Java-EE輕量級(jí)框架應(yīng)用開發(fā) Hibernate的關(guān)聯(lián)映射

Java-EE輕量級(jí)框架應(yīng)用開發(fā)第6章-

Hibernate的關(guān)聯(lián)映射本章要點(diǎn)·多對(duì)一映射·一對(duì)多映射·一對(duì)一映射·多對(duì)多映射·雙向映射·Hibernate的主要目的就是Java程序員可以隨心所欲的使用對(duì)象編程思維來(lái)操縱數(shù)據(jù)庫(kù)一些數(shù)據(jù)庫(kù)表的關(guān)系應(yīng)該可以通過(guò)hibernate實(shí)現(xiàn)，比方在數(shù)據(jù)庫(kù)中常用到的主外鍵關(guān)系；還有一些跟主外鍵有關(guān)的設(shè)置，比方主鍵的信息被刪除，外鍵關(guān)聯(lián)的信息也要?jiǎng)h除等等如果把表抽象為實(shí)體類，這些關(guān)系可以抽象為實(shí)體類之間的一對(duì)一、多對(duì)一、一對(duì)多、多對(duì)多等關(guān)系。在Hibernate正確的配置這些關(guān)系以后，

Hibernate能夠處理這些復(fù)雜的關(guān)系，提高了開發(fā)的效率多對(duì)一映射配置如果規(guī)定一個(gè)客戶〔Customer〕可以建立多個(gè)訂單〔

Order〕，一個(gè)訂單只屬于一個(gè)顧客，這就是一個(gè)多對(duì)一關(guān)聯(lián)從Order到Customer的多對(duì)一單向關(guān)聯(lián)需要在Order類中定義一個(gè)Customer屬性，而在Customer類中無(wú)需定義存放Order對(duì)象的集合屬性關(guān)系數(shù)據(jù)模型Order表中的customer_id參照customer表的主鍵id·通過(guò)在映射文件中的many-to-one元素，可以定義持久化類間的多對(duì)一的關(guān)聯(lián)，這種關(guān)系模型實(shí)際上是一個(gè)對(duì)象引用<many-to-one①②③④⑥⑥name="propertyName"column="column_name"class="ClassName"cascade="all|none|save-update|delete"outer-join="true|false|auto"update="true|false"insert="true|false"property-ref="propertyNameFromAssociatedClass"access="field|property|ClassName"⑦⑧/>說(shuō)明①name：屬性名②column〔可選〕：字段名③class〔可選，默認(rèn)是通過(guò)反射得到屬性類型〕：關(guān)聯(lián)的類的名字④cascade〔級(jí)聯(lián)〕〔可選〕：指明哪些操作會(huì)從父對(duì)象級(jí)聯(lián)到關(guān)聯(lián)的對(duì)象，cascade屬性允許以下值none：:在保存,更新或刪除當(dāng)前對(duì)象時(shí),忽略其他關(guān)聯(lián)的對(duì)象,它是cascade屬性的默認(rèn)值save-update：當(dāng)通過(guò)Session的save(),update()以及

saveOrUpdate()方法來(lái)保存或更新當(dāng)時(shí)對(duì)象時(shí),級(jí)聯(lián)保存所有關(guān)聯(lián)的新建的臨時(shí)對(duì)象,并且級(jí)聯(lián)更新所有關(guān)聯(lián)的游離對(duì)象delete：當(dāng)通過(guò)Session的delete()方法刪除當(dāng)前對(duì)象時(shí),級(jí)聯(lián)刪除所有關(guān)聯(lián)的對(duì)象all：包含save-update以及delete的行為.此外,對(duì)當(dāng)前對(duì)象執(zhí)行

outer-join〔外連接〕〔可選，默認(rèn)為自動(dòng)〕：當(dāng)設(shè)置

hibernate.use_outer_join時(shí)，對(duì)這個(gè)關(guān)聯(lián)允許外連接抓取。outer-join參數(shù)允以下3個(gè)不同值auto〔默認(rèn)〕：如果被關(guān)聯(lián)的對(duì)象沒(méi)有代理〔Proxy〕，使用外連接抓取關(guān)聯(lián)〔對(duì)象〕true：一直使用外連接來(lái)抓取關(guān)聯(lián)false：永遠(yuǎn)不使用外連接來(lái)抓取關(guān)聯(lián)⑥update、insert〔可選，默認(rèn)為true〕：指定對(duì)應(yīng)的字段是否在用于

