springboot项目开发过程参考（Spring Data JPA + Spring Data REST）

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springboot项目开发参考，主要使用Spring Data JPA 和 Spring Data REST 实现

springboot项目开发过程参考（Spring Data JPA + Spring Data REST）

依赖环境

  • java

    jdk版本 1.8

  • maven

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    mvn -v
    3.6.3

开发工具

  • IDEA
  • postman 测试后端接口
  • vscode

新建项目

  • 项目结构

    DemoApplication： 项目启动类
    application.properties： 配置文件
    pom.xml： 运行环境，maven仓库

框架：Spring Data JPA + Spring Data REST

  • Spring Data JPA，使开发者使用极简的代码实现对数据库的访问和操作。它提供了包括增删改查等在内的基本功能，且易于扩展。
  • Spring Data REST，基于Spring Data的repository之上，可以把 repository 自动输出为REST资源，支持Spring Data JPA

1.导入maven依赖

pom.xml

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<?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>2.4.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</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-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--Spring Data REST-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-rest-webmvc</artifactId>
            <version>3.3.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <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>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.4.0</version>
                <configuration>
                    <includeSystemScope>true</includeSystemScope>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

2.properties文件

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#restful
spring.data.rest.base-path=/db
server.port=18888

#达梦
#spring.datasource.url=jdbc:dm://localhost:5236?schema=DEMOSTORE
#spring.datasource.username=SYSDBA
#spring.datasource.password=12345qwert
#spring.datasource.driver-class-name=dm.jdbc.driver.DmDriver
#spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.DmDialect
#spring.jpa.hibernate.ddl-auto=update
#spring.jpa.show-sql=true

#mysql
#com.mysql.cj.jdbc.Driver
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/demojava?characterEncoding=utf-8&serverTimezone=UTC&useSSL=false
spring.datasource.username=root
spring.datasource.password=123qwe

#spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.DmDialect
spring.jpa.hibernate.ddl-auto=update
#spring.jpa.hibernate.ddl-auto=create
spring.jpa.show-sql=true

3.entity

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package com.example.demo.entity;

import lombok.Data;
import javax.persistence.*;

@Entity  //jpa实体类标识
@Data    //LomBok插件，省略get set
//@Table(name = "SysUser") // 指定数据库的表名
public class SysUser {

    @Id  //主键
    private Integer userId;

    private String userName;

    private String userType;

    private String password;

}

4.repository

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package com.example.demo.repository;

import com.example.demo.entity.SysUser;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
// 相当于UserDao
// 将UserRepository继承JpaRepository就可以有对应的增删改查方法
public interface UserRepository extends JpaRepository<SysUser,Integer>{
}

不需要通过controller，即可使用postman查看接口

5.添加查询方法

  • 使用

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    import com.example.demo.entity.SysUser;
    import org.springframework.data.jpa.repository.JpaRepository;
    import org.springframework.data.jpa.repository.Query;
    import org.springframework.stereotype.Repository;

    import java.util.List;

    @Repository
    // 相当于UserDao
    // 将UserRepository继承JpaRepository就可以有对应的增删改查方法
    public interface UserRepository extends JpaRepository<SysUser,Integer>{

        public SysUser findByUserIdAndPassword(Integer userId, String password);

        @Query(value = "select * from sys_user u where u.user_id=?1 and u.password=?2", nativeQuery = true)
        public List<SysUser> findByOwnMethod(Integer userId, String password);

    }

  • jpa自动生成sql

    spring-data-jpa会根据方法的名字来自动生成sql语句，只需要按照方法定义的规则即可。

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    public SysUser findByUserIdAndPassword(Integer userId, String password);

    上面的方法findByUserIdAndPassword，以findBy开头，sql的where部分就是UserIdAndPassword，被spring-data-jpa翻译之后就编程了下面这种形态：

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    select * from user where userId = ? and password = ?

  • 自定义sql

    使用@Query注解，写原生sql

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    @Query(value = "select * from sys_user u where u.user_id=?1 and u.password=?2", nativeQuery = true)
    public List<SysUser> findByOwnMethod(Integer userId, String password);

6.service

主要有两个作用

  • 1 单独的服务

  • 2 包装repository供controller使用

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    public interface UserService {

        public SysUser findUserOrNot(Integer userId, String password);
    }
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    @Service
    public class UserServiceImpl implements UserService{
        private final UserRepository userRepository;

        @Autowired
        UserServiceImpl(UserRepository userRepository) {
            this.userRepository = userRepository;
        } 

        @Override
        public SysUser findUserOrNot(Integer userId, String password) {
            return userRepository.findByUserIdAndPassword(userId, password);
        }
    }

7.controller

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package com.example.demo.controller;

import com.example.demo.entity.SysUser;
import com.example.demo.repository.UserRepository;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@CrossOrigin
@RestController
@RequestMapping("/define")
public class UserController {

    @Autowired
    UserRepository userRepository;

    @Autowired
    UserService userService;

    @RequestMapping("/login")
    public ResponseEntity<Map> login(Integer userId, String password) {
        Map map = new HashMap<>();
        SysUser sysUser = userRepository.findByUserIdAndPassword(userId, password);
        map.put("code", "200");
        map.put("message", "success");
        map.put("user", sysUser);
        return new ResponseEntity<Map>(map, HttpStatus.OK);
    }

    @RequestMapping("/login2")
    public ResponseEntity<Map> login2(Integer userId, String password) {
        Map map = new HashMap<>();
        SysUser sysUser = userService.findUserOrNot(userId, password);
        map.put("code", "200");
        map.put("message", "success");
        map.put("user", sysUser);
        return new ResponseEntity<Map>(map, HttpStatus.OK);
    }

}

  • 1 直接访问repository 
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    http://localhost:18888/define/login?userId=1&password=123
  • 2 访问service 
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    http://localhost:18888/define/login2?userId=1&password=123

8.学习链接

Spring Data Jpa的使用：https://www.jianshu.com/p/c23c82a8fcfc