SpringBoot和JPA初探

news2024/11/17 21:35:29

SpringBoot和JPA初探

我们使用SpringBoot+JPA做一个简单的API接口演示，通过一个简单的例子让大家对Spring Data JPA有一个整体的认知。

0.准备条件

IntelliJ IDEA
jdk 1.8
mysql 8.0
maven 3.8.x

1.创建JPA项目

新建项目模块，IDEA默认的新增项目jdk版本较高，使用jdk1.8的建议使用阿里的项目初始化地址 https://start.aliyun.com 如下图所示：
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设置完成后录入

name [项目名称]
location [位置]
language 开发语言选择java
type 选择maven
group
artifact
package name 包名
jdk

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选择springboot版本和添加Spring Boot项目依赖。

Logbook
Spring Web
Spring Data JPA
Data Base

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点击next，生成简单的示例项目

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>
    <groupId>org.uz654</groupId>
    <artifactId>jpa</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>jpa</name>
    <description>jpa</description>
    <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>2.7.6</spring-boot.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>    
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <version>8.0.31</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </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>${spring-boot.version}</version>
                <configuration>
                    <mainClass>org.uz654.jpa.JpaApplication</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

2.项目

新增UserController

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;
import org.uz654.jpa.ch01.entity.User;
import org.uz654.jpa.ch01.repository.UserRepository;

@RestController
@RequestMapping(path="/api/v1")
public class UserController {

    @Autowired
    private UserRepository userRepository;

    @PostMapping(path = "user",consumes = {MediaType.APPLICATION_JSON_VALUE})
    public User addNewUser(@RequestBody User user) {
        return userRepository.save(user);
    }

    @GetMapping(path = "users")
    public Page<User> getAllUsers(Pageable pageable) {
        return userRepository.findAll(pageable);
    }

}

addNewUser的功能就是将用户提交的用户信息保存到数据库的操作。
getAllUsers 分页查询所有用户的信息返回到前端。

2.新增UserRepository接口

import org.springframework.data.jpa.repository.JpaRepository;
import org.uz654.jpa.ch01.entity.User;

public interface UserRepository extends JpaRepository<User, String> {
}

3.新增实体User

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;

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

@Data
@Entity
@Builder
@AllArgsConstructor
public class User {
    @Id
    private String id;

    private String name;

    private String email;

    public User() {
        this.id = UUID.randomUUID().toString();
    }
}

配置文件配置信息

server.port=8080
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=12345678
spring.jpa.generate-ddl=true

测试必然是必不可少的一部分，新增的JpaTest

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.test.annotation.Commit;
import org.springframework.util.Assert;
import org.uz654.jpa.ch01.entity.User;
import org.uz654.jpa.ch01.repository.UserRepository;

import javax.transaction.Transactional;
import java.util.List;
import java.util.UUID;

@DataJpaTest(properties = {
        "spring.datasource.url=jdbc:mysql://localhost:3306/test",
        "spring.datasource.username=root",
        "spring.datasource.password=12345678",
        "spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver",
        "hibernate.dialect=org.hibernate.dialect.MySQL8Dialect"
})
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Transactional
public class JpaTest {
    @Autowired
    private UserRepository userRepository;

    @Test
    @Commit
    public void testSaveUser(){
        User user = userRepository.save(User.builder().id(UUID.randomUUID().toString()).name("uz654").email("test@163.com").build());
        Assert.notNull(user);
        List<User> users = userRepository.findAll();
        System.out.println(users);
        Assert.notNull(users);
    }
}

整体的结构

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