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Spring Data JPA实现排序与分页查询超详细流程讲解

作者：showswoller

在介绍Spring Data JPA的时候，我们首先认识下Hibernate。Hibernate是数据访问解决技术的绝对霸主，使用O/R映射技术实现数据访问，O/R映射即将领域模型类和数据库的表进行映射，通过程序操作对象而实现表数据操作的能力，让数据访问操作无须关注数据库相关的技术

前言

在实际开发场景中，排序与分页查询是必须的，幸运的是Spring Data JPA充分考虑了排序与分页查询的场景，为我们提供Sort类 Page接口 Pageable接口 下面通过一个实战来阐明

1、创建持久化实体类

创建名为com.ch.ch6_4.entity的包 并在该包中创建名为Article和Author的持久化实体类

代码如下

Article

package com.ch.ch6_2.entity;
import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.Lob;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.Size;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@Entity
@Table(name = "article_table")
@JsonIgnoreProperties(value = { "hibernateLazyInitializer"})
public class Article  implements Serializable{
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private int id;
	//标题
	@NotEmpty(message = "标题不能为空")
    @Size(min = 2, max = 50)
    @Column(nullable = false, length = 50) 
    private String title;
	//文章内容
    @Lob  //大对象，映射 为MySQL的Long文本类型
    @Basic(fetch = FetchType.LAZY) 
    @NotEmpty(message = "内容不能为空")
    @Size(min = 2)
    @Column(nullable = false) 
    private String content;
    //所属作者，文章与作者是多对一的关系
    @ManyToOne(cascade={CascadeType.MERGE,CascadeType.REFRESH},optional=false)
    //可选属性optional=false,表示author不能为空。删除文章，不影响用户
    @JoinColumn(name="id_author_id")//设置在article表中的关联字段(外键)
    @JsonIgnore
    private Author author;
	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 getContent() {
		return content;
	}
	public void setContent(String content) {
		this.content = content;
	}
	public Author getAuthor() {
		return author;
	}
	public void setAuthor(Author author) {
		this.author = author;
	}
}

Author

package com.ch.ch6_2.entity;
import java.io.Serializable;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@Entity
@Table(name = "author_table")
@JsonIgnoreProperties(value = { "hibernateLazyInitializer"})
public class Author implements Serializable{
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private int id;
	//作者名
	private String aname;
	//文章列表，作者与文章是一对多的关系
    @OneToMany(
    		mappedBy = "author",
    		cascade=CascadeType.ALL,
    		targetEntity = Article.class, 
    		fetch=FetchType.LAZY
    		)
    private List<Article> articleList;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getAname() {
		return aname;
	}
	public void setAname(String aname) {
		this.aname = aname;
	}
	public List<Article> getArticleList() {
		return articleList;
	}
	public void setArticleList(List<Article> articleList) {
		this.articleList = articleList;
	}
}

2、创建数据访问层

创建名为com.ch.ch6_4repository的包 并在该包中创建名为AuthorRepository的接口

package com.ch.ch6_2.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import com.ch.ch6_2.entity.Author;
public interface AuthorRepository extends JpaRepository<Author, Integer>{
	/**
	 * 根据文章标题包含的内容，查询作者（关联查询）
	 * 相当于JPQL语句：select a from Author a  inner join  a.articleList t where t.title like %?1%
	 */
	public Author findByArticleList_titleContaining(String title);
	/**
	 * 根据文章标题包含的内容，查询作者（关联查询）
	 */
	@Query("select a from Author a  inner join  a.articleList t where t.title like %?1%" )
	public Author findAuthorByArticleListtitleContaining(String title);
}

3、创建业务层

创建名为com.ch.ch6_4.service的包 并在该包中创建名为ArticleAndAuthorService的接口和接口实现类ArticleAndAuthorServiceImpl

接口

package com.ch.ch6_2.service;
import java.util.List;
import com.ch.ch6_2.entity.Article;
import com.ch.ch6_2.entity.Author;
public interface AuthorAndArticleService {
	public void saveAll();
	public List<Article> findByAuthor_id(Integer id);
	public List<Article> findByAuthor_aname(String aname);
	public Author findByArticleList_titleContaining(String title);
	public Author findAuthorByArticleListtitleContaining(String title);
}

