Java SSM框架之MyBatis3（四）MyBatis之一對1、一對多、多對多

項目搭建Springboot 1.5

 pom.xml

<?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>cn.cnki</groupId>
    <artifactId>ref</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>ref</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.14.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- mysql鏈接 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!-- mybatis -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <!-- 阿里系的Druid依賴包 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.5</version>
        </dependency>
        <!--pageHelper分頁插件 -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>4.3.18.RELEASE</version>
        </dependency>
        <!--To display the auto-configuration report re-run your application with 'debug' enabled. -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.0.7.Final</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

View Code

application.properties

server.port = 8080
########################################################
###mybatis-mysql-druid
########################################################
#sql配置文件的路徑
mybatis.mapper-locations="classpath:mapper/*.xml"
#這個是mybatis全局配置文件路徑
mybatis.config-location="classpath:mapper/config/mybatis-config.xml"
#實體類路徑
mybatis.type-aliases-package="cn.cnki.ref.pojo"
# 驅動配置信息
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.url = jdbc:mysql://127.0.0.1:3306/springbootmybatis?useUnicode=true&characterEncoding=utf-8
spring.datasource.username = root
spring.datasource.password = root
spring.datasource.driverClassName = com.mysql.jdbc.Driver
########################################################

View Code

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>
    <properties>
        <property name="dialect" value="mysql" />
    </properties>
    <settings>
        <!-- 這個配置使全局的映射器啓用或禁用緩存。系統默認值是true，設置只是爲了展現出來 -->
        <setting name="cacheEnabled" value="true" />
        <!-- 全局啓用或禁用延遲加載。當禁用時，全部關聯對象都會即時加載。 系統默認值是true，設置只是爲了展現出來 -->
        <setting name="lazyLoadingEnabled" value="true" />
        <!-- 容許或不容許多種結果集從一個單獨的語句中返回（須要適合的驅動）。 系統默認值是true，設置只是爲了展現出來 -->
        <setting name="multipleResultSetsEnabled" value="true" />
        <!--使用列標籤代替列名。不一樣的驅動在這方便表現不一樣。參考驅動文檔或充分測試兩種方法來決定所使用的驅動。 系統默認值是true，設置只是爲了展現出來 -->
        <setting name="useColumnLabel" value="true" />
        <!--容許 JDBC 支持生成的鍵。須要適合的驅動。若是設置爲 true 則這個設置強制生成的鍵被使用，儘管一些驅動拒絕兼容但仍然有效（好比 
            Derby）。 系統默認值是false，設置只是爲了展現出來 -->
        <setting name="useGeneratedKeys" value="false" />
        <!--配置默認的執行器。SIMPLE 執行器沒有什麼特別之處。REUSE 執行器重用預處理語句。BATCH 執行器重用語句和批量更新 系統默認值是SIMPLE，設置只是爲了展現出來 -->
        <setting name="defaultExecutorType" value="SIMPLE" />
        <!--設置超時時間，它決定驅動等待一個數據庫響應的時間。 系統默認值是null，設置只是爲了展現出來 -->
        <setting name="defaultStatementTimeout" value="25000" />
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>
    <plugins>
        <plugin interceptor="com.github.pagehelper.PageHelper">
            <property name="dialect" value="mysql" />
            <property name="offsetAsPageNum" value="true" />
            <property name="rowBoundsWithCount" value="true" />
            <property name="pageSizeZero" value="true" />
            <property name="reasonable" value="true" />
        </plugin>
    </plugins>
</configuration>

View Code

RefApplication

package cn.cnki.ref;

import com.alibaba.druid.pool.DruidDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;


@SpringBootApplication(exclude={DataSourceAutoConfiguration.class,HibernateJpaAutoConfiguration.class})
@MapperScan("cn.cnki.ref.mapper")
public class RefApplication {

    public static void main(String[] args) {
        SpringApplication.run(RefApplication.class, args);
    }

    //datasource注入
    @Bean(initMethod = "init", destroyMethod = "close")
    @ConfigurationProperties(prefix = "spring.datasource")
    public DruidDataSource dataSource() {
        return new DruidDataSource();
    }