UPDATE和/或INSERT的SQL語(yǔ)句中包含。如果二者都是false，那么這是一

個(gè)純粹的“衍生〔Derived〕〞關(guān)聯(lián)，它的值是通過(guò)映射到同一個(gè)〔或多個(gè)〕字段的某些其他屬性得到的，或者通過(guò)Trigger〔觸發(fā)器〕，或者其他程序

⑦property-ref：〔可選〕：指定關(guān)聯(lián)類的一個(gè)屬性，這個(gè)屬性將會(huì)和本外鍵相對(duì)應(yīng)。如果沒(méi)有指定，會(huì)使用對(duì)方關(guān)聯(lián)類的主鍵⑧access〔可選，默認(rèn)是property〕：Hibernate用來(lái)訪問(wèn)屬性的策略Hibernate設(shè)置多對(duì)一關(guān)聯(lián)·以O(shè)rder和Customer之間的多對(duì)一關(guān)聯(lián)為例·

Customer.java·

Order.javaprivate

String

name;return

id;}this.id

=

id;return

name;public

void

setName(String

name)

{

=

name;}public

class

Order

{private

Integer

id;private

String

orderNumber;private

Double

price;private

Customer

customer;//增加了“1〞方的對(duì)象為自己的屬性public

Inte

er

getId()

{publpiucblcilcasvsoiCdusteotmIedr(I{nteger

id)

{privtahties.Iindte=giedr;id;}public

String

getOrdepruNbulmibcerI(n)te{ger

getId()

{publtihcisv.ooirddseertNIudm(bIenrt=egoerrdeirdN)u{mber;}publriectuSrtnripnrgicge;tName()

{}}public

Cu}stomer

getCustomer()

{return

customer;}public

void

setCustomer(Customer

customer)

{this.customer

=

customer;}}<hibernate-mapping><class

name="entirteyt.uOrndeird";

table="Order

">}<generator

class="increment"

/></id><colurmentunranmeo=r"doerdNeurm_bnearm;e"

length="20"></column></p}roperty><!--manpyu-btloi-conveo關(guān)id聯(lián)se-t-O>rderNumber(String

orderNumber){<many-to-one

name="customer"column="customer_id"

class="entity.Customer"not-null="true">

public

Do}uble

getPrice()

{</many-to-one></clapsusb>lic

vo}id

setPrice(Double

price)

{</hibernate-mappingt>his.price

=

price;測(cè)試多對(duì)一映射·先保存訂單，再保存客戶public

void

insert(){·

運(yùn)行后在控制Se臺(tái)ssi下on

se會(huì)ssi輸on=s出essi以onFa下cto語(yǔ)ry.o句penSession();Transaction

transaction=session.beginTransaction();Customer

customer=new

Customer();Hibernate:insert

into

scustomer.sredrO.poh (ectuNsatmoem(e"r張_i三d,"o)r;derNumber,price)values(?,?,?)Hibernate:

insert

into

shop.rucedrO Osrtdoemre=rn(nawe

Omred)evalues;)(r (?)Order.setOrderNumber("0001");Hibernate:update

shop.O/r/d關(guān)er聯(lián)se訂t

單cu和st客ome戶r_id=?,orderNumber=?,price=?where

id=?Order.setCustomer(customer);//保存訂單

session.save(Order);//保存客戶session.save(customer);transaction

mit();session.close();}·先保存客戶，再保存訂單public

void

insert(){Order

Order=new

Order();Order.setOrderNumber("001");//關(guān)聯(lián)訂單和客戶Order.setCustomer(customer);//保存客戶

