01-hibernate annotations: Class-level annotations, @Entity, @Table, @Embeddable

@Entity

@Entity: Mapping entity classes

@Entity (name= "TableName")

Name: optional, corresponds to a table in the database and can be omitted if the table name is the same as the entity class name.

Note: You must specify the primary key attribute of the entity class when using @entity.

First step: Create the Entity class:

Add @Entity Annotations to the class name, respectively. Add a @Id annotation to the Get method that is the property of the primary key in the class.

 Packagecom.entity;Importjava.util.Date;Importjavax.persistence.Entity;/*JPA PRIMARY Key*/Importjavax.persistence.Id;/*Student entity class*/@Entity (name= "Students") Public classStudents {Private intSID; PrivateString sname;//name    PrivateString gender;//Sex    PrivateDate birthday; PrivateString Major;//Professional    PrivateString address;//Address         PublicStudents () {} PublicStudents (intsid, String sname, String gender, Date birthday, String major, string address) {        //super ();         This. Sid =SID;  This. sname =sname;  This. Gender =gender;  This. Birthday =birthday;  This. Major =Major;  This. Address =address; } @Id  Public intGetSID () {returnSID; }     Public voidSetsid (intSID) {         This. Sid =SID; }     PublicString Getsname () {returnsname; }     Public voidsetsname (String sname) { This. sname =sname; }     PublicString Getgender () {returngender; }     Public voidSetgender (String gender) { This. Gender =gender; }     PublicDate Getbirthday () {returnbirthday; }     Public voidsetbirthday (Date birthday) { This. Birthday =birthday; }     PublicString getmajor () {returnMajor; }     Public voidSetmajor (String major) { This. Major =Major; }     PublicString getaddress () {returnaddress; }     Public voidsetaddress (String address) { This. Address =address; }    }

The second step: Configure this class in the configuration.

The third step: Write the Test class:

 Packagecom.entity;ImportJava.util.EnumSet;ImportOrg.hibernate.boot.Metadata;Importorg.hibernate.boot.MetadataSources;ImportOrg.hibernate.boot.registry.StandardServiceRegistryBuilder;ImportOrg.hibernate.service.ServiceRegistry;ImportOrg.hibernate.tool.hbm2ddl.SchemaExport;ImportOrg.hibernate.tool.schema.TargetType;Importorg.junit.Test; Public classteststudents { @Test  Public voidTestschemaexport () {//Create a Service registration objectServiceregistry Serviceregistry =Newstandardserviceregistrybuilder (). Configure (). build (); //Create a metadata objectMetadata Metadata =Newmetadatasources (serviceregistry). Buildmetadata (); //Create a Schemaexport objectSchemaexport export =NewSchemaexport ();    Export.create (Enumset.of (targettype.database), metadata); }}

After debugging, the tables are normally generated in the database.

@Table

@Table (name= "", catalog= "", Schema= "")

@Entity used in conjunction, can only be labeled at the class definition of the entity class, representing the information of the database table corresponding to the entity.

Name: optional, map table name, default table name and entity name are the same, only need to specify table name in case of inconsistency.

Catalog: Optional, the catalog name, the default is: Catalog ("").

Schema (Schema): Optional, representing the schema name, default: Schema ("").

Table Annotation instance: changes to the previous entity are as follows:

Name: Before the table name, Schema: default to the database name used

@Embeddable

Indicates that a non-entity class can be embedded in another entity class as an attribute.

is equivalent to the component property that replaces the previous single-pen operation .

The first step is to build a non-entity class and add @embeddable annotations before it.

 Packagecom.entity;Importjavax.persistence.Embeddable; @Embeddable /*represents an embedded class that acts as a property in another entity class*/ Public classAddress {PrivateString postcode;//Postal Code    PrivateString address;//Address    PrivateString Phone;  PublicAddress () {} PublicString Getpostcode () {returnpostcode; }     Public voidSetpostcode (String postcode) { This. Postcode =postcode; }     PublicString getaddress () {returnaddress; }     Public voidsetaddress (String address) { This. Address =address; }     PublicString Getphone () {returnphone; }     Public voidSetphone (String phone) { This. Phone =phone; }    }

Step Two: Add the object of this class to the entity class and add the Set,get method.

Step Three: Test:

Discovery builds successfully as required.

01-hibernate annotations: Class-level annotations, @Entity, @Table, @Embeddable