    //mybatis SQLSession注入
    @Bean
    public SqlSessionFactory sqlSessionFactoryBean() throws Exception {
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource());
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources("classpath*:/mapper/*Mapper.xml"));
        return sqlSessionFactoryBean.getObject();
    }

    //事務支持
    @Bean
    public PlatformTransactionManager transactionManager() {
        return new DataSourceTransactionManager(dataSource());
    }

}

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一對一association 

 　　每一個學生對應一張身份證，每張身份證上有身份證號cardId、開始日期、結束日期。而且創建與student表的外鍵關係。

cardid表、student表

/*Table structure for table `cardid` */

DROP TABLE IF EXISTS `cardid`;

CREATE TABLE `cardid` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `cardId` varchar(18) NOT NULL,
  `sid` int(10) NOT NULL,
  `beginTime` datetime NOT NULL,
  `endTime` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

/*Data for the table `cardid` */

insert  into `cardid`(`id`,`cardId`,`sid`,`beginTime`,`endTime`) values (1,'412728199513161601',1,'2008-07-19 11:19:27','2018-07-19 11:19:30'),(2,'412728199513161602',2,'2008-04-01 11:20:13','2018-04-01 11:20:13'),(3,'412728199513161603',3,'2008-07-19 11:21:06','2018-07-19 11:21:16');

/*Table structure for table `student` */

DROP TABLE IF EXISTS `student`;

CREATE TABLE `student` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

/*Data for the table `student` */

insert  into `student`(`id`,`name`) values (1,'張三'),(2,'李四'),(3,'王五');

View Code

Cardid實體

package cn.cnki.ref.pojo;

import java.util.Date;

public class Cardid {
    private Integer id;

    private String cardid;

    private Integer sid;

    private Date begintime;

    private Date endtime;

    private Student student;

    public Student getStudent() {
        return student;
    }
    public void setStudent(Student student) {
        this.student = student;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getCardid() {
        return cardid;
    }

    public void setCardid(String cardid) {
        this.cardid = cardid == null ? null : cardid.trim();
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }

    public Date getBegintime() {
        return begintime;
    }

    public void setBegintime(Date begintime) {
        this.begintime = begintime;
    }

    public Date getEndtime() {
        return endtime;
    }

    public void setEndtime(Date endtime) {
        this.endtime = endtime;
    }
}

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Student實體

package cn.cnki.ref.pojo;

public class Student {
    private Integer id;

    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }
}

View Code

CardidMapper

package cn.cnki.ref.mapper;

import cn.cnki.ref.pojo.Cardid;
import java.util.List;

public interface CardidMapper {
    /**
     * 獲取包括學生信息的身份證列表
     * @return
     */
    public List<Cardid>  getListIdOfStudent();
}

View Code

CardidMapper.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="cn.cnki.ref.mapper.CardidMapper" >

  <!--  學生表與身份證表的一對一映射-->
  <resultMap type="cn.cnki.ref.pojo.Cardid" id="IDCardOfStudentMap">
    <id property="id" column="id"  jdbcType="INTEGER"/>
    <result property="cardid" column="cardid"  jdbcType="VARCHAR" />
    <result property="begintime" column="beginTime" jdbcType="TIMESTAMP"/>
    <result property="endtime" column="endTime" jdbcType="TIMESTAMP"/>
    <association property="student" javaType="cn.cnki.ref.pojo.Student">
      <id property="id" column="id" jdbcType="INTEGER"/>
      <result property="name" column="name" jdbcType="VARCHAR"/>
    </association>
  </resultMap>

  <!-- 查出帶有學生信息的身份證列表 -->
  <select id="getListIdOfStudent" resultMap="IDCardOfStudentMap">
    SELECT * FROM cardid a,student b WHERE a.sid=b.id;
  </select>


</mapper>

View Code

CardidController

package cn.cnki.ref.controller;

import cn.cnki.ref.mapper.CardidMapper;
import cn.cnki.ref.pojo.Cardid;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/Cardid")
public class CardidController {

    @Autowired
    private CardidMapper CardidMapper;
    @RequestMapping(value = "/GetListIdOfStudent", method = RequestMethod.GET)
    public List<Cardid> index() {
        return CardidMapper.getListIdOfStudent();
    }