session.save(customer);//保存訂單session.save(Order);transaction

mit();session.close();}·

運(yùn)行后在控S制essi臺(tái)on

s下essi會(huì)on=輸sess出ionF以acto下ry.語(yǔ)open句Session();Transaction

transaction=session.beginTransaction();Hibernate:

insert

into

shCuosp.tcoumsetrocmuesrt(omnearm=en)evwaClusetso(m?e)r();Hibernate:insert

into

schuospt.oOmredre.rs(ectuNsatmoem(e"r張_i三d,"o)r;derNumber,price)values(?,?,?)·保存訂單，不保存客戶·在代碼中注釋掉session.save(customer),只保存訂單，不保存客戶public

void

insert(){·

運(yùn)行后在控S制essi臺(tái)on

s下essi會(huì)on=s輸essi出onF以acto下ry.o語(yǔ)penS句ess,io可n();以看到HibernateTransaction

transaction=session.beginTransaction();對(duì)這次數(shù)據(jù)操Cus作tome的r

cu執(zhí)stom行er=n流ew

C程ustomer();customer.setName("張三");//關(guān)聯(lián)訂單和客戶//保存客戶·當(dāng)hibernatOerd持er.s久etOr化derN一umb個(gè)er("臨o_00時(shí)1");對(duì)象時(shí)，在默認(rèn)情況下，它不會(huì)自動(dòng)持久Ord化er.s所etCu關(guān)sto聯(lián)mer(的cust其omer他);臨時(shí)對(duì)象，會(huì)拋出

TransientOb/j/seescsitonE.sxavcee(cpusttoimeor)n;//保存訂單session.save(Order);transaction

mit();session.close();}Hibernate:

insert

into

shOorpd.eOrrOdredre(rc=unsetwoOmredre_ri(d),;orderNumber,

price)

values

(?,

?,

?)·如果設(shè)定many-to-one元素的cascade屬性為save-update的話，可實(shí)現(xiàn)自動(dòng)持久化所關(guān)聯(lián)的對(duì)象，對(duì)剛剛order的映射文件里的many-to-one進(jìn)行修改·再次運(yùn)行前面的代碼，運(yùn)行后在控制臺(tái)下會(huì)輸出以下語(yǔ)句<many-to-one

name="customer"

column="CUSTOMER_ID"

class="entity.Customer"

not-null="true"

cascade="save-update"></many-to-one>Hibernate:

insert

into

shop.customer

(name)

values

(?)·H可iber以nate:看inse到rt

i這nto

s次hop.O會(huì)rder自(cus動(dòng)tome執(zhí)r_id,行orde了rNum保ber,存pricce)uvasluteso(?m,?e,r?)的操作·多對(duì)一映射·一對(duì)多映射·一對(duì)一映射·多對(duì)多映射·雙向映射一對(duì)多映射配置·

Hibernate提供了一對(duì)多關(guān)系的標(biāo)簽<one-to-many>，一對(duì)多是在一的一端維護(hù)多的一端·

一對(duì)多關(guān)系的對(duì)象模型在日常生活中也經(jīng)?？吹剑粋€(gè)客戶〔Customer〕可以有多張訂單〔Order〕，所以客戶和訂單的關(guān)系也是一對(duì)多的關(guān)系·

在進(jìn)行關(guān)系映射時(shí)需要在一的一端添加對(duì)應(yīng)的set屬性，并在它的配置文件中添加set標(biāo)簽，在set標(biāo)簽中配置相應(yīng)的<one-to-many>標(biāo)簽在Hibernate設(shè)置一對(duì)多關(guān)聯(lián)set屬性，但是只是說(shuō)明了延性配置對(duì)應(yīng)的對(duì)象，屬return

