Accessing MySQL database with spring data JPA - configuration item

Dasheng play Java 2021-06-23 16:17:03
accessing mysql database spring data


jpa Operating the database

Be careful : The database is native database , The following is the table building statement and initialization data :
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` bigint(0) NOT NULL AUTO_INCREMENT COMMENT ' Primary key ID',
`dpt_id` bigint(0) NULL DEFAULT NULL COMMENT ' department id',
`name` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT ' full name ',
`age` int(0) NULL DEFAULT NULL COMMENT ' Age ',
`email` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT ' mailbox ',
`head_img` varchar(200) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT ' Head portrait ',
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 0 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = ' User class ' ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (1, 1, 'Jone', 18, 'test1@baomidou.com', 'e');
INSERT INTO `user` VALUES (2, 1, 'Jack', 20, 'test2@baomidou.com', 'd');
INSERT INTO `user` VALUES (3, 1, 'Tom', 28, 'test3@baomidou.com', 'c');
INSERT INTO `user` VALUES (4, 1, 'Sandy', 21, 'test4@baomidou.com', 'b');
INSERT INTO `user` VALUES (5, 1, 'Billie', 24, 'test5@baomidou.com', 'a');
SET FOREIGN_KEY_CHECKS = 1;

stay idea Configure data source in :idea-->view-->tool windows-->database

Create a project , Add the following dependencies

<!--springboot web rely on -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!--springboot Operate the database using jpa Dependence -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--mysql Database connection driver -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!--lombok An artifact , Later, we will introduce -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>

Under the created project application.yml Add the following database configuration

spring:
datasource:
url: jdbc:mysql://localhost:3306/demo?charset=UTF-8&serverTimezone=GMT%2B8
username: root
password: 123456
driver-class-name: com.mysql.cj.jdbc.Driver

Establish the project directory structure as follows

user Code :

@Entity// This is a corresponding database table entity class
@Data//lombok An annotation of artifact , Later, we will introduce
@Table ( name ="user" )// This class corresponds to which table in the database
public class User implements Serializable {
private static final long serialVersionUID = 829933141479418804L;
/**
* Primary key ID
*/
@Id// This field is the primary key of the database table
@Column(name = "id" )// Which field of the table does this attribute correspond to
@GeneratedValue(strategy= GenerationType.IDENTITY)// The primary key adopts the database auto increment method
private Long id;
/**
* department id
*/
@Column(name = "dpt_id" )
private Long dptId;
/**
* full name
*/
@Column(name = "name" )
private String name;
/**
* Age
*/
@Column(name = "age" )
private Long age;
/**
* mailbox
*/
@Column(name = "email" )
private String email;
/**
* Head portrait
*/
@Column(name = "head_img" )
private String headImg;
}

@GeneratedValue Annotated strategy Property provides four values :

  1. –AUTO: The primary key is controlled by the program , Is the default option , Do not set this item .
  2. –IDENTITY: The primary key is automatically generated by the database , That is to say, database is adopted ID The way of self growth ,Oracle Not in favor of this way .
  3. –SEQUENCE: Generating primary keys from a sequence of databases , adopt @SequenceGenerator The annotation specifies the sequence name ,mysql Not in favor of this way .
  4. –TABLE: Generate primary keys through specific database tables , Using this strategy can make the application easier to migrate .

userJpa Code :

@Repository// Indicates that this is a database operation Repository class
public interface UserJpa extends JpaRepository<User,Long> {
}

userController Code :

@RestController
@RequestMapping("user")
public class UserController {
@Resource
private UserJpa userJpa;
@GetMapping("findAll")// Find all the data
public List<User> findAll(){
return this.userJpa.findAll();
}
@GetMapping("get")// Find data by primary key
public User get(@RequestParam("id")Long id){
return this.userJpa.findById(id).get();
}
}

Start the project , And then use postman test : Query all :

The query id The data of

I didn't write a single one sql, That's how the data came out . Okay , This is the end of the section . The next section describes saving , Delete , to update , Customize sql

More original reading :https://javawu.com

版权声明
本文为[Dasheng play Java]所创,转载请带上原文链接,感谢
https://javamana.com/2021/06/20210623161643692a.html

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