SpringBoot整合Spring Data JPA實現增刪改查

根據springboot模板創建項目

訪問Spring Initializr：https://start.spring.io/，填好後點擊Generate - Ctrl ，下載後解壓到工作目錄，IDEA打開項目

打開之後配置Maven：File---Settings，搜索maven，選擇所在maven目錄

選擇Jdk：打開Project Structure，選擇jdk，我的是1.8

pom.xml文件導入Swagger和JPA的依賴，選擇web

<?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>2.2.1.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example.springdatajpa</groupId>
	<artifactId>springdatajpa</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springdatajpa</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-web</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>

        <!-- swagger -->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>
        <!-- jpa -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!-- mysql -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
	</dependencies>

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

</project>

swagger 配置：springdatajpa下新建config文件夾，在裏面創建個SwaggerConfig類

package com.example.springdatajpa.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2
public class SwaggerConfig {

    @Bean
    public Docket createRestApi(){
        return new Docket(DocumentationType.SWAGGER_2).apiInfo(apiInfo())
                .select()
                .apis(RequestHandlerSelectors.any())
                .paths(PathSelectors.any()).build();
    }

    private ApiInfo apiInfo(){
        return new ApiInfoBuilder()
                .title("SpringBoot API Doc")
                .description("This is a restful api document of Spring Data Jpa.")
                .version("1.0")
                .build();
    }

}

在config裏再新建個PageQuery類用於封裝分頁請求

package com.example.springdatajpa.config;
/**
 * 分頁請求
 */
public class PageQuery {
    /**
     * 當前頁碼
     */
    private int pageNum;
    /**
     * 每頁數量
     */
    private int pageSize;

    public int getPageNum() {
        return pageNum;
    }
    public void setPageNum(int pageNum) {
        this.pageNum = pageNum;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
}

配置數據源：把application.properties文件改名爲application.yml

server:
  port: 8080
spring:
  datasource:
    driverClassName: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springdatajpa?useUnicode=true&characterEncoding=utf-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
    username: root
    password: root
  jpa:
    show-sql: true # 默認false，在日誌裏顯示執行的sql語句
    database: mysql
    hibernate.ddl-auto: update #指定爲update，每次啓動項目檢測表結構有變化的時候會新增字段，表不存在時會新建，如果指定create，則每次啓動項目都會清空數據並刪除表，再新建
    properties.hibernate.dialect: org.hibernate.diale ct.MySQL5Dialect
    database-platform: org.hibernate.dialect.MySQL5Dialect
    hibernate:
      naming:
        implicit-strategy: org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyJpaImpl #指定jpa的自動錶生成策略，駝峯自動映射爲下劃線格式
        #physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

創建目錄結構：springdatajpa目錄下新建model，controller，service，serviceImpl，dao目錄結構，分別在底下新建對應的類和接口

model下SysUser

package com.example.springdatajpa.model;

import javax.persistence.*;

@Entity
@Table(name = "sys_user", indexes = {@Index(name = "id", columnList = "id", unique = true), @Index(name = "name ", columnList = "name", unique = true)})
public class SysUser {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    // @Column： 對應數據庫列名,可選, nullable 是否可以爲空, 默認true
    @Column(name = "name", nullable = false)
    private String name;

    private String password;

    private String email;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

controller下SysUserController

package com.example.springdatajpa.controller;

import com.example.springdatajpa.config.PageQuery;
import com.example.springdatajpa.model.SysUser;
import com.example.springdatajpa.service.SysUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("user")
public class SysUserController {

    @Autowired
    private SysUserService sysUserService;

    @PostMapping(value = "/save")
    public Object save(@RequestBody SysUser sysUser) {
        sysUserService.save(sysUser);
        return 200;
    }

    @PostMapping(value = "/delete")
    public Object delete(@RequestBody SysUser sysUser) {
        sysUserService.delete(sysUser);
        return 200;
    }

    @GetMapping(value = "/findAll")
    public Object findAll() {
        return sysUserService.findAll();
    }

    @PostMapping(value = "/findPage")
    public Object findPage(@RequestBody PageQuery pageQuery) {
        return sysUserService.findPage(pageQuery);
    }

}

service下SysUserService

package com.example.springdatajpa.service;

import com.example.springdatajpa.config.PageQuery;
import com.example.springdatajpa.model.SysUser;

import java.util.List;

public interface SysUserService {

    public void save(SysUser sysUser);

    public void delete(SysUser sysUser);

    public List<SysUser> findAll();

    public Object findPage(PageQuery pageQuery);

}

serviceImpl下SysUserServiceImpl

package com.example.springdatajpa.service.serviceImpl;

import com.example.springdatajpa.config.PageQuery;
import com.example.springdatajpa.dao.SysUserDao;
import com.example.springdatajpa.model.SysUser;
import com.example.springdatajpa.service.SysUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.PageRequest;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class SysUserServiceImpl implements SysUserService {

    @Autowired
    private SysUserDao sysUserDao;

    @Override
    public void save(SysUser sysUser){
        sysUserDao.save(sysUser);
    }

    @Override
    public void delete(SysUser sysUser){
        sysUserDao.delete(sysUser);
    }

    @Override
    public List<SysUser> findAll(){
        return sysUserDao.findAll();
    }

    @Override
    public Object findPage(PageQuery pageQuery){
        return sysUserDao.findAll(PageRequest.of(pageQuery.getPageNum(),pageQuery.getPageSize()));
    }

}

dao下SysUserDao，繼承了JpaRepository，裏面不用寫任何方法

package com.example.springdatajpa.dao;

import com.example.springdatajpa.model.SysUser;
import org.springframework.data.jpa.repository.JpaRepository;

import java.io.Serializable;

public interface SysUserDao extends JpaRepository<SysUser, Long>, Serializable {
}

