2.2, hibernate with annotations to achieve a one-to-many, many-to-many relationship

A, one -to-many relationship

1, in the previous log with the. XML configuration file project, and then add a package to the Lib directory first-hibernate-jpa-2.0-api-1.0.0.final.jar

2. Create a new COM.ST.BEAN4 package and add two classes containing annotations to the package:

A), DeptBean2 class:

 1 package com.st.bean4; 2 3 Import Java.util.HashSet; 4 Import Java.util.Set; 5 6 7 Import Javax.persistence.Column; 8 Import javax.persistence.Entity; 9 Import javax.persistence.generatedvalue;10 Import javax.persistence.id;11 import javax.persistence.joincolumn;12 Import javax.persistence.onetomany;13 import javax.persistence.table;14 import Org.hibernate.annotations.Cascade;                                               Import org.hibernate.annotations.cascadetype;17 Import org.hibernate.annotations.genericgenerator;18 @Entity Specify the entity class @Table (name= "DEPT")//name of the corresponding table @Generic                                               Generator (name= "GenID", strategy= "increment")//declaring a primary key generation strategy in public class DeptBean2 {@Id                                Specify primary key @GeneratedValue (generator= "GenID")//Set Primary key generation strategy @Column (name= "ID")                              Specifies the correspondence between the attributes in the class and the columns in the table. Id;27 @Column (name= "name")Specifies the corresponding relationship between a property in a class and a column in a table. name;29 3//Specify a one-to-many relationship in the list 1 @Cascade (Value={cascadetype.save_update})//Set Cascade relationship @JoinColumn (name= "dept_id")/ /Specifies the foreign key of the appearance corresponding to the primary key of this class. set<employeebean2> emp = new hashset<employeebean2> (); @Override35 p  Ublic String toString () {Deptbean return "id=" + ID + ", name=" + name + "]"; PNs}38 public Long getId () {id;40}41 public void setId (long id) {$ this.id = id;43}44 public String get     Name () {name;46}47 public void SetName (String name) {this.name = name;49}50 Public set<employeebean2> getemp () {emp;52}53 public void Setemp (Set<employeebean2&gt ; EMP) {this.emp = emp;55}56}

b), Employeebean class:

 1 package com.st.bean4; 2 3 Import Javax.persistence.Column; 4 Import javax.persistence.Entity; 5 Import Javax.persistence.GeneratedValue; 6 Import Javax.persistence.Id; 7 Import Javax.persistence.JoinColumn; 8 Import Javax.persistence.ManyToOne; 9 Import javax.persistence.table;10 Import org.hibernate.annotations.genericgenerator;12 @Entity//Specify an entity @Tabl E (name= "employee")//Specify the name of the table @GenericGenerator (name= "GenID", strategy= "increment")//Declare primary key generation policy-public class                EmployeeBean2 {@Id//Specify PRIMARY key @GeneratedValue (generator= "GenID") Set the primary key generation strategy @Column (name= "ID")//the corresponding relationship between a property in a class and a column name in a table. id;2 1 @Column (name= "name") of the private string name;23 @Column (name= "SEX") of the private string sex;25 @Column (NA Me= "JOB")-Private String job;27 @ManyToOne//Specify many-to-one relationship//Specify many-to-one relationship @JoinColumn (name= "DEP t_id ") 29//An employee corresponds to a department number, so there is no need to assemble the private DeptBean2 dept;         Note that this place does not have a new object, otherwise it will not run to public long getId () {return id;33}34 public void setId (long id) {35  This.id = id;36}37 public String getName () {# return name;39}40 public void SetName (string Name) {this.name = name;42}43 public String getsex () {sex;45-return,}46-public voi     D setsex (String sex) {This.sex = sex;48}49 public String getjob () {return job;51}52 public void Setjob (String job) {this.job = job;54}55 public DeptBean2 getdept () {# D ept;57}58 public void setdept (DeptBean2 dept) {$ this.dept = dept;60}61 @Override62 public String toString () {Employeebean [id= "+ ID +", name= "+ name +", sex= "+ sex64 +", j    ob= "+ Job +", dept= "+ Dept65 +"] "; 66 }67} 

3. The mapping of the above two classes is introduced in the Hibernate.cfg.xml file

1          <mapping class= "com.st.bean5.UserBean2"/>2          <mapping class= "com.st.bean5.RoleBean2"/>

4, add the corresponding test method in Beantest:

1     @Test 2 public     void Bean4test1 () {3         session session = Hibernatetools.opensession (); 4         Transaction Tran = Session.begintransaction (); 5         //First add a new data in dept, then associate a new data in employee 6         //deptbean2 dept = new DeptBean2 () 7         ///Read the data in dept first, And then on the basis of the reading is associated with a new data in employee 8         DeptBean2 dept = (DeptBean2) session.get (deptbean2.class,1l);//1l represents the primary key 9         EmployeeBean2 emp = new EmployeeBean2 (),         //dept.setname ("technical Department"),         emp.setname ("Chen Zejun")         ; Emp.setsex ("male"),         emp.setjob ("STM32"),         dept.getemp (). Add (EMP),         session.save (dept);         Confirm the submission of things         tran.commit ();     

　

Two, many-to-many relations

1. Create a new COM.ST.BEAN4 package and add two classes containing annotations to the package

A), UserBean2:

