Shulou(Shulou.com)06/01 Report--

Configuration mode

Pom dependence

Org.springframework.boot

Spring-boot-starter-aop

Application.xml configuration

# jpa configuration

Spring.jpa.properties.hibernate.hbm2ddl.auto=update

Spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect

Spring.jpa.show-sql= true

Spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

It should be noted that the last line is used to define the naming strategy. If it is not set, the default naming strategy will be used. For example, when creating a table, the hump named will be converted to full lowercase and separated with horizontal lines, such as: entity class name: userCommon. Mapping to the table name is user-common.

Mode of use

There are two ways to use jpa, one is to use annotations, the other is to use configuration files, both of which can be implemented, but annotations are recommended because it is more concise and is the mainstream trend.

Add the following comments to the entity classes that need to be mapped

@ Entity: indicates that this class is an entity class, and this annotation cannot be scanned by jpa until this annotation is added.

@ Table: table name can be customized

What we need to know is that the above two lines of annotations have completed the mapping of jpa. After being declared as an entity class, the attributes in this class will be mapped to the database by default, but the default often does not meet our requirements. For example, naming, length, primary key and index all need to be specified by ourselves, so here are some commonly used notes.

Extended comment

Add comments to the attribute

Primary key:

@ Id: commonly used to declare a primary key

@ GeneratedValue (strategy=GenerationType.IDENTITY): set the primary key to self-increment

General attribute: http://www.87554006.com/ of Wuxi Gynecological examination Hospital

@ column: you can customize column names or define other data types

For example, @ column (name= "content", columnDefinition = "longtext")

@ Transient: no database mapping, similar to exclusion

The page gets the value of the formatted type directly, mainly for the date type

@ Temporal (TemporalType.DATE): such as 1994-05-06

@ Temporal (TemporalType.TIME): 20:46:13

Temporal (TemporalType.TIMESTAMP): 1994-05-06 20:46:13

Unique index

@ Table (name = "table name", uniqueConstraints = {

@ UniqueConstraint (name = "Index name", columnNames = {"Field 1", "Field 2"})

})

Table plus index index

@ Table (name = "table name", indexes = {

@ Index (name = "index name", columnList = "field name")

})

Database initialization

The initialization of the database is often used. The database we create generally needs some initialized data. The configuration is as follows.

Add application.properties profile properties

Spring.datasource.data=classpath:database/data.sql

Spring.datasource.sql-script-encoding=utf-8

Spring.datasource.initialization-mode=ALWAYS

Create the data.sql file, which will be executed when the project starts. If the project data has been initialized, you can change the property ALWAYS of the last line to NEVER.

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