springboot integration jpa project entry level demo

preface
1, Create an empty boot project
2, Prepare the database, mainly MySQL
3, Import dependency
4, Generate JPA entities
5, JPA basic notes
6, JPQL and EntityManager
7, Configuration file
8, demo package

preface

Simple basic entry level, no fragrance if you have a foundation!

1, Create an empty boot project

Just create it like a fool

2, Prepare the database, mainly MySQL

Create the test table and dog table for later use

3, Import dependency

The following dependencies, which will be used later, are posted directly
org.springframework.boot spring-boot-starter-web org.springframework.boot spring-boot-starter-data-jpa mysql mysql-connector-java runtime org.projectlombok lombok 1.16.14 com.alibaba fastjson 1.2.76

4, Generate JPA entities

JPA automatically generates JPA entity class (idea).

5, JPA basic notes

@entity
@Table(name="table_name")
This annotation is required when the current entity is different from its mapped database table name. If it is consistent, it is OK not to add it
@Id primary key
@GeneratedValue
Generation strategy of primary key, for example: @ GeneratedValue(strategy = GenerationType.AUTO)
@Basic
Represents the mapping of a simple attribute to the fields of the database table. For the getXXX() method without any annotation, the default is @ basic, which will map XXX to a column of the database
That is, @ Basic is added by default if no annotation is added to the entity's get method (this annotation can be added or not)
@Column(name = "dog_name") maps the database field name
@Transient indicates that the attribute is not a mapping to the field of the database table. The ORM framework will ignore this attribute. If an attribute is not a mapping to the field of the database table, it must be marked as @ transient. Otherwise, the ORM framework defaults to its annotation as @ basic
@Temporal(TemporalType.DATE)
This annotation can be used to adjust the accuracy of the database storage date during attribute mapping (by setting: TemporalType.DATE, TemporalType.TIMESTAMP)

6, JPQL and EntityManager

The simple entry code is as follows:

Entity: automatically generated by JPA

package com.liu.susu.pojo;

import javax.persistence.*;
import java.util.Objects;

@NamedQuery(name = "testNamedQuery",query = "select d from com.liu.susu.pojo.Dog d")
@Entity
public class Dog {
private int dogNum;
private String dogName;
private String dogKind;
private Integer dogAge;
private String decision;

public Dog(){

}

public Dog(int dogNum, String dogName) {
    this.dogNum = dogNum;
    this.dogName = dogName;
}

@Id
@Column(name = "dog_num")
public int getDogNum() {
    return dogNum;
}

public void setDogNum(int dogNum) {
    this.dogNum = dogNum;
}

@Basic
@Column(name = "dog_name")
public String getDogName() {
    return dogName;
}

public void setDogName(String dogName) {
    this.dogName = dogName;
}

@Basic
@Column(name = "dog_kind")
public String getDogKind() {
    return dogKind;
}

public void setDogKind(String dogKind) {
    this.dogKind = dogKind;
}

@Basic
@Column(name = "dog_age")
public Integer getDogAge() {
    return dogAge;
}

public void setDogAge(Integer dogAge) {
    this.dogAge = dogAge;
}

@Basic
@Column(name = "decision")
public String getDecision() {
    return decision;
}

public void setDecision(String decision) {
    this.decision = decision;
}

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Dog dog = (Dog) o;
    return dogNum == dog.dogNum && Objects.equals(dogName, dog.dogName) && Objects.equals(dogKind, dog.dogKind) && Objects.equals(dogAge, dog.dogAge) && Objects.equals(decision, dog.decision);
}

@Override
public int hashCode() {
    return Objects.hash(dogNum, dogName, dogKind, dogAge, decision);
}

}

Two dao

package com.liu.susu.dao;

import com.liu.susu.pojo.Dog;
import org.springframework.data.jpa.repository.JpaRepository;

public interface DogDao extends JpaRepository<Dog,Integer> {

}

package com.liu.susu.dao;

import com.liu.susu.pojo.Dog;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;

import java.util.List;

