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对象导航查询

对象图导航检索方式是根据已经加载的对象，导航到他的关联对象。它利用类与类之间的关系来检索对象。

准备表和数据

实体类

package pers.zhang.entity;/** * @author zhang * @date 2019/12/15 - 22:10 */import javax.persistence.*;import java.util.HashSet;import java.util.Set;/** *  1.实体类和表的映射关系 *      @Entity *      @Table *  2.类中属性和表中字段的映射关系 *      @Id *      @GeneratedValue *      @Colum */@Entity //声明实体类@Table(name="cst_customer") //建立实体类和表的映射关系public class Customer {
       @Id//声明当前私有属性为主键    @GeneratedValue(strategy= GenerationType.IDENTITY) //配置主键的生成策略    @Column(name="cust_id") //指定和表中cust_id字段的映射关系    private Long custId;    @Column(name="cust_name") //指定和表中cust_name字段的映射关系    private String custName;    @Column(name="cust_source")//指定和表中cust_source字段的映射关系    private String custSource;    @Column(name="cust_industry")//指定和表中cust_industry字段的映射关系    private String custIndustry;    @Column(name="cust_level")//指定和表中cust_level字段的映射关系    private String custLevel;    @Column(name="cust_address")//指定和表中cust_address字段的映射关系    private String custAddress;    @Column(name="cust_phone")//指定和表中cust_phone字段的映射关系    private String custPhone;    //配置客户和联系人之间的关系（一对多）    /*        1.声明关系：            配置一对多关系：@OneToMany：targetEntity（对方对象的字节码）        2.配置外键（中间表）            name:外键字段的名称            referencedColumnName：参照的主表的主键字段名称        在客户实体类上（一的一方）添加了外键的配置，所以对于客户而言，也具备了维护外键的作用        实际情况下，只需要一方维护关系即可            mappedBy表示：放弃外键维护，由对方维护，取值为对方配置关系的属性名称        级联：cascade            CascadeType.ALL:所有                        MERGE:更新                        PERSIST：保存                        REMOVE：删除        fetch:配置关联对象的加载方式            EAGER：立即加载            LAZY：延迟加载     *///    @OneToMany(targetEntity = LinkMan.class)//    @JoinColumn(name = "lkm_cust_id", referencedColumnName = "cust_id")    @OneToMany(mappedBy = "customer", cascade = CascadeType.ALL, fetch = FetchType.LAZY)    private Set
   
     linkMans = new HashSet<>();    public Set
    
      getLinkMans() {
           return linkMans;    }    public void setLinkMans(Set
     
       linkMans) {
           this.linkMans = linkMans;    }    public Long getCustId() {
           return custId;    }    public void setCustId(Long custId) {
           this.custId = custId;    }    public String getCustName() {
           return custName;    }    public void setCustName(String custName) {
           this.custName = custName;    }    public String getCustSource() {
           return custSource;    }    public void setCustSource(String custSource) {
           this.custSource = custSource;    }    public String getCustIndustry() {
           return custIndustry;    }    public void setCustIndustry(String custIndustry) {
           this.custIndustry = custIndustry;    }    public String getCustLevel() {
           return custLevel;    }    public void setCustLevel(String custLevel) {
           this.custLevel = custLevel;    }    public String getCustAddress() {
           return custAddress;    }    public void setCustAddress(String custAddress) {
           this.custAddress = custAddress;    }    public String getCustPhone() {
           return custPhone;    }    public void setCustPhone(String custPhone) {
           this.custPhone = custPhone;    }    @Override    public String toString() {
           return "Customer{" +                "custId=" + custId +                ", custName='" + custName + '\'' +                ", custSource='" + custSource + '\'' +                ", custIndustry='" + custIndustry + '\'' +                ", custLevel='" + custLevel + '\'' +                ", custAddress='" + custAddress + '\'' +                ", custPhone='" + custPhone + '\'' +                '}';    }}
     