Order;·以O(shè)rder和Customer之間的一對(duì)多關(guān)聯(lián)為例<phuibleircncaltaes-smaCpupsitnogm>er

{·<claCsus

nsamtper=oi"vmeanteteirtIyn..tCejugseatrovimdea;r"

table="customer"

catalog="demotest">private

String

name;<generpartiovratcelaSsest=O"ridnecr;ement"

/></?id>Customerpu對(duì)bli象c

Set中g(shù)et使Orde用r()了{(lán)遲<}加colu載mn

n的ame=屬"nam性e"l，engt并h="2沒(méi)0">有</co為lumn屬></properptuyb>lic

void

setOrder(Set

Order)

{<set性nam的e="O對(duì)rder象es"t是ihnivse.要rOsred=在e"rt=r映uOer"d>e射r;文件中來(lái)配置的，需要添加set<key>}<標(biāo)colp簽umbnlin，camIen并=t"ecgue在srtgoemsteIred_(it)d標(biāo)"{/>簽中添加<one-to-many>標(biāo)簽</key>

return

id;<one-t}o-many

class="entity.Order"

/></set>

public

void

setId(Integer

id)

{</class>

this.id

=

id;</hibernate-}mapping>public

String

getName()

{return

name;}public

void

setName(String

name)

{

=

name;}}測(cè)試多對(duì)一映射·寫入數(shù)據(jù)加Order對(duì)象時(shí)應(yīng)該使用p·ublic寫void入sav數(shù)e(){據(jù)需要注意的是一對(duì)多的關(guān)系，所以在添加的Session

session=sessionFactory.openSession();時(shí)候需要添加Tran多sact個(gè)ionOtrrandsaectri類on=s，essi另on.b外egi由nTra于nsac在tionC()u;stomer中添Order

order1=new

Order();加了對(duì)應(yīng)的soredetr1屬.set性O(shè)rd，erNu所mber以("00在1")添;session.save(order1);HashSet來(lái)添Or加der

，orde這r2=n樣ew

O即rder可();實(shí)現(xiàn)一對(duì)多的關(guān)系order2.setOrderNumber("002");session.save(order2);·

運(yùn)行測(cè)試用Cu例stom，er

c生usto成mer=的new對(duì)Cust應(yīng)omer的();SQL語(yǔ)句customer.setName("張三");

Set

Order=new

HashSet();Order.add(order1);Order.add(order2);customer.setOrderes(Order);session.save(customer);transaction

mit();session.close();}Hibernate:

insert

into

shop.Order

(customer_id,

orderNumber,

price)

values

(?,

?,

?)Hibernate:

insert

into

shop.Order

(customer_id,

orderNumber,

price)

values

(?,

?,

?)Hibernate:

insert

into

shop.customer

(name)

values

(?)·讀取數(shù)據(jù)有加載的對(duì)象都添加不很高public

void

load(){·

寫入Se操ssio作n

se相ssio對(duì)n=s簡(jiǎn)essi單onFa，ctor只y.o需penS要essi把on()所;Transaction

transaction=session.beginTransaction();到Transient/狀/獲態(tài)取主下鍵為，1的運(yùn)客戶行信息相應(yīng)的方法就可以插入內(nèi)容，Customer

customer

=

(Customer)

session.load(Customer.class,1);但是對(duì)/應(yīng)/打的印客讀戶信取息操作就會(huì)稍微復(fù)雜點(diǎn)，因?yàn)樾枰@取所有的訂//設(shè)單置訂對(duì)單象集合，，通所過(guò)客以戶這加載種訂單一集合對(duì)多的關(guān)系效率并Set