/**
- jpql query
  /
  public interface DogDao2 extends JpaRepository<Dog,Integer> {
  /*
  - Check all without restrictions
  - @return
    */
    @Query(value = "from com.liu.susu.pojo.Dog")
    List getDogList();
  /**
  - Give an alias d, similar to query select*
  - @return
    */
    @Query(value = "select d from com.liu.susu.pojo.Dog d")
    List getDogList2();
  /**
  - In this way, the query result set of specific fields is not encapsulated in the entity object,
  - ```
      It's encapsulated in Object[]in
```
- @return
  */
  @Query(value = "select dogNum,dogName from com.liu.susu.pojo.Dog d")
  List<Object[]> getDogObjectList();
/**
- new, so the query result is directly encapsulated in the corresponding entity, but the corresponding constructor is required
- ```
     Therefore, if there are many fields to check, it will be more troublesome·
```
  - @return
    */
    @Query(value = "select new com.liu.susu.pojo.Dog(dogNum,dogName) from com.liu.susu.pojo.Dog d")
    List getDogList3();
  /**
  - Query by criteria
  - @return
    */
    @Query(value = "select d from com.liu.susu.pojo.Dog d where d.dogAge=?1")
    List getDogList0(int dogAge);
}

4 controller s

package com.liu.susu.controller;

import com.alibaba.fastjson.JSONObject;
import com.liu.susu.dao.DogDao;
import com.liu.susu.pojo.Dog;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.List;

@Controller
@RequestMapping("/dog/dao1")
public class DogDaoController {

@Autowired
private DogDao dogDao;

/**
 * Query all
 * @return
 */
@ResponseBody
@RequestMapping("/all")
public String testFindAll(){
    List<Dog> dogList = dogDao.findAll();
    return JSONObject.toJSONString(dogList);
}
/**
 * Query all and sort by dogAge field
 * @return
 */
@ResponseBody
@RequestMapping("/all2")
public List<Dog> testFindAll2(){

// List dogList = dogDao.findAll(Sort.by(“dogAge”));// Default ascending order
List dogList = dogDao.findAll(Sort.by("dogAge").descending());
return dogList;
}
/**
*Query all and sort by dogAge field
* @return
*/
@ResponseBody
@RequestMapping("/save")
public List testSave(){
Dog dog = new Dog();
dog.setDogNum(1005);// Add primary key
dog.setDogName("Su Ni");
dog.setDogAge(1);
dogDao.save(dog);// Save new
List dogList = dogDao.findAll();
return dogList;
}

}

package com.liu.susu.controller;

import com.liu.susu.dao.DogDao2;
import com.liu.susu.pojo.Dog;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.List;

@Controller
@RequestMapping("/dog/dao2")
public class DogDao2Controller {
@Autowired
private DogDao2 dogDao2;

@ResponseBody
@RequestMapping("/list")
private List<Dog> getDogList(){
    List<Dog> dogList = dogDao2.getDogList();
    return dogList;
}
@ResponseBody
@RequestMapping("/list2")
private List<Dog> getDogList2(){
    List<Dog> dogList = dogDao2.getDogList2();
    return dogList;
}
@ResponseBody
@RequestMapping("/objList")
private List<Object[]> getDogObjectList(){
    List<Object[]> dogObjectList = dogDao2.getDogObjectList();
    return dogObjectList;
}
@ResponseBody
@RequestMapping("/list3")
private List<Dog> getDogList3(){
    List<Dog> dogList = dogDao2.getDogList3();
    return dogList;
}
/**
 * Query by criteria
 * @param dogAge
 * @return
 */
@ResponseBody
@RequestMapping("/listByDogAge")
private List<Dog> getDogListByParam(@RequestParam int dogAge){
    List<Dog> dogList = dogDao2.getDogList0(dogAge);
    return dogList;
}