接口实现类

package com.ch.ch6_2.service;
import java.util.ArrayList;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.ch.ch6_2.entity.Article;
import com.ch.ch6_2.entity.Author;
import com.ch.ch6_2.repository.ArticleRepository;
import com.ch.ch6_2.repository.AuthorRepository;
@Service
public class AuthorAndArticleServiceImpl implements AuthorAndArticleService{
	@Autowired
	private AuthorRepository authorRepository;
	@Autowired
	private ArticleRepository articleRepository;
	@Override
	public void saveAll() {
		//保存作者（先保存一的一端）
		Author a1 = new Author();
		a1.setAname("陈恒1");
		Author a2 = new Author();
		a2.setAname("陈恒2");
		ArrayList<Author> allAuthor = new ArrayList<Author>();
		allAuthor.add(a1);
		allAuthor.add(a2);
		authorRepository.saveAll(allAuthor);
		//保存文章
		Article at1 = new Article();
		at1.setTitle("JPA的一对多111");
		at1.setContent("其实一对多映射关系很常见111。");
		//设置关系
		at1.setAuthor(a1);
		Article at2 = new Article();
		at2.setTitle("JPA的一对多222");
		at2.setContent("其实一对多映射关系很常见222。");
		//设置关系
		at2.setAuthor(a1);//文章2与文章1作者相同
		Article at3 = new Article();
		at3.setTitle("JPA的一对多333");
		at3.setContent("其实一对多映射关系很常见333。");
		//设置关系
		at3.setAuthor(a2);
		Article at4 = new Article();
		at4.setTitle("JPA的一对多444");
		at4.setContent("其实一对多映射关系很常见444。");
		//设置关系
		at4.setAuthor(a2);//文章3与文章4作者相同
		ArrayList<Article> allAt = new ArrayList<Article>();
		allAt.add(at1);
		allAt.add(at2);
		allAt.add(at3);
		allAt.add(at4);
	public Author findByArticleList_titleContaining(String title) {
		return authorRepository.findByArticleList_titleContaining(title);
	}
	@Override
	public Author findAuthorByArticleListtitleContaining(String title) {
		return authorRepository.findAuthorByArticleListtitleContaining(title);
	}
}

4、创建控制器类

创建名为com.ch,ch6_4.controller的包 并在该包中创建名为TestSortAndPage的控制器类

package com.ch.ch6_4.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import com.ch.ch6_4.entity.Author;
import com.ch.ch6_4.service.ArticleAndAuthorService;
@Controller
public class TestSortAndPage {
	@Autowired 
	private ArticleAndAuthorService articleAndAuthorService;
	@RequestMapping("/findByAnameContaining")
	@ResponseBody
	public List<Author> findByAnameContaining(String aname, String sortColum){
		return articleAndAuthorService.findByAnameContaining(aname, sortColum);
	}
	@RequestMapping("/findAllAuthorByPage")
	/**
	 * @param page第几页
	 */
	public String findAllAuthorByPage(Integer page, Model model){
		return articleAndAuthorService.findAllAuthorByPage(page, model);
	}
}

5、创建View视图页面

创建index.html页面 部分代码如下

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>显示分页查询结果</title>
<link rel="stylesheet" th:href="@{css/bootstrap.min.css}" rel="external nofollow"  />
<link rel="stylesheet" th:href="@{css/bootstrap-theme.min.css}" rel="external nofollow"  />
</head>
<body>
	<div class="panel panel-primary">
		<div class="panel-heading">
			<h3 class="panel-title">Spring Data JPA分页查询</h3>
		</div>
							</tr>
							<tr>
							<td colspan="2" align="right">
								<ul class="pagination">
									<li><a>第<span th:text="${page}"></span>页</a></li>
									<li><a>共<span th:text="${totalPage}"></span>页</a></li>
									<li><a>共<span th:text="${totalCount}"></span>条</a></li>
									<li>
									<a th:href="@{findAllAuthorByPage(page=${page-1})}" rel="external nofollow"  th:if="${page != 1}">上一页</a>
									</li>
									<li><a th:href="@{findAllAuthorByPage(page=${page+1})}" rel="external nofollow"  th:if="${page != totalPage}">下一页</a>
									</li>
								</ul>
							</td>
						</tr>
						</tbody>
					</table>
				</div>
			</div>
		</div>
	</div>
</body>
</html>

6、运行主类 效果如下

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