Order=customer.getOrder();//迭代集合，打印集合中訂單的信息for(Iterator

iter=Order.iterator();iter.hasNext();){·

生成的相}應(yīng)的語(yǔ)句及信息transaction

mit();session.close();H}ibernate:

select

customer0_.id

as

id0_0_,

customer0_.name

as

name0_0_

from

shop.customercustomer0_

where

customer0_.id=?=張三Hibernate:

select

Orderes0_.customer_id

as

customer2_1_,

Orderes0_.id

as

id1_,

Orderes0_.id

as

id1_0_,Orderes0_.customer_id

as

customer2_1_0_,

Orderes0_.orderNumber

as

orderNum3_1_0_,Orderes0_.price

as

price1_0_

from

shop.Order

Orderes0_

where

Orderes0_.customer_id=?order.orderNumber=0001·一對(duì)多的關(guān)系也是經(jīng)常用到的，但是這種關(guān)系在加載時(shí)效率會(huì)不高，因?yàn)樾枰S護(hù)的數(shù)據(jù)較多，所以不建議使用一對(duì)多的關(guān)系，可以考慮多對(duì)一的關(guān)系，這樣在加載時(shí)其實(shí)是一種一對(duì)一的關(guān)系，加載的效率較高，關(guān)系和對(duì)象模型得到了優(yōu)化·多對(duì)一映射·一對(duì)多映射·一對(duì)一映射·多對(duì)多映射·雙向映射一對(duì)一映射配置·如果規(guī)定一個(gè)客戶〔Customer〕只能建立一個(gè)訂單〔Order〕，一個(gè)Order只屬于一個(gè)Customer，這就是一個(gè)一對(duì)一關(guān)聯(lián)從Order到Customer的一對(duì)一單向關(guān)聯(lián)需要在Order類中定義一個(gè)Customer屬性，而在Customer類中無(wú)需定義存放Order對(duì)象的集合屬性關(guān)系數(shù)據(jù)模型Order表中的customer_id參照

customer表的主鍵id·通過(guò)在映射文件中的<one-to-one>元素，可以定義持久化類之間的一對(duì)一的關(guān)聯(lián)，這種關(guān)系模型實(shí)際上是一個(gè)對(duì)象引用<one-to-one①②③④name="propertyName"class="ClassName"cascade="all|none|save-update|delete"constrained="true|false"outer-join="true|false|auto"property-ref="propertyNameFromAssociatedClass"access="field|property|ClassName"⑥⑦/>說(shuō)明·

①name：屬性的名字②class〔可選-默認(rèn)是通過(guò)反射得到的屬性類型〕：被關(guān)聯(lián)的類的名字③cascade〔級(jí)聯(lián)〕〔可選〕說(shuō)明操作是否從父對(duì)象級(jí)聯(lián)到被關(guān)聯(lián)的對(duì)象④constrained〔約束〕〔可選〕說(shuō)明該類對(duì)應(yīng)的表對(duì)應(yīng)的數(shù)據(jù)庫(kù)表，和被關(guān)聯(lián)的對(duì)象所對(duì)應(yīng)的數(shù)據(jù)庫(kù)表之間，通過(guò)一個(gè)外鍵引用對(duì)主鍵進(jìn)行約束。這個(gè)選項(xiàng)影響save()和delete()在級(jí)聯(lián)執(zhí)行時(shí)的先后順序

outer-join〔外連接〕〔可選，默認(rèn)為自動(dòng)〕：當(dāng)設(shè)置

hibernate.use_outer_join的時(shí)候，對(duì)這個(gè)關(guān)聯(lián)允許外連接抓取⑥property-ref：〔可選〕指定關(guān)聯(lián)類的一個(gè)屬性，這個(gè)屬性將會(huì)和本外相對(duì)應(yīng)。如果沒(méi)有指定，會(huì)使用對(duì)方關(guān)聯(lián)類的主鍵⑦access〔可選，默認(rèn)是property〕：Hibernate用來(lái)訪問(wèn)屬性的策略Hibernate設(shè)置一對(duì)一關(guān)聯(lián)public

class

Order

{private

Integer

id;

private

String

orderNumber;}public

String

getOrderNumber()