}

package com.liu.susu.controller;

import com.liu.susu.pojo.Dog;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import javax.transaction.Transactional;
import java.util.List;

@Controller
@RequestMapping("/dog/entityManager1")
public class EntityManagerController {

@PersistenceContext
private EntityManager entityManager;

@ResponseBody
@RequestMapping("/list1")
public List<Dog> getDogList(){
    String sql = "select * from dog";
    List<Dog> dogList = entityManager.createNativeQuery(sql)
            .getResultList();//The result is only attribute value, not attribute name
    return dogList;
}
@ResponseBody
@RequestMapping("/list2")
public List<Dog> getDogList2(){
    String sql = "select * from dog";
    List<Dog> dogList = entityManager.createNativeQuery(sql,Dog.class)
            .getResultList();//Result = = > has attribute name
    return dogList;
}
/**
 * sql injection
 *    Query by parameters
 * @param dogNum
 * @return
 */
@ResponseBody
@RequestMapping("/dog1")
public Dog getDogByNum(@RequestParam Integer dogNum){
    String sql = "select * from dog d where d.dog_num=?1";
    Query query = entityManager.createNativeQuery(sql,Dog.class);
    query.setParameter(1,dogNum);
    Dog dog = (Dog) query.getSingleResult();
    return dog;
}
@ResponseBody
@RequestMapping("/save")
@Transactional()//Remember to add transaction annotation
public String testPersist(){
    Dog dog = new Dog();
    dog.setDogNum(1006);
    dog.setDogName("test");
    dog.setDogAge(0);
    entityManager.persist(dog);//Direct insert
    return "ok";
}
@ResponseBody
@RequestMapping("/merge")
@Transactional()//Remember to add transaction annotation
public String testMerge(){
    Dog dog = new Dog();
    dog.setDogNum(1006);
    dog.setDogName("Test 2");
    dog.setDogAge(0);
    entityManager.merge(dog);//Internal principle: query according to the primary key first and then update
    return "ok";
}

}

package com.liu.susu.controller;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import java.util.List;

@Controller
@RequestMapping("/dog/jpqlAndEntityManager")
public class JpqlAndEntityManagerController {

@PersistenceContext
private EntityManager entityManager;

@ResponseBody
@RequestMapping("/list1")
public List<Dog> getDogList(){
    List<Dog> dogList = entityManager.createNamedQuery("testNamedQuery")
            .getResultList();
    return dogList;
}

}

7, Configuration file

to configure

server.port=8993

apply name

spring.application.name=springboot-jpa

Database driver:

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

Database connection address

spring.datasource.url=jdbc:mysql://localhost:3306/liu?serverTimezone=UTC

Database user name & password:

spring.datasource.username=root
spring.datasource.password=root

#spring.jpa.generate-ddl=true
#spring.jpa.hibernate.ddl-auto=validate
spring.jpa.show-sql=true

Specifies the type of database

spring.jpa.database-platform=org.hibernate.dialect.MySQL57InnoDBDialect

pom

<?xml version="1.0" encoding="UTF-8"?>

4.0.0
com.liu.susu
springboot-jpa
0.0.1-SNAPSHOT
springboot-jpa
Demo project for Spring Boot

<properties>
    <java.version>1.8</java.version>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <spring-boot.version>2.3.2.RELEASE</spring-boot.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!--book demo Core dependency begin-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.16.14</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.76</version>
    </dependency>
    <!--book demo Core dependency end-->

</dependencies>


<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>${spring-boot.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <version>2.3.7.RELEASE</version>
            <configuration>
                <mainClass>com.liu.susu.SpringbootJpaApplication</mainClass>
            </configuration>
            <executions>
                <execution>
                    <id>repackage</id>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

8, demo package

spring boot integrates JPA -- demo

Keywords: Java Front-end Spring Spring Boot html

Added by phpmoron on Sat, 05 Mar 2022 17:46:11 +0200

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springboot integration jpa project entry level demo