="int" resultMap="studentsCourseInfo">
select * from Students where sid=#{sid}
</select>
<!--学生对应的课程集合-->
<resultMap id="studentsCourseInfo" type="Students">
<id property="sid" column="sid"></id>
<result property="sname" column="sname"></result>
<!--学生对应的课程集合-->
<collection property="courses" ofType="Course" column="sid" select="courseInfo">
<id property="cid" column="cid"></id>
<result property="cname" column="cname"></result>
</collection>
</resultMap>
<!--课程集合-->
<select id="courseInfo" parameterType="int" resultType="Course">
select * from course c inner join stu_cou sc on c.cid=sc.cid where sc.sid=#{sid}
</select>
</mapper>
5.在test文件夹下新建com.zs.test文件夹,并且新建单元测试类TestManyToMany.java
TestManyToMany.java
package com.zs.test;
import com.zs.entity.Course;
import com.zs.entity.Students;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
/**
* @author 小思
* @PackageName:com.zs.test
* @ClassName: TestManyToMany
* @Description:
* @date 2018/11/4 22:16
*/
public class TestManyToMany {
private SqlSessionFactory sessionFactory;
private SqlSession sqlSession;
@Before
public void before(){
//从配置文件获取SqlSessionFactory实例
sessionFactory = new SqlSessionFactoryBuilder().build(getClass().getClassLoader().getResourceAsStream("mybatis-config.xml"));
sqlSession = sessionFactory.openSession();
}
@Test
public void test(){
Students s=sqlSession.selectOne("students.studentInfo",1);
//查询学生
System.out.print(s.getSname()+"______");
//查询学生对应的课程信息
for (Course course : s.getCourses()) {
System.out.print(course.getCname()+"\t");
}
}
@After
public void after(){
sqlSession.commit();
sqlSession.close();
}
}
6.运行测试类
说在最后的话:编写实属不易,若喜欢或者对你有帮助记得点赞+关注或者收藏哦~