SpringData核心数据访问接口--PagingAndSortingRepository

PagingAndSortingRepository继承自CrudRepository接口，所以除了拥有CrudReposirory的功能外，他还增加了排序和分页查询的功能。

创建一个Maven项目，在src/main下新建一个名为resources的文件夹。

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
4.0.0

  org.springframework.boot
  spring-boot-starter-parent
  2.0.0.RELEASE



  UTF-8
  UTF-8
  1.8

  org.springframework.boot
  spring-boot-starter-web

  org.springframework.boot
  spring-boot-starter-thymeleaf


  mysql
  mysql-connector-java




  org.springframework.boot
  spring-boot-starter-data-jpa


      junit
      junit
      test

在src/main/resources下新建一个全局配置文件，命名为application.properties

########################################################
### JPA持久化配置
########################################################
# 指定数据库类型
spring.jpa.database=MySQL
# 指定是否需要在日志中显示sql语句
spring.jpa.show-sql=true
# 指定自动创建|更新|验证数据库表结构等配置
# 表示如果数据库中存在持久化类对应的表就不创建，不存在就创建对应的表
spring.jpa.hibernate.ddl-auto=update
# 指定命名策略
spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy
#指定数据库方言
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

在com.ysh下新建4个包，bean(放置持久化类)、controller(控制器)、repository(定义数据访问接口的类)、service(业务逻辑处理类)

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

/**
* 商品对象
* */
@Entity
@Table(name="tb_article")
public class Article implements Serializable{

private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String title;
private String supplier;
private Double price;
private String locality;
private Date putawayDate;
private int storage;
private String image;
private String description;
private Date createDate;
public int getId() {
  return id;
}
public void setId(int id) {
  this.id = id;
}
public String getTitle() {
  return title;
}
public void setTitle(String title) {
  this.title = title;
}
public String getSupplier() {
  return supplier;
}
public void setSupplier(String supplier) {
  this.supplier = supplier;
}
public Double getPrice() {
  return price;
}
public void setPrice(Double price) {
  this.price = price;
}
public String getLocality() {
  return locality;
}
public void setLocality(String locality) {
  this.locality = locality;
}
public Date getPutawayDate() {
  return putawayDate;
}
public void setPutawayDate(Date putawayDate) {
  this.putawayDate = putawayDate;
}
public int getStorage() {
  return storage;
}
public void setStorage(int storage) {
  this.storage = storage;
}
public String getImage() {
  return image;
}
public void setImage(String image) {
  this.image = image;
}
public String getDescription() {
  return description;
}
public void setDescription(String description) {
  this.description = description;
}
public Date getCreateDate() {
  return createDate;
}
public void setCreateDate(Date createDate) {
  this.createDate = createDate;
}

在repository包下新建一个接口，命名为ArticleRepository,让该接口继承PagingAndSortingRepository

在Spring Boot项目中，数据访问层接口无须提供实现，直接继承数据访问接口即可

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Service;

import com.ysh.pagingandsortingrepositorytest.bean.Article;
import com.ysh.pagingandsortingrepositorytest.repository.ArticleRepository;

@Service
public class ArticleService {

// 注入数据访问层接口对象
@Resource
private ArticleRepository articleRepository;

public Iterable

findAllSort(Sort sort) {
return articleRepository.findAll(sort);
}

public Page

findAll(Pageable page) {
return articleRepository.findAll(page);
}

}

⑥定义控制器类

在controller包下先新建一个控制器类，命名ArticleController

package com.ysh.pagingandsortingrepositorytest.controller;

import java.util.List;
import javax.annotation.Resource;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.ysh.pagingandsortingrepositorytest.bean.Article;
import com.ysh.pagingandsortingrepositorytest.service.ArticleService;

@RestController
@RequestMapping("/article")
public class ArticleController {

// 注入ArticleService
@Resource
private ArticleService articleService;

@RequestMapping("/sort")
public Iterable

sortArticle() {
  // 指定排序参数对象：根据id，进行降序查询
  Sort sort = new Sort(Sort.Direction.DESC, "id");
  Iterable

articleDatas = articleService.findAllSort(sort);
return articleDatas;
}

@RequestMapping("/pager")
public List

sortPagerArticle(int pageIndex) {
  // 指定排序参数对象：根据id，进行降序查询
  Sort sort = new Sort(Sort.Direction.DESC, "id");
  /**
   * 封装分页实体参数一：pageIndex表示当前查询的第几页(默认从0开始，0表示第一页) 参数二：表示每页展示多少数据，现在设置每页展示2条数据
   * 参数三：封装排序对象，根据该对象的参数指定根据id降序查询
   * */
  Pageable page = PageRequest.of(pageIndex - 1, 2, sort);
  Page

articleDatas = articleService.findAll(page);
  System.out.println("查询总页数:" + articleDatas.getTotalPages());
  System.out.println("查询总记录数:" + articleDatas.getTotalElements());
  System.out.println("查询当前第几页:" + articleDatas.getNumber() + 1);
  System.out.println("查询当前页面的记录数:" + articleDatas.getNumberOfElements());
  // 查询出的结果数据集合
  List

articles = articleDatas.getContent();
System.out.println("查询当前页面的集合:" + articles);
return articles;
}
}

⑦测试应用

启动MySql数据库，新建数据库springdatajpa数据库

新建App.java启动类

package com.ysh.pagingandsortingrepositorytest;

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

/**
* @SpringBootApplication指定这是一个 spring boot的应用程序.
*/
@SpringBootApplication
public class App
{
    public static void main( String[] args )
    {
    // SpringApplication 用于从main方法启动Spring应用的类。
        SpringApplication.run(App.class, args);
    }
}

项目启动后，JPA会在数据库中自动创建持久化类对应的tb_article表，然后打开此表，插入一些数据