Simple integration with Spring-boot and SPRING-DATA-JPA

How to easily use JPA in boot

<!--first introduce JPA dependency--
<dependency>  <groupId>org.springframework.boot</groupId>  <artifactId> Spring-boot-starter-data-jpa</artifactid></dependency>

Take the user role as an example, where the user table, the role table, and an intermediate table, the User Role table, first create the corresponding entity class

/** * User class */  @Data @entitypublic class Account extends Defaultvalidate implements Login {    @Id    @GeneratedValue    private Integer ID;     /**     * Login name */    @NotNull (message = "Login cannot be empty")    @Size (min = 2, max = @Column)    (name= "login_name")    private String loginName;     /**     * Account name */    @NotNull (message = "account name cannot be empty")    @Size (min = 2, max =)    @Column (name= "Account_ Name ")    private String accountname;     /**     * Login Password     *    /@Column (name= "login_pwd")    private String loginpwd;         /**     * Account Identification Code     *    /@Column (name= "Account_code")    private String accountcode;         /**     * Intermediate tables   do not require entity classes to  automatically generate     *    /@ManyToMany (cascade=cascadetype.refresh,fetch=fetchtype.lazy )    @JoinTable (name = "Account_role",    joincolumns = {@JoinColumn (name = "account_id")},     Inversejoincolumns = {@JoinColumn (name = "role_id")})    private set<role> roles = new hashset<role> ();}

　　

　　

/* Role class * @date March 22, 2018 10:17:11 */@Data @entitypublic class role extends Defaultvalidate {    @Id    @GeneratedVal UE    private Integer ID;     /**     * Role ID */    @NotNull (message = "Role identity cannot be empty")    @Size (min = 2, max =    @Column) (name= "Role_code")    private String Rolecode;     /**     * * Role name */    @NotNull (message = "Role name cannot be empty")    @Size (min = 2, max =    @Column) (name= "Role_name ")    private String roleName;}

The corresponding entity class is created, and the mapping relationship used above is a one-way, many-to-many, followed by the creation of the corresponding repository

@Repositorypublic interface Accountreposity extends Jparepository<account, integer> {     }

The corresponding method can be called when using it. Then to introduce the corresponding dynamic query, dynamic query needs repository inherit Jpaspecificationexecutor class,

Public page<flow> mysubmission (mysubmitpagedto selectdto) {logger.info ("Query my submission start ....") ") ; Pagerequest pageable =new pagerequest (Selectdto.getpagenum (), selectdto.getpagesize ());//anonymous inner class specification< flow> specification = new specification<flow> () {/** * predicate: Represents a query condition * Root: Query entity class * Query: You can get the root object from which to tell Query that entity class, add the query criteria (where the ordering can be set by query) * CB: Used to create criteriabuilder related objects of the factory, from which you can get to predicate object */@Overridepublic predicate Topredicate (root<flow> Root, criteriaquery<?> query, Criteriabuilder CB) {list<predicate> Predicatelist = new arraylist<predicate> ();p Redicatelist.add (Cb.equal (Root.<string>get ("FlowStarter") , Selectdto.getusercode ())); Predicate[] P =new predicate[predicatelist.size ()];return Cb.and (Predicatelist.toarray (P));}}; page<flow> page = Flowrepository.findall (specification, pageable); Logger.info ("Query my submission end ....") "); return page;}

　　

If there is a very complex dynamic query, it is recommended to combine SPRING-JDBC to operate, write dynamic native SQL is easier to develop.

Life cycle of JPA objects:

New: Instantaneous object, no ID yet, and object associated with persistence context.

Managed: Persisted managed object, with ID value, has already established an associated object with persistence context.

Datached: A free-form offline object with an ID value, but no associated object with persistence context.

Removed: deleted object with ID value, still associated with persistence context, but ready to remove from database

When the JPA query object is in a persistent state, the database is changed dynamically when the set method of the object property is called. can be done by

@PersistenceContext
Private Entitymanager Entitymanger;

Call the manager's clear method to release the object.

If an enumeration class property is involved, you can override its Set,get method, such as:

Public Warehousestatusenum GetState () {return warehousestatusenum.getwarehousestatusenum (this.state);} public void SetState (Warehousestatusenum state) {this.state = State.value ();}

　　

Simple integration with Spring-boot and SPRING-DATA-JPA