    
   

package pers.zhang.entity;import org.springframework.test.context.ContextConfiguration;import sun.awt.SunHints;import javax.naming.Name;import javax.persistence.*;/** * @author zhang * @date 2019/12/17 - 20:23 */@Entity@Table(name = "cst_linkman")public class LinkMan {
       @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    @Column(name = "lkm_id")    private Long lkmId;//联系人编号    @Column(name = "lkm_name")    private String lkmName;//联系人姓名    @Column(name = "lkm_gender")    private String lkmGender;//联系人性别    @Column(name = "lkm_phone")    private String lkmPhone;//联系人办公电话    @Column(name = "lkm_mobile")    private String lkmMobile;//联系人手机    @Column(name = "lkm_email")    private String lkmEmail;//联系人E-mail    @Column(name = "lkm_position")    private String lkmPosition;//联系人地址    @Column(name = "lkm_memo")    private String lkmMemo;//联系人备注    //配置联系人到客户的多对一关系    /*        @ManyToOne：配置多对一关系            targetEntity：对方的实体类额字节码        @JoinColumn：配置外键（中间表）            name:外键字段名            referencedColumnName：外键引用的主表主键字段名     */    @ManyToOne(targetEntity = Customer.class)    @JoinColumn(name = "lkm_cust_id", referencedColumnName = "cust_id")    private Customer customer;    public Customer getCustomer() {
           return customer;    }    public void setCustomer(Customer customer) {
           this.customer = customer;    }    public Long getLkmId() {
           return lkmId;    }    public void setLkmId(Long lkmId) {
           this.lkmId = lkmId;    }    public String getLkmName() {
           return lkmName;    }    public void setLkmName(String lkmName) {
           this.lkmName = lkmName;    }    public String getLkmGender() {
           return lkmGender;    }    public void setLkmGender(String lkmGender) {
           this.lkmGender = lkmGender;    }    public String getLkmPhone() {
           return lkmPhone;    }    public void setLkmPhone(String lkmPhone) {
           this.lkmPhone = lkmPhone;    }    public String getLkmMobile() {
           return lkmMobile;    }    public void setLkmMobile(String lkmMobile) {
           this.lkmMobile = lkmMobile;    }    public String getLkmEmail() {
           return lkmEmail;    }    public void setLkmEmail(String lkmEmail) {
           this.lkmEmail = lkmEmail;    }    public String getLkmPosition() {
           return lkmPosition;    }    public void setLkmPosition(String lkmPosition) {
           this.lkmPosition = lkmPosition;    }    public String getLkmMemo() {
           return lkmMemo;    }    public void setLkmMemo(String lkmMemo) {
           this.lkmMemo = lkmMemo;    }    @Override    public String toString() {
           return "LinkMan{" +                "lkmId=" + lkmId +                ", lkmName='" + lkmName + '\'' +                ", lkmGender='" + lkmGender + '\'' +                ", lkmPhone='" + lkmPhone + '\'' +                ", lkmMobile='" + lkmMobile + '\'' +                ", lkmEmail='" + lkmEmail + '\'' +                ", lkmPosition='" + lkmPosition + '\'' +                ", lkmMemo='" + lkmMemo + '\'' +                '}';    }}

Dao接口

public interface LinkManDao extends JpaRepository
   
    , JpaSpecificationExecutor
    
      {
   }
    
   

public interface CustomerDao extends JpaRepository
   
    , JpaSpecificationExecutor
    
      {
   }
    
   

测试类

package pers.zhang;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 org.springframework.transaction.annotation.Transactional;import pers.zhang.dao.CustomerDao;import pers.zhang.dao.LinkManDao;import pers.zhang.entity.Customer;import pers.zhang.entity.LinkMan;import java.util.Set;/** * @author zhang * @date 2019/12/17 - 23:25 */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext.xml")public class QueryByObjectTest {
       @Autowired    private CustomerDao customerDao;    @Autowired    private LinkManDao linkManDao;    /*        对象导航查询：查询一个对象的时候，通过此对象查询所有关联对象            默认使用的是延迟加载的形式查询的                调用get方法并不会立即发送查询，而是在使用关联对象的时候才会查询            如果不像使用延迟加载：                修改配置：fetch，需要配置到多表映射关系的注解上（OneToMany、ManyToMany、OneToOne）     */    @Test    @Transactional//解决no session问题    public void testQuery1(){
           Customer customer = customerDao.getOne(10L);        //对象导航查询，此客户下的所有联系人        Set
   