 1 package com.st.bean5; 2 Import Java.util.HashSet; 3 Import Java.util.Set; 4 5 Import Javax.persistence.Column; 6 Import javax.persistence.Entity; 7 Import Javax.persistence.GeneratedValue; 8 Import Javax.persistence.Id; 9 Import javax.persistence.joincolumn;10 import javax.persistence.jointable;11 import Javax.persistence.ManyToMany; Import javax.persistence.table;13 Import org.hibernate.annotations.cascade;15 Import                                                ORG.HIBERNATE.ANNOTATIONS.CASCADETYPE;16 Import org.hibernate.annotations.genericgenerator;17 @Entity Entity @Table (name= "T_user")//Table name @GenericGenerator (name=                                                "GenID", strategy= "increment")//declaring primary key generation strategy, public class UserBean2 {@Id                                 Specify primary key @GeneratedValue (generator= "GenID")//Set Primary key generation strategy @Column (name= "ID") Specifies the corresponding relationship between the properties of the class and the fields of the table. Id;26 @Column (name= "name") The private string name;28 @Column (name= "SEX") in private string sex;30 @ManyToMany Specify a many-to-many relationship @Cascade (value={cascadetype.save_update})//Set a cascade relationship of @JoinTable (name= "User_ro LE ",//Specify the third table joincolumns={@JoinColumn (name=" user_id ")},//This table corresponds to the foreign key of the intermediate table inversejoincolumns={@JoinColumn (name= "role_id")})//the corresponding relationship between the other table and the foreign key of the third table. Private Set<rolebea n2> role = new hashset<rolebean2> (); n Public long GetId () {PNS return id;38}39 public void S Etid (Long id) {this.id = id;41}42 public String getName () {for name;44,}45 Publi     c void SetName (string name) {this.name = name;47}48 public String getsex () {return sex;50 }51 public void Setsex (String sex) {this.sex = sex;53}54 public set<rolebean2> getrole () {return to role;}57 public void Setrole (set<rolebean2> role) {this.role = role;59}60 @Override61 Public String toString () {UserBean [id=] + ID + ", name=" + name + ", sex=" + sex63 + " , role= "+ role +"] "; 64}65}

b), Rolebean class:

 1 package com.st.bean5; 2 Import Java.util.HashSet; 3 4 Import Java.util.Set; 5 6 Import Javax.persistence.Column; 7 Import javax.persistence.Entity; 8 Import Javax.persistence.GeneratedValue; 9 Import javax.persistence.id;10 Import javax.persistence.joincolumn;11 import javax.persistence.jointable;12 Import JAVAX.PERSISTENCE.MANYTOMANY;13 Import javax.persistence.table;14 Import org.hibernate.annotations.cascade;16                                              Import org.hibernate.annotations.cascadetype;17 Import org.hibernate.annotations.genericgenerator;18 @Entity Entity @Table (name= "t_role")//Table name @GenericGenerator (NA                                              Me= "GenID", strategy= "increment")//Declaration primary key generation policy, public class RoleBean2 {@Id                                 Primary key @GeneratedValue (generator= "GenID")//Set Primary key generation strategy @Column (name= "ID") The correspondence between the attributes in the class and the fields of the table. Id;27 @Column (name= "POST")/PRIvate String post;//position @Column (name= "pay")-private int pay;        Salary @ManyToMany//Many-to-many relationship @Cascade (value={cascadetype.save_update}) Cascade Relationship @JoinTable (name= "User_role",//Intermediate table name joincolumns={@JoinColumn (name= "role_id")},//The foreign key correspondence between this table and the intermediate table inversejoincolumns={@JoinColumn (name= "user_id")})//Another table corresponds to the foreign key of the intermediate table 3  6 private set<userbean2> user = new hashset<userbean2> (); PNs public Long getId ()         id;40}41 public void setId (long id) {$ this.id = id;43}44 public String getpost () {45 return post;46}47 public void Setpost (String post) {$ this.post = post;49}50 public int Getpay ( {pay;52}53 public void SetPay (int. pay) {si this.pay = pay;55}56 public SET&L T Userbean2> GetUser () {user;58 return}59 public void SetUser (set<userbean2> user) {This.user = user;61}62 @Override63 public String Tostrin G () {Rolebean [id=] + ID + ", post=" + post + ", pay=" + Pay + "]"; 65}66}

2, in Hibernate.cfg.xml introduced UserBean2 and RoleBean2 these two classes of mappings:

1          <mapping class= "com.st.bean5.UserBean2"/>2          <mapping class= "com.st.bean5.RoleBean2"/>

3. Add a test method to the Beantest class:

 1 @Test 2 public void Bean5test1 () {3//Get a session 4 sessions session = Hibernatetools.opensession (); 5//Open a thing 6 Transaction tran = Session.begintransaction (); 7 UserBean2 user = new UserBean2 (); 8//RoleBean2 role = (RoleBean2) session.get (rolebean2.class,1l);         9 RoleBean2 role = new RoleBean2 (), User.setname ("Wang Wen Shi"), User.setsex ("male"); 13 Role.setpost ("Doctor"), Role.setpay (10000), Role.getuser (). Add (user), SE         Ssion.save (role); 19//Confirm the submission of things tran.commit ();}22 @Test23 public void Bean5test2 () {24 Gets a session Sessions session = Hibernatetools.opensession (); +/* list<userbean> List = Session.crea         Tecriteria (userbean.class). List (); UserBean user:list) System.out.println (user); */29 String hql = "Select New Map (U.name as name,u.sex as sex,r.post as post,R.pay as pay) from UserBean2 u join u.role r "; list<map<string,object>> List = Session.createquery (h QL). List (); map<string,object> data:list) System.out.println (data); 33}

Third, note:

1. After introducing the jar package required for annotations, delete the Java EE 5 Library, or the class in the two jar package will conflict

2, in the multi-table operation is best to set the cascade relationship, otherwise the table operation to read a class of data, and then add a new class of data to this class to successfully operate on three tables.

2.2, hibernate with annotations to achieve a one-to-many, many-to-many relationship