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【简单实验】spring-boot-starter-data-jpa

2023-03-15 22:00:36 时间

1、项目目录

2、全部代码

2.1 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>jpademo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>jpademo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.27</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<!--        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.8</version>
        </dependency>-->

        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.2 application.properties

server.port=8080
server.servlet.context-path=/demo

#com.mysql.jdbc.Driver过时
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://192.168.203.101:3306/test
spring.datasource.username=test_admin
spring.datasource.password=123

2.3 生成的Application代码

package com.example.jpademo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class JpademoApplication {

    public static void main(String[] args) {
        SpringApplication.run(JpademoApplication.class, args);
    }

}

2.4 beans

package com.example.jpademo.beans;
import lombok.*;
import lombok.experimental.Accessors;
import org.springframework.format.annotation.DateTimeFormat;
import javax.persistence.*;
import java.io.Serializable;
import java.util.Date;
@Data
@NoArgsConstructor
@Accessors(chain = true)
@Entity
@Table(name = "users")
public class User implements Serializable{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date dt=new Date();

}

对应的数据库操作

mysql> create database test;
Query OK, 1 row affected (0.01 sec)

mysql> use test;
Database changed
mysql> create table users(
    -> id int auto_increment primary key,
    -> name varchar(45) ,
    -> dt datetime default CURRENT_TIMESTAMP
    -> );
Query OK, 0 rows affected (0.02 sec)

mysql> insert into users(name) values('test'),('abc'),('Hadron');
Query OK, 3 rows affected (0.01 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

mysql>

2.5 Repository

package com.example.jpademo.dao;
import com.example.jpademo.beans.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.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.stereotype.Repository;
import javax.transaction.Transactional;

@Repository
public interface UserRepository extends JpaRepository<User, Long>{

    //默认提供了Optional<User> findById(Long id);

    User findByName(String name);

    @Query("select u from User u where u.id <= ?1")
    Page<User> findMore(Long maxId, Pageable pageable);

    @Modifying
    @Transactional
    @Query("update User u set u.name = ?1 where u.id = ?2")
    int updateById(String  name, Long id);


}

2.6 Service

package com.example.jpademo.service;

import com.example.jpademo.beans.User;
import com.example.jpademo.dao.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;

@Service("userService")
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public User getUserByID(Long id){
        return userRepository.findById(id).get();
    }

    public User getByName(String name){
        return userRepository.findByName(name);
    }

    public Page<User> findPage(){
        Pageable pageable = PageRequest.of(0, 10);
        return userRepository.findAll(pageable);
    }

    public Page<User> find(Long maxId){
        Pageable pageable = PageRequest.of(0, 10);
        return userRepository.findMore(maxId,pageable);
    }

    public User save(User u){
        return userRepository.save(u);
    }

    public User update(Long id,String name){
        User user = userRepository.findById(id).get();
        user.setName(name+"_update");
        return userRepository.save(user);
    }

    public Boolean updateById(String  name, Long id){
        return userRepository.updateById(name,id)==1;
    }

}

2.7 Controller

package com.example.jpademo.web;

import com.example.jpademo.beans.User;
import com.example.jpademo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Optional;

@RestController
@RequestMapping("/")
public class ApiController {

    @Autowired
    private UserService userService;

    @GetMapping("/init")
    public String init(){
        User user = null;
        for(int i=0;i<10;i++){
            user = new User();
            user.setName("test"+i);
            userService.save(user);
        }
        return "初始化完成。";
    }

    @GetMapping("/userByName/{username}")
    public User getUserByName(@PathVariable("username") String username){
        return userService.getByName(username);
    }

    @GetMapping("/userById/{userid}")
    public User getUserById(@PathVariable("userid") Long userid){
        return userService.getUserByID(userid);
    }

    @GetMapping("/page")
    public Page<User> getPage(){
        return userService.findPage();
    }

    @GetMapping("/page/{maxID}")
    public Page<User> getPageByMaxID(@PathVariable("maxID") Long maxID){
        return userService.find(maxID);
    }

    @RequestMapping("/update/{id}/{name}")
    public User update(@PathVariable Long id, @PathVariable String name){
        return userService.update(id,name);
    }

    @RequestMapping("/update/{id}")
    public Boolean updateById(@PathVariable Long id){
        return userService.updateById("newName",id);
    }
}

3、测试

3.1 测试初始化接口

http://localhost:8080/demo/init

mysql> select * from users;
+----+--------+---------------------+
| id | name   | dt                  |
+----+--------+---------------------+
|  1 | test   | 2021-11-15 23:45:05 |
|  2 | abc    | 2021-11-15 23:45:05 |
|  3 | Hadron | 2021-11-15 23:45:05 |
|  4 | test0  | NULL                |
|  5 | test1  | NULL                |
|  6 | test2  | NULL                |
|  7 | test3  | NULL                |
|  8 | test4  | NULL                |
|  9 | test5  | NULL                |
| 10 | test6  | NULL                |
| 11 | test7  | NULL                |
| 12 | test8  | NULL                |
| 13 | test9  | NULL                |
+----+--------+---------------------+
13 rows in set (0.00 sec)

mysql>

发现dt字段没有值。解决办法：修改User类

	@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date dt=new Date();

然后重启程序，再次调用初始化接口http://localhost:8080/demo/init，查询数据库，问题解决。

mysql> select * from users;
+----+--------+---------------------+
| id | name   | dt                  |
+----+--------+---------------------+
|  1 | test   | 2021-11-15 23:45:05 |
|  2 | abc    | 2021-11-15 23:45:05 |
|  3 | Hadron | 2021-11-15 23:45:05 |
|  4 | test0  | NULL                |
|  5 | test1  | NULL                |
|  6 | test2  | NULL                |
|  7 | test3  | NULL                |
|  8 | test4  | NULL                |
|  9 | test5  | NULL                |
| 10 | test6  | NULL                |
| 11 | test7  | NULL                |
| 12 | test8  | NULL                |
| 13 | test9  | NULL                |
| 14 | test0  | 2021-11-16 19:07:56 |
| 15 | test1  | 2021-11-16 19:07:56 |
| 16 | test2  | 2021-11-16 19:07:56 |
| 17 | test3  | 2021-11-16 19:07:56 |
| 18 | test4  | 2021-11-16 19:07:56 |
| 19 | test5  | 2021-11-16 19:07:56 |
| 20 | test6  | 2021-11-16 19:07:56 |
| 21 | test7  | 2021-11-16 19:07:56 |
| 22 | test8  | 2021-11-16 19:07:56 |
| 23 | test9  | 2021-11-16 19:07:56 |
+----+--------+---------------------+
23 rows in set (0.00 sec)

mysql>

3.2 测试查询接口

http://localhost:8080/demo/userById/1

http://localhost:8080/demo/userByName/abc

3.3 测试分页查询接口

http://localhost:8080/demo/page

http://localhost:8080/demo/page/5

3.4 测试更新接口

mysql> select * from users where id=1;
+----+---------+---------------------+
| id | name    | dt                  |
+----+---------+---------------------+
|  1 | newName | 2021-11-15 23:45:05 |
+----+---------+---------------------+
1 row in set (0.00 sec)

mysql>

mysql> select * from users where id=1;
+----+----------------+---------------------+
| id | name           | dt                  |
+----+----------------+---------------------+
|  1 | newName_update | 2021-11-15 23:45:05 |
+----+----------------+---------------------+
1 row in set (0.00 sec)

mysql>

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