啓動項目，訪問http://localhost:8080/swagger-ui.html，如下界面

點擊sys-user-controller下的save，展開後點擊Try it out

輸入參數信息，點擊Execute

成功

其他的方法就不一一試了.....來了解一下Spring Data JPA

Spring Data JPA爲Java Persistence API（JPA）提供了存儲庫支持。它簡化了需要訪問JPA數據源的應用程序的開發。

Spring Data存儲庫抽象中的中央接口是Repository。它需要域類以及域類的ID類型作爲類型參數來進行管理。該CrudRepository規定對於正在管理的實體類複雜的CRUD功能。

CrudRepository界面

public interface CrudRepository<T, ID> extends Repository<T, ID> {

  <S extends T> S save(S entity);      

  Optional<T> findById(ID primaryKey); 

  Iterable<T> findAll();               

  long count();                        

  void delete(T entity);               

  boolean existsById(ID primaryKey);   

  // … more functionality omitted.
}

save	保存給定的實體。
findById	返回由給定ID標識的實體。
findAll	返回所有實體。
count	返回實體數。
delete	刪除給定的實體。
existsById	指示是否存在具有給定ID的實體。

還提供了特定於持久性技術的抽象，例如JpaRepository或MongoRepository。這些接口CrudRepository除了擴展了與持久性技術無關的通用接口（例如）之外，還擴展並公開了基礎持久性技術的功能CrudRepository。

PagingAndSortingRepository界面，實現了排序和分頁的方法

public interface PagingAndSortingRepository<T, ID> extends CrudRepository<T, ID> {

  Iterable<T> findAll(Sort sort);

  Page<T> findAll(Pageable pageable);
}

JpaRepository又在繼承PagingAndSortingRepository的基礎上，同時繼承了QueryByExampleExecutor接口

JpaRepository界面

package org.springframework.data.jpa.repository;

import java.util.List;
import javax.persistence.EntityManager;
import org.springframework.data.domain.Example;
import org.springframework.data.domain.Sort;
import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.QueryByExampleExecutor;

/**
 * JPA specific extension of {@link org.springframework.data.repository.Repository}.
 *
 * @author Oliver Gierke
 * @author Christoph Strobl
 * @author Mark Paluch
 */
@NoRepositoryBean
public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.CrudRepository#findAll()
     */
    List<T> findAll();

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.PagingAndSortingRepository#findAll(org.springframework.data.domain.Sort)
     */
    List<T> findAll(Sort sort);

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.CrudRepository#findAll(java.lang.Iterable)
     */
    List<T> findAllById(Iterable<ID> ids);

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.CrudRepository#save(java.lang.Iterable)
     */
    <S extends T> List<S> saveAll(Iterable<S> entities);

    /**
     * Flushes all pending changes to the database.
     */
    void flush();

    /**
     * Saves an entity and flushes changes instantly.
     *
     * @param entity
     * @return the saved entity
     */
    <S extends T> S saveAndFlush(S entity);

    /**
     * Deletes the given entities in a batch which means it will create a single {@link Query}. Assume that we will clear
     * the {@link javax.persistence.EntityManager} after the call.
     *
     * @param entities
     */
    void deleteInBatch(Iterable<T> entities);

    /**
     * Deletes all entities in a batch call.
     */
    void deleteAllInBatch();

    /**
     * Returns a reference to the entity with the given identifier. Depending on how the JPA persistence provider is
     * implemented this is very likely to always return an instance and throw an
     * {@link javax.persistence.EntityNotFoundException} on first access. Some of them will reject invalid identifiers
     * immediately.
     *
     * @param id must not be {@literal null}.
     * @return a reference to the entity with the given identifier.
     * @see EntityManager#getReference(Class, Object) for details on when an exception is thrown.
     */
    T getOne(ID id);

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example)
     */
    @Override
    <S extends T> List<S> findAll(Example<S> example);

    /*
     * (non-Javadoc)
     * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example, org.springframework.data.domain.Sort)
     */
    @Override
    <S extends T> List<S> findAll(Example<S> example, Sort sort);
}

SysUserDao繼承了JpaRepository，因而可以使用JpaRepository之上的所有接口，由此更加方便我們進行開發

spring data jpa方法命名規則，直接在接口中定義查詢方法，如果是符合規範的，可以不用寫實現

關鍵字	方法命名	sql where字句
And	findByNameAndPwd	where name= ? and pwd =?
Or	findByNameOrSex	where name= ? or sex=?
Is,Equals	findById,findByIdEquals	where id= ?
Between	findByIdBetween	where id between ? and ?
LessThan	findByIdLessThan	where id < ?
LessThanEquals	findByIdLessThanEquals	where id <= ?
GreaterThan	findByIdGreaterThan	where id > ?
GreaterThanEquals	findByIdGreaterThanEquals	where id > = ?
After	findByIdAfter	where id > ?
Before	findByIdBefore	where id < ?
IsNull	findByNameIsNull	where name is null
isNotNull,NotNull	findByNameNotNull	where name is not null
Like	findByNameLike	where name like ?
NotLike	findByNameNotLike	where name not like ?
StartingWith	findByNameStartingWith	where name like '?%'
EndingWith	findByNameEndingWith	where name like '%?'
Containing	findByNameContaining	where name like '%?%'
OrderBy	findByIdOrderByXDesc	where id=? order by x desc
Not	findByNameNot	where name <> ?
In	findByIdIn(Collection<?> c)	where id in (?)
NotIn	findByNameNot	where name <> ?
True	findByAaaTue	where aaa = true
False	findByAaaFalse	where aaa = false
IgnoreCase	findByNameIgnoreCase	where UPPER(name)=UPPER(?)
top	findTop100	top 10/where ROWNUM <=10