ManyToMany（基于注解）使用之进阶（中级版）

野性酷女 2022-07-21 00:08 130阅读 0赞

社团和成员就是多对多的关系，一个成员有多个社团，一个社团也有多个成员，这里的多对多映射采用中间表连接的映射策略，建立中间表的映射策略，建立中间表分别引入俩边的主键作为外键。通过中间表映射俩个表之间的关系。

下面就以社团类和成员类为例介绍多对多的映射关系的实例

Club实体类

package com.cn.entity;
    
    import java.io.Serializable;
    import java.util.Date;
    import java.util.HashSet;
    import java.util.Set;
    
    import javax.persistence.CascadeType;
    import javax.persistence.Entity;
    import javax.persistence.FetchType;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinTable;
    import javax.persistence.ManyToMany;
    import javax.persistence.ManyToOne;
    import javax.persistence.Table;
    
    import org.hibernate.annotations.Cache;
    import org.hibernate.annotations.CacheConcurrencyStrategy;
    
    import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
    
    /** * @ClassName: Club * @Description: 社团的实体类 * @author: Administrator * @date: 2016年7月6日 下午3:27:43 */
    @Entity //实体类
    @Table(name="iyo_club",catalog="iyo") //哪个数据库那张表
    @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) //二级缓存
    public class Club implements Serializable{ 
    
        /** * @fieldName: serialVersionUID * @fieldType: long * @Description: */
        private static final long serialVersionUID = -1576706279212597880L;
    
        private Integer clubId;//社团ID
        private String clubIntroction;//社团简介
        private String ClubName;//社团名称
        private Integer clubLevel;//社团等级
        private Integer clubNumber;//社团人数
        private Date clubCreateTime;//创建时间
        private User user;//创始人
        private College college;//所属学院
        private Set<Member> member = new HashSet<Member>();
    
        public Club() {
            //super();
        }
    
        public Club(String clubIntroction, String clubName, Integer clubLevel, Integer clubNumber, Date clubCreateTime,
                User user, College college) {
            //super();
            this.clubIntroction = clubIntroction;
            ClubName = clubName;
            this.clubLevel = clubLevel;
            this.clubNumber = clubNumber;
            this.clubCreateTime = clubCreateTime;
            this.user = user;
            this.college = college;
        }
    
        @Id //主键
        @GeneratedValue(strategy = GenerationType.IDENTITY) //数据库自增
        public Integer getClubId() {
            return clubId;
        }
    
        public void setClubId(Integer clubId) {
            this.clubId = clubId;
        }
    
        public String getClubIntroction() {
            return clubIntroction;
        }
    
        public void setClubIntroction(String clubIntroction) {
            this.clubIntroction = clubIntroction;
        }
    
        public String getClubName() {
            return ClubName;
        }
    
        public void setClubName(String clubName) {
            ClubName = clubName;
        }
    
        public Integer getClubLevel() {
            return clubLevel;
        }
    
        public void setClubLevel(Integer clubLevel) {
            this.clubLevel = clubLevel;
        }
    
        public Integer getClubNumber() {
            return clubNumber;
        }
    
        public void setClubNumber(Integer clubNumber) {
            this.clubNumber = clubNumber;
        }
    
        public Date getClubCreateTime() {
            return clubCreateTime;
        }
    
        public void setClubCreateTime(Date clubCreateTime) {
            this.clubCreateTime = clubCreateTime;
        }
    
        //多对一外键关联
        @JsonIgnoreProperties(value={
       "permission"})
        @ManyToOne
        @Cache(usage=CacheConcurrencyStrategy.READ_WRITE)//缓存
        @JoinTable(name="iyo_club",joinColumns=@JoinColumn(name="userId"),inverseJoinColumns=@JoinColumn(name="userId"))
        public User getUser() {
            return user;
        }
    
        public void setUser(User user) {
            this.user = user;
        }
    
        @ManyToOne
        @Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
        @JoinTable(name = "iyo_club", joinColumns = @JoinColumn(name = "collegeId") , inverseJoinColumns = @JoinColumn(name = "collegeId") )
        public College getCollege() {
            return college;
        }
    
        public void setCollege(College college) {
            this.college = college;
        }
    
    
    
        @ManyToMany(targetEntity=Member.class,cascade=CascadeType.PERSIST,fetch = FetchType.EAGER)
        @Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
        //@JoinTable(name = "iyo_memberdesc", joinColumns = { @JoinColumn(name = "clubId") }, inverseJoinColumns = { 
            // @JoinColumn(name = "memberId") })
        @JoinTable(name="iyo_memberdesc",catalog="iyo",joinColumns = {
       @JoinColumn(name = "clubId",nullable = false, updatable = false)},inverseJoinColumns = {
       @JoinColumn(name="memberId",nullable = false, updatable = false)})
        public Set<Member> getMember() {
            return member;
        }
    
        public void setMember(Set<Member> member) {
            this.member = member;
        }
    }