     linkMans = customer.getLinkMans();        for(LinkMan l : linkMans)            System.out.println(l);        /*            Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_address as cust_add2_0_0_, customer0_.cust_industry as cust_ind3_0_0_, customer0_.cust_level as cust_lev4_0_0_, customer0_.cust_name as cust_nam5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_source as cust_sou7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?            Hibernate: select linkmans0_.lkm_cust_id as lkm_cust9_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_cust_id as lkm_cust9_1_1_, linkmans0_.lkm_email as lkm_emai2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_memo as lkm_memo4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_name as lkm_name6_1_1_, linkmans0_.lkm_phone as lkm_phon7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=?            LinkMan{lkmId=3, lkmName='二狗', lkmGender='null', lkmPhone='null', lkmMobile='null', lkmEmail='null', lkmPosition='null', lkmMemo='null'}            LinkMan{lkmId=1, lkmName='小李', lkmGender='null', lkmPhone='null', lkmMobile='null', lkmEmail='null', lkmPosition='null', lkmMemo='null'}         */    }    /*        对象导航查询：查询一个对象的时候，通过此对象查询所有关联对象     */    @Test    @Transactional//解决no session问题    public void testQuery2(){
           Customer customer = customerDao.getOne(10L);        //对象导航查询，此客户下的所有联系人        Set
    
      linkMans = customer.getLinkMans();        for(LinkMan l : linkMans)            System.out.println(l);        /*            Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_address as cust_add2_0_0_, customer0_.cust_industry as cust_ind3_0_0_, customer0_.cust_level as cust_lev4_0_0_, customer0_.cust_name as cust_nam5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_source as cust_sou7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?            Hibernate: select linkmans0_.lkm_cust_id as lkm_cust9_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_cust_id as lkm_cust9_1_1_, linkmans0_.lkm_email as lkm_emai2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_memo as lkm_memo4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_name as lkm_name6_1_1_, linkmans0_.lkm_phone as lkm_phon7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=?            LinkMan{lkmId=3, lkmName='二狗', lkmGender='null', lkmPhone='null', lkmMobile='null', lkmEmail='null', lkmPosition='null', lkmMemo='null'}            LinkMan{lkmId=1, lkmName='小李', lkmGender='null', lkmPhone='null', lkmMobile='null', lkmEmail='null', lkmPosition='null', lkmMemo='null'}         */    }    /*        从多的一方查询：从联系人导航查询他所属客户            默认为立即加载        本质为：            从一方查询多方				* 默认：使用延迟加载（****）			从多方查询一方				* 默认：使用立即加载     */    @Test    @Transactional//解决no session问题    public void testQuery3(){
           LinkMan linkMan = linkManDao.getOne(2l);        //对象导航查询所属客户        Customer customer = linkMan.getCustomer();        System.out.println(customer);        /*            Hibernate: select linkman0_.lkm_id as lkm_id1_1_0_, linkman0_.lkm_cust_id as lkm_cust9_1_0_, linkman0_.lkm_email as lkm_emai2_1_0_, linkman0_.lkm_gender as lkm_gend3_1_0_, linkman0_.lkm_memo as lkm_memo4_1_0_, linkman0_.lkm_mobile as lkm_mobi5_1_0_, linkman0_.lkm_name as lkm_name6_1_0_, linkman0_.lkm_phone as lkm_phon7_1_0_, linkman0_.lkm_position as lkm_posi8_1_0_, customer1_.cust_id as cust_id1_0_1_, customer1_.cust_address as cust_add2_0_1_, customer1_.cust_industry as cust_ind3_0_1_, customer1_.cust_level as cust_lev4_0_1_, customer1_.cust_name as cust_nam5_0_1_, customer1_.cust_phone as cust_pho6_0_1_, customer1_.cust_source as cust_sou7_0_1_ from cst_linkman linkman0_ left outer join cst_customer customer1_ on linkman0_.lkm_cust_id=customer1_.cust_id where linkman0_.lkm_id=?            Customer{custId=11, custName='育碧', custSource='null', custIndustry='null', custLevel='null', custAddress='null', custPhone='null'}         */    }}
    
   

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