{this.price

=

price;}private

String

name;public

voriedtsuertnIodr(dIenrtNeugmebreird;)

{·以CuprsivtatoeDmoueblre

p和riceO;rder之間的一對(duì)一關(guān)聯(lián)為例private

Customer

customer;//增加了另外一方的對(duì)象為自己的屬性<phuibleircnacltpeau-sbsmlaCipucpsiItnogtm>egre{r

getId()

{<·classCnaumesp=r"tievnoatmieteIyrn.ertOteru.gdrenjri"aidt;v;abale="Order"

catalog="shop"><coplubmlnicnavmoei=d"siedt"I/pd>u(bIlnitcegIenrteigde)r{getId()

{·<geOnrerdateorrc.lajstsha=i"svrn.eaiatduir=vnei"id>d;<;/generator></id>}

}<co}lumn

name="ordetrhNiusm.biedr"=liedn;gth="10"

/></propuebrl}tiyc>void

setOrderNumber(String

orderNumber)

{public

Strhinsg.goertdNeramNeu(m)be{r

=

orderNumber;<co}lumn

name="pricree"tpurencniasmieo;n="22"

scale="0"

/></propuebrl}tiyc>Double

getPrice()

{<!—order到cpusbtloimcerv的oried一tus對(duì)rent一Npar映miec(射eS;t-r-i>ng

name){<one-}to-one

name="cutshtiosm.enra"mcel=asnsa=m"ee;ntity.Customer"constrained="true"></onep-utbol}-iocnveo>id

setPrice(Double

price)

{}</class></hibernaptueb-lmiacppCiunsgt>omer

getCustomer()

{return

customer;}public

void

setCustomer(Customer

customer)

{this.customer

=

customer;}}測(cè)試一對(duì)一映射,可以看到Hibernate對(duì)·先保存訂單，再保存客戶public

void

insert(){·運(yùn)行后在控Ses制sion臺(tái)sessi下on=s會(huì)essi輸onFac出tory以.ope下nSess語(yǔ)ion(句);Transaction

transaction=session.beginTransaction();Customer

customer=new

Customer();custo這mer.次setN數(shù)ame("據(jù)張三操");作的執(zhí)行流程Order

Order=new

Order();Hibernate:insert

into

sOhrodpe.rO.rsdetrO(rdoerrdNeurmNbuemrb(e"r0,0p0r1i"c)e;)values(?,?)

Hibernate:insert

into

s/h/o關(guān)p.聯(lián)cu訂st單om和er客(n戶ame)values(?)Order.setCustomer(customer);//保存訂單

session.save(Order);//保存客戶session.save(customer);transaction

mit();session.close();}·多對(duì)一映射·一對(duì)多映射·一對(duì)一映射·多對(duì)多映射·雙向映射多對(duì)多映射配置學(xué)生〔Student〕和老師〔Teacher〕就是多對(duì)多的關(guān)系。一個(gè)Student有多個(gè)老師，一個(gè)Teacher教多個(gè)學(xué)生多對(duì)多映射引入兩邊的主鍵作為外鍵持久化對(duì)象之間多對(duì)多的關(guān)聯(lián)關(guān)系是通過(guò)<many-to-many>元素定義的<many-to-manycolumn="column_name"①class="ClassName"②outer-join="true|false|auto"③/>說(shuō)明·①column〔必需〕：這個(gè)元素的外鍵關(guān)鍵字段名②class〔必需〕：關(guān)聯(lián)類的名稱③outer-join〔可選，默認(rèn)為auto〕：在Hibernate系統(tǒng)參數(shù)中hibernate.use_outer_join被翻開的情況下，該參數(shù)用來(lái)允許使用outer

join來(lái)載入此集合的數(shù)據(jù)Hibernate設(shè)置多對(duì)多關(guān)聯(lián)<generator

class="native"></generator></id>}·以Student和Teacher之間的一對(duì)一關(guān)聯(lián)為例p<uhbiblblieicrncaltaes-smSTatepupadciehnegtr>