成员类

package com.cn.entity;
    
    import java.io.Serializable;
    import java.util.Date;
    import java.util.HashSet;
    import java.util.Set;
    
    import javax.persistence.CascadeType;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.FetchType;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinTable;
    import javax.persistence.ManyToMany;
    import javax.persistence.ManyToOne;
    import javax.persistence.OneToOne;
    import javax.persistence.Table;
    
    import org.hibernate.annotations.Cache;
    import org.hibernate.annotations.CacheConcurrencyStrategy;
    
    import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
    
    /** * @ClassName: Member * @Description: 成员的实体类 * @author: Administrator * @date: 2016年7月7日 下午1:39:57 */
    @Entity // 实体类
    @Table(name = "iyo_member", catalog = "iyo") // 哪个数据库哪张表
    @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) // 二级缓存
    public class Member implements Serializable { 
    
        /** * @fieldName: serialVersionUID * @fieldType: long * @Description: */
        private static final long serialVersionUID = 6370397842913431307L;
    
        private Integer memberId;// 成员id
        private String memberClass;// 成员所在的班级
        private String memberMajor;// 所在专业
        private String memberName;// 名字
        private String memberIphone;// 电话
        private Integer memberCard;// 学号
        private Date memberDate;// 加入的时间
        private College college;// 所在学院
        private User user;// 注册id
        private Integer memberCardId;// 卡号
        private Set<Club> club = new HashSet<Club>();// 成员持有的社团集合
    
        public Member() {
    
        }
    
        public Member(String memberClass, String memberMajor, String memberName, String memberIphone, Integer memberCard,
                Date memberDate, College college, User user, Integer memberCardId) {
            this.memberClass = memberClass;
            this.memberMajor = memberMajor;
            this.memberName = memberName;
            this.memberIphone = memberIphone;
            this.memberCard = memberCard;
            this.memberDate = memberDate;
            this.college = college;
            this.user = user;
            this.memberCardId = memberCardId;
        }
    
        @Id // 主键
        @GeneratedValue(strategy = GenerationType.IDENTITY) // 自增
        public Integer getMemberId() {
            return memberId;
        }
    
        public void setMemberId(Integer memberId) {
            this.memberId = memberId;
        }
    
        public String getMemberClass() {
            return memberClass;
        }
    
        public void setMemberClass(String memberClass) {
            this.memberClass = memberClass;
        }
    
        public String getMemberMajor() {
            return memberMajor;
        }
    
        public void setMemberMajor(String memberMajor) {
            this.memberMajor = memberMajor;
        }
    
        public String getMemberName() {
            return memberName;
        }
    
        public void setMemberName(String memberName) {
            this.memberName = memberName;
        }
    
        @Column(name = "memberIphone", unique = true) // 表示数据库中该字段是唯一的
        public String getMemberIphone() {
            return memberIphone;
        }
    
        public void setMemberIphone(String memberIphone) {
            this.memberIphone = memberIphone;
        }
    
        public Integer getMemberCard() {
            return memberCard;
        }
    
        public void setMemberCard(Integer memberCard) {
            this.memberCard = memberCard;
        }
    
        public Date getMemberDate() {
            return memberDate;
        }
    
        public void setMemberDate(Date memberDate) {
            this.memberDate = memberDate;
        }
    
        @Column(name = "memberCardId", unique = true)
        public Integer getMemberCardId() {
            return memberCardId;
        }
    
        public void setMemberCardId(Integer memberCardId) {
            this.memberCardId = memberCardId;
        }
    
        @ManyToOne
        @Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
        @JoinTable(name = "iyo_member", joinColumns = @JoinColumn(name = "collegeId") , inverseJoinColumns = @JoinColumn(name = "collegeId") )
        public College getCollege() {
            return college;
        }
    
        public void setCollege(College college) {
            this.college = college;
        }
    
        // 一对一的外键关联
        @JsonIgnoreProperties(value = { "permission" })
        @OneToOne
        @Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
        @JoinTable(name = "iyo_member", joinColumns = @JoinColumn(name = "userId") , inverseJoinColumns = @JoinColumn(name = "userId") )
        public User getUser() {
            return user;
        }
    
        public void setUser(User user) {
            this.user = user;
        }
    
    
    
