IT俱乐部 Java Spring Data JPA实现排序与分页查询超详细流程讲解

Spring Data JPA实现排序与分页查询超详细流程讲解

发布: 2023年 4月 4日 460阅读

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

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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

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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