{<hibern·ate-mp<pSarcpiltpvaviasuntsgedn>IaIenmtene=g"tern實(shí)tidt;體y.Te類acher"table="teacher">private

Str<ricinlngagsnsamnmeae;m;e=<"iedntniatmye.=S"tiud"etnytp"et=a"bilnet=">student">

privateISnete<gSetrudtenatc>hesr<tiud;enatmse=n"eiwd<"HcatosylhpuSeme=nt"<niSantmtue"d=>e"nitd>"(>)<;/c/o/l增um加n>學(xué)生屬性·

pSubtliucdInetengetr

g映etId射(){文<cgeo件nleurmantnoarmec=l"asisd"=">n</actiolvue"mn><>/generator>r<re/etitudur>rn

id;·

pTubeliaccvohides<reste實(shí)Itd(n(IaI體nmntete=eg"g類esertruide)n{t{s"table="student_teacher"cascade="all">this.id

=

id;<key

column="teacher_id"></key>}

</—c!l配ass置>many-to-many--></hiber·nate-pTmuabeplpiaicncSgt>hriengrg映etNa射me()文{<ma件ny-to-many

class="entity.Student"column="student_id"></mraentyu-rtnon-namamamene;y;>}

</set>p<pu/ubcbliacscsv>oid

setName(String

name)

{</hibernate-mapping>

=

name;}publicISnete<gSetrudgentT>eagcehteSrtiud(e)nt{s()

{returntsetaucdhenrts;}public

void

setTSetaucdhenrtisd(SIent<eSgteurdetneta>chsetruide)nt{s)

{this.steuadcehnetrsid==stuedaecnhtesr;id;}}測(cè)試多對(duì)多映射·保存教師信息·解除學(xué)生跟老師的關(guān)系刪除學(xué)生、刪除老工解除public

void

save(){·

運(yùn)行測(cè)試S用essi例on

s，essi生on=成sess的ionF對(duì)acto應(yīng)ry.的openSSeQssLio語(yǔ)n()句;Transaction

transaction=session.beginTransaction();session.close();}ins

r

into

student_teacher

(t

ach

r_id,

student_id)

values

(?,

?)Hpiubelrincavtoei:dibnusielrdt(i)n{to

tetaecahcheerr(2n.asmet)Nvaamleu(e"s李(老?)師");Teacher

teacher=(T

acher)

s

ssion.get(Teacher.

lass,

2)

;師，因?yàn)槔蟬es師sio是n.sa關(guān)vet(rt系aenascah維cetri1護(hù)o)n;者mit(，);所以可以直接解除老師session.saves(etsesaicohne.rc2l)o;se();}與學(xué)生的關(guān)tra系nsa，ctio不n

m用it()手;Hibernate:

select

teach

rest0u_d.eindta.2

sedtN_am_e("te李c四e"r)0;s

i

4

0

, a

h

_.name

as

name4_0_

from

teacher

teacher0_

whereHibernate:

insert

into

steuadcenhte_rt2e.agcehteSrtu(dtenatcsh(e)r._aid,(student_2i);d)

values

(?,

?)pubHlibcervnoaitde:reimnosver(t)i{nto

teTaecahcherer(ntaemaec)hevra1l=unesw(T?e)acher();·Hi為bern老ate:師inse添rt

in加to

st一uedaecnh個(gè)etr(1n.asS學(xué)mets)Nsvai生amolenu(s"es王ss(老i?)o師n="s)e;ssionFactory.openSession();Hibernate:

insert

into

stTuedaecnhter(nteaTamrcea)hnevsra2lc=utneiesown(Tt?e)racnhsearc(t)i;on=session.beginTransaction();Hibernate:insert