    // @JsonIgnoreProperties(value = { "user", "college" }) // 忽略属性
    // @ManyToMany(mappedBy="member",cascade=CascadeType.MERGE)
    // @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) // 缓存属性
    // @JoinTable(name = "iyo_memberdesc", joinColumns = { @JoinColumn(name = "memberId",referencedColumnName="memberId") }, inverseJoinColumns = { 
    // @JoinColumn(name = "clubId",referencedColumnName="clubId") })
    // @JoinTable(name="iyo_memberdesc",catalog="iyo",joinColumns =
        // {@JoinColumn(name = "memberId",nullable = false, updatable =
        // false)},inverseJoinColumns = {@JoinColumn(name="clubId",nullable = false,
        // updatable = false)})
        @JsonIgnoreProperties(value = { "user", "college" }) // 忽略属性
        @ManyToMany(targetEntity=Club.class,cascade=CascadeType.PERSIST,fetch = FetchType.EAGER)
        @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) // 缓存属性
        @JoinTable(name="iyo_memberdesc",catalog="iyo",joinColumns = {
       @JoinColumn(name = "memberId",nullable = false, updatable = false)},inverseJoinColumns = {
       @JoinColumn(name="clubId",nullable = false, updatable = false)})
        public Set<Club> getClub() {
            return club;
        }
    
        public void setClub(Set<Club> club) {
            this.club = club;
        }
    }

测试类

package com.cn.service;
    
    import java.util.Date;
    import java.util.HashSet;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Set;
    
    import org.apache.log4j.Logger;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.test.context.ContextConfiguration;
    import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
    
    import com.alibaba.fastjson.JSON;
    import com.cn.entity.Club;
    import com.cn.entity.College;
    import com.cn.entity.Member;
    import com.cn.entity.Page;
    import com.cn.entity.User;
    
    /** * @ClassName: TestMemberService * @Description: 新闻类的测试类 * @author: Administrator * @date: 2016年7月4日 下午2:57:05 */
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(locations = { "classpath:spring.xml", "classpath:spring-hibernate.xml" })
    public class TestMemberService {
    
        private static final Logger LOGGER = Logger.getLogger(TestMemberService.class);
    
        @Autowired
        private MemberService memberService;
    
        @Autowired
        private ClubService clubService;
    
        @Test
        public void save() {
            Member member = new Member();
            member = memberService.get(14);
            Member member1 = memberService.get(12);
            // Integer id = memberService.save(member);
            Set<Member> st = new HashSet<Member>();
            st.add(member);
            st.add(member1);
            Club club = new Club();
            club = clubService.get(31);
        //  club.getMember().add(member);
            System.out.println(club.getClubId());
            clubService.save(club);
            //LOGGER.info(JSON.toJSONString(id));
        }
    
        @Test
        public void savess() {
            Club club = new Club();
            club = clubService.get(37);
            // Integer id = memberService.save(member);
            Set<Club> st = new HashSet<Club>();
            st.add(club);
            Member member = new Member();
            member = memberService.get(12);
            //ManyToMang的多对多测插入
            member.getClub().add(club);
            memberService.saveOrUpdate(member);
    
    
            //LOGGER.info(JSON.toJSONString(id));
        }
    
        @Test
        public void saves() {
            Member member = new Member();
            member.setMemberCard(2013081426);
            member.setMemberClass("计科13w4");
            member.setMemberDate(new Date());
            member.setMemberIphone("1589e2436786");
            member.setMemberMajor("计算机科学r与技术");
            member.setMemberName("琪q琪");
            User user = new User();
            user.setUserId(2);
            member.setUser(user);
            College college = new College();
            college.setCollegeId(2);
            member.setCollege(college);
            member.setMemberCardId(123456);
            Integer id = memberService.save(member);
            LOGGER.info(JSON.toJSONString(id));
        }
    
        //查询关联表中的数据
        @Test
        public void findAll() {
            List<Member> members = memberService.findAll();
            for (Member member : members) {
                Iterator<Club> it = member.getClub().iterator();
                while(it.hasNext()){
                    Club club = it.next();
                    System.out.println(club.getClubIntroction());
                }
            }
        }
    
        @Test
        public void findAlls() {
            Page page = new Page();
            page.setCurrentPage(1);
            page.setTotalNumber(memberService.count());
            List<Member> members = memberService.findAll(page);
            for (Member member : members) {
                System.out.println(member.getMemberClass());
            }
        }
    
        @Test
        public void delete() {
            memberService.delete(11);
        }
    }

使用的maven管理个人使用通过 仅作参考