1、引入依賴(pom.xml)
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
2、數據庫連接配置(application.yml)
spring:
datasource:
url: jdbc:mysql://localhost/test
username: root
password: 123456
driver-class-name: com.mysql.jdbc.Driver
jpa:
hibernate:
dialect: org.hibernate.dialect.MySQL5InnoDBDialect
#根據實體類自動創建表,如果創建過就不再重新創建
ddl-auto: update
show-sql: true
3、實體類
package com.example.demospringbootjpa.bean;
import lombok.Data;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import java.io.Serializable;
import java.util.Date;
@Entity
@Data
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private Long id;
@Column(nullable = false, unique = true)
private String userName;
@Column
private Integer age;
@Column(nullable = false)
private String passWord;
@Column(nullable = false, unique = true)
private String email;
@Column(nullable = true, unique = true)
private String nickName;
@Column(nullable = false)
private Date regTime;
public User() {
}
public User(String userName, Integer age, String passWord, String email, String nickName, Date regTime) {
this.userName = userName;
this.age = age;
this.passWord = passWord;
this.email = email;
this.nickName = nickName;
this.regTime = regTime;
}
}
4、Dao層接口
package com.example.demospringbootjpa.repository;
import com.example.demospringbootjpa.bean.User;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import java.util.List;
public interface UserRepository extends JpaRepository<User, Long> {
//1、Query裏面的查詢不是Sql,是Hql,from 後面是Java實體名,查詢條件字段如userName也是Java實體對象的屬性!!!
@Query("select u from User u where u.userName = :userName")
User findByUserName(String userName);
//2、nativeQuery = true 使用原生的sql
@Query(value = "select * from user where email like concat('%',:email,'%') ",nativeQuery = true)
User findByEmail(String email);
}
5、測試查詢
@Test
public void contextLoads() {
Date date = new Date();
DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG);
userRepository.save(new User("dfas",12, "123456", "[email protected]", "asddsfd",date));
userRepository.save(new User("dfasdfasdf",14, "123456", "[email protected]", "dfasdf",date));
userRepository.save(new User("csdfsadfc3",15, "123456", "[email protected]", "fdfdfdf",date));
User user1 = userRepository.findByUserName("dfas");
User user2 = userRepository.findByEmail("[email protected]");
System.out.println(user1);
System.out.println(user2);
}
總結
今天才開始使用 jpa,遇到一個坑就是Dao層的接口自定義Sql總是報錯,原來@Query裏面的命令默認是Hql,如果要切換成Sql要使用 nativeQuery = true
。
本博客記錄了SpringBoot Data Jpa 的簡單使用,接下來應該着力學習一些 jpa 的高級用法~