into

stsutduednetn_tt1e.asTecehtaTeNcrahame(nerts(eta"eac張acthci三ehoren"_r)ti=;rd(a,Tnesatacuchdteirno)tns_=eisde)sisvoianol.nug.ebste(g?Ti,enaT?cr)haenrs.acltaisosn,()1;);Hibernate:

insert

into

stSutduednent_ttsetatucedhaecnrhte(2rt=.negeaewcthSetru_diedn,ts()(t)u;d.ernetm_oivde)(svtaulduenst()?;,

?)Htiebaecrhneart0e_:.idn=s?ert

into

stSutduednetn_ttsetasucedhseSesntrituo3(dn=te.nenuaetpcwdshSateturued_d(eitendnet,ta=(scnt)he;uewdrSe)tn;utd_eindt)(v)a;lues

(?,

?)Hibernate:select

studenstsu0d_e.nte3a.cshetrsN_taiumd

e(ans"t王t.es五aect"hN)ea;rm2e_(4"_趙1_六,s"t)u;dents0_.student_id

as

student1_1_,stu·dent1刪_.id除as

i學(xué)d2_0生_,st，teuadceh因entr1為_.gt.nerata學(xué)tmSnetsauacd生shtenirato.msn不g(e)2tm_.是Sa0itd_tu(dfd)(r關(guān)e;sontmtusds系(et)nu.dtae1維dn)d;t(_護(hù)steuadc者ehnetr)，s;tud所ents以0_

i需nner要joi先n

st手udentstudent1_

on

students0_.tsetaucdhenrt1_.igsde=tsSstiuodne.nctl1so_(s.e)i.(d)a;wdhde(sretusdteundte3n)t;s0_.teacher_id=?Hibern工ate:解}ins除ert

i老nto師stueda與cenhet學(xué)r(2n.agm生et)sSevt的suasldiueoen關(guān)nst.s(u(?聯(lián)p)d.atd，ed(tset然aucdhen后rt)1;)再;多H多ib·ern對(duì)at運(yùn)e:i多n行多ser測(cè)t

i性nt試o

sSt用能utdueden例tnt不(ns，taSmutedue)生S佳d佳nevtsna1slt成=iunsoet，nswu的s(dSe?etsn)ust對(duì)di數(shù)=數(shù)eo(nSt=t應(yīng)(su)ed;據(jù)se的snito)nsSF量e量aQscstLior語(yǔ)ny大.goep句te(nS時(shí)teusdseinot應(yīng)n.(c)l;as盡s盡,2);可能防防止使使用·多對(duì)一映射·一對(duì)多映射·一對(duì)一映射·多對(duì)多映射·雙向映射雙向一對(duì)多映射雙向一對(duì)多與雙向多對(duì)一是完全相同的兩種情形。雙向一對(duì)多需要在一的一端可以訪問(wèn)多的一端,反之依然從Order到Customer的多對(duì)一雙向關(guān)聯(lián)需要在

Order類中定義一個(gè)Customer屬性,還要在

Customer類中需定義存放Order對(duì)象的集合屬性Hibernate設(shè)置雙向多對(duì)一關(guān)聯(lián)·Order.java·

在Order中需要定義Customer屬性件中，使用<one-to-many>元素來(lái)映在Order的映射文件中，使用<many-to-one>元素來(lái)映射this.id

=

id;this.orderNumber

=

orderNumber;return

this.price;private

Integer

id;private

SCturstinomgenracmeus;tomer;

//定義Customer屬性private

StertiOnrgdoerdeesr=NunembweHra;shSet(0);//定義Order屬性purbivlaitceInDtoeugbeler

gpretiIcde;()

{·CustpuoblmiceInrte.grejertguaertnvItdah(i)s{.id;}

return

this.id;·

在}publCicuvsoitd

soemtIed