}

View Code

測試

http://localhost:8080/Cardid/GetListIdOfStudent

一對多Collection

 　　一我的有好多本書，每本書的主人只有一我的。當咱們查詢某我的擁有的全部書籍時，就涉及到了一對多的映射關係。

 book表

/*Table structure for table `book` */

DROP TABLE IF EXISTS `book`;

CREATE TABLE `book` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  `sid` int(10) NOT NULL,
  `price` decimal(10,0) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

/*Data for the table `book` */

insert  into `book`(`id`,`name`,`sid`,`price`) values (1,'《黑客與畫家》',1,'45'),(2,'《北方的空地》',1,'40');

View Code

Book實體

package cn.cnki.ref.pojo;

public class Book {
    private Integer id;

    private String name;

    private Integer sid;

    private Long price;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }

    public Long getPrice() {
        return price;
    }

    public void setPrice(Long price) {
        this.price = price;
    }
}

View Code

Student實體

package cn.cnki.ref.pojo;

import java.util.List;

public class Student {
    private Integer id;

    private String name;

    private List<Book> books;

    public Student() {

    }


    public List<Book> getBooks() {
        return books;
    }


    public void setBooks(List<Book> books) {
        this.books = books;
    }


    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }
}

View Code

StudentMapper

package cn.cnki.ref.mapper;

import cn.cnki.ref.pojo.Student;

import java.util.List;

public interface StudentMapper {

    /**
     * 根據id查詢
     * @param id
     * @return
     */
    public Student getById(Integer id);

    /**
     * 查詢所有
     * @return
     */
    public List<Student> list();

    /**
     * 插入
     * @param student
     */
    public int insert(Student student);
    /**
     * 主鍵回填的插入
     * @param student
     * @return
     */
    public int insertToId(Student student);

    /**
     * 根據student的id修改
     * @param student
     */
    public void update(Student student);

    /**
     * 根據id刪除
     * @param id
     */
    public void delete(Integer id);

    /**
     * 根據id查詢全部的書
     * @param id
     */
    public Student selectBookById(Integer id);

}

View Code

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="cn.cnki.ref.mapper.StudentMapper">

    <!-- 根據id查詢 -->
    <select id="getById" parameterType="int" resultType="cn.cnki.ref.pojo.Student">
    select * from student where id=#{id}
    </select>
    <!-- 查詢全部 -->
    <select id="list" parameterType="int" resultType="cn.cnki.ref.pojo.Student">
    select * from student
    </select>

    <!-- 插入一個學生 -->
    <insert id="insert" parameterType="cn.cnki.ref.pojo.Student">
    insert into student(name) values(#{name})
    </insert>
    <!-- 主鍵回填的插入 -->
    <insert id="insertToId" parameterType="cn.cnki.ref.pojo.Student" useGeneratedKeys="true" keyProperty="id">
    insert into student(name) values(#{name})
    </insert>

    <!-- 根據id修改學生信息 -->
    <update id="update" parameterType="cn.cnki.ref.pojo.Student">
    update student set name=#{name} where id=#{id}
    </update>

    <!-- 根據id刪除學生 -->
    <delete id="delete" parameterType="int">
    delete  from student where id=#{id}
    </delete>

    <resultMap type="cn.cnki.ref.pojo.Student" id="bookMap">
        <id property="id" column="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
        <collection property="books" ofType="cn.cnki.ref.pojo.Book" javaType="ArrayList" >
            <id property="id" column="bid" jdbcType="INTEGER"/>
            <result property="name" column="bname" jdbcType="VARCHAR" />
            <result property="price" column="price" jdbcType="DECIMAL"/>
        </collection>
    </resultMap>
    <!--根據id查詢全部的書  -->
    <select id="selectBookById" parameterType="int" resultMap="bookMap">
      select a.*,b.id bid,b.name bname,b.price from student a,book b where a.id=b.sid and a.id=#{id};
    </select>
</mapper>

View Code

StudentController

package cn.cnki.ref.controller;

import cn.cnki.ref.mapper.StudentMapper;
import cn.cnki.ref.pojo.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
public class StudentController {
    @Autowired
    private StudentMapper studentMapper;

    /**
     * 根據id查詢學生
     * @param id
     * @return
     */
    @GetMapping("/student/{id}")
    public Student getById(@PathVariable("id") Integer id) {

        Student student = studentMapper.getById(id);
        return student;

    }

    /**
     * 查詢所有
     * @return
     */
    @GetMapping("/students")
    public List<Student> list(){
        List<Student> students = studentMapper.list();
        return students;
    }

    /**
     * 插入
     * @param student
     */
    @PostMapping("/student")
    public void insert( Student student) {
        studentMapper.insert(student);
    }

    /**
     * 修改
     * @param student
     */
    @PutMapping("/student/{id}")
    public void update(Student student,@PathVariable("id")Integer id) {
        studentMapper.update(student);
    }

    /**
     * 根據id刪除
     * @param id
     */
    @DeleteMapping("/student/{id}")
    public void delete(@PathVariable("id") Integer id) {
        studentMapper.delete(id);
    }

    /**
     * 根據id查詢全部的書
     */
    @GetMapping("/student/book/{id}")
    public Student getBooks(@PathVariable("id") Integer id) {
        Student student = studentMapper.selectBookById(id);
        return student;
    }

}

View Code

測試

 http://localhost:8080//student/book/1

 

多對多——查詢某個學生所選的所有課程代碼實現

　　以前咱們探討了一對1、一對多的映射關係，今天咱們來討論多對多的映射關係。

　　多對多，其實能夠拆成多個一對多來理解。

　　好比：

　　學生-------課程----------學生選課的關係：

　　（1）查詢某個學生所選的所有課程；

　　（2）查詢選修某個課程的所有學生；

 course表、student_course表

/*Table structure for table `course` */

DROP TABLE IF EXISTS `course`;

CREATE TABLE `course` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

/*Data for the table `course` */

insert  into `course`(`id`,`name`) values (1,'語文'),(2,'數學'),(3,'英語');

/*Table structure for table `student_course` */

DROP TABLE IF EXISTS `student_course`;

CREATE TABLE `student_course` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `sid` int(10) NOT NULL,
  `cid` int(10) NOT NULL,
  `score` int(3) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

/*Data for the table `student_course` */

insert  into `student_course`(`id`,`sid`,`cid`,`score`) values (1,1,1,91),(2,1,2,92),(3,1,3,93),(4,2,1,81),(5,2,2,82),(6,2,3,83),(7,3,1,71),(8,3,2,72),(9,3,3,73);

View Code

Course實體

package cn.cnki.ref.pojo;

public class Course {
    private Integer id;

    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }
}

View Code

 StudentCourse實體

package cn.cnki.ref.pojo;

import java.util.List;

public class StudentCourse {
    private Integer id;

    private Integer sid;

    private Integer cid;

    private Integer score;

    private List<Student> students;//一門課有多名學生

    private List<Course> courses;//一名學生有多門課

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }

    public Integer getCid() {
        return cid;
    }

    public void setCid(Integer cid) {
        this.cid = cid;
    }

    public Integer getScore() {
        return score;
    }

    public void setScore(Integer score) {
        this.score = score;
    }

    public List<Student> getStudents() {
        return students;
    }
    public void setStudents(List<Student> students) {
        this.students = students;
    }
    public List<Course> getCourses() {
        return courses;
    }
    public void setCourses(List<Course> courses) {
        this.courses = courses;
    }
}

View Code

在Studnent實體中添加StudentCourse列表

package cn.cnki.ref.pojo;

import java.util.List;

public class Student {
    private Integer id;

    private String name;

    private List<Book> books;//一名學生有多本書

    private List<StudentCourse> studentCourses;

    public Student() {

    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public List<Book> getBooks() {
        return books;
    }

    public List<StudentCourse> getStudentCourses() {
        return studentCourses;
    }

    public void setStudentCourses(List<StudentCourse> studentCourses) {
        this.studentCourses = studentCourses;
    }

    public void setBooks(List<Book> books) {
        this.books = books;
    }
}

View Code

StudentCourseMapper

package cn.cnki.ref.mapper;

import cn.cnki.ref.pojo.Student;

public interface  StudentCourseMapper {
    /**
     * 根據學生id查詢該學生選修的全部課程
     * @param id
     * @return
     */
    public Student selectCourseById(Integer id);
}

View Code

StudentCourseMapper.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="cn.cnki.ref.mapper.StudentCourseMapper">

    <resultMap type="cn.cnki.ref.pojo.Student" id="studentMap">
        <id property="id" column="id" jdbcType="INTEGER"/>
        <result property="name" column="name" jdbcType="VARCHAR"/>
    </resultMap>

    <resultMap type="cn.cnki.ref.pojo.Student" id="courseMap" extends="studentMap">
        <collection property="studentCourses" ofType="cn.cnki.ref.pojo.StudentCourse" javaType="ArrayList">
            <result property="score" column="score" jdbcType="INTEGER"/>
            <collection property="courses" ofType="cn.cnki.ref.pojo.Course" javaType="ArrayList">
                <id property="id" column="cid" jdbcType="INTEGER"/>
                <result property="name" column="cname" jdbcType="VARCHAR"/>
            </collection>
        </collection>
    </resultMap>

    <!-- 根據學生id查詢該學生選修的全部課程 -->
    <select id="selectCourseById" parameterType="int" resultMap="courseMap" >
        select a.*,b.score,c.id cid,c.name cname from student a,student_course b,course c where a.id=b.sid and b.cid=c.id and a.id=#{id}
    </select>
</mapper>

View Code

StudentCourseController

package cn.cnki.ref.controller;

import cn.cnki.ref.mapper.StudentCourseMapper;
import cn.cnki.ref.pojo.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class StudentCourseController {
    @Autowired
    private StudentCourseMapper studentCourseMapper;

    /************/

    /**
     * 根據學生id查詢該學生選修的全部課程
     * @param id
     * @return
     */
    @GetMapping("/student/course/{id}")
    public Student selectCourseById(@PathVariable("id") Integer id) {
        Student student = studentCourseMapper.selectCourseById(id);
        return student;
    }
}

View Code

測試

http://localhost:8080/student/course/1

多對多——查詢選修某個課程的所有學生代碼實現

Course實體中添加StudentCourse列表

package cn.cnki.ref.pojo;

import java.util.List;

public class Course {
    private Integer id;

    private String name;

    private List<StudentCourse> studentCourses;//

    public List<StudentCourse> getStudentCourses() {
        return studentCourses;
    }
    public void setStudentCourses(List<StudentCourse> studentCourses) {
        this.studentCourses = studentCourses;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }
}

View Code

CourseMapper

package cn.cnki.ref.mapper;

import cn.cnki.ref.pojo.Course;

public interface CourseMapper {
    /**
     * 根據課程id查詢選修此課程的所有學生
     * @param id
     * @return
     */
    public Course selectStudentById(Integer id);

}

View Code

CourseMapper.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="cn.cnki.ref.mapper.CourseMapper">
    <resultMap type="cn.cnki.ref.pojo.Course" id="courseMap">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
    </resultMap>
    <resultMap type="cn.cnki.ref.pojo.Course" id="studentMap" extends="courseMap">
        <collection property="studentCourses" ofType="cn.cnki.ref.pojo.StudentCourse">
            <result property="score" column="score"/>
            <collection property="students" ofType="cn.cnki.ref.pojo.Student">
                <id property="id" column="sid" jdbcType="INTEGER"/>
                <result property="name" column="sname" jdbcType="VARCHAR"/>
            </collection>
        </collection>
    </resultMap>
    <!-- 根據課程id查詢選修此課程的所有學生 -->
    <select id="selectStudentById" parameterType="int" resultMap="studentMap">
     select a.*,b.score,c.id sid,c.name sname from student c,student_course b,course a where a.id=b.cid and b.sid=c.id and a.id=#{id}
    </select>
</mapper>

View Code

CourseController

package cn.cnki.ref.controller;

import cn.cnki.ref.mapper.CourseMapper;
import cn.cnki.ref.pojo.Course;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class CourseController {
    @Autowired
    private CourseMapper courseMapper;

    /**
     * 根據課程id查詢選修此課程的所有學生
     * @param id
     * @return
     */
    @GetMapping("/course/student/{id}")
    public Course selectStudentById(@PathVariable("id")Integer id) {

        Course course = courseMapper.selectStudentById(id);
        return course;

    }

}

View Code

測試

http://localhost:8080//course/student/1

 

 

源碼下載

http://www.cnblogs.com/TimerHotel/tag/mybatis/

https://www.cnblogs.com/ashleyboy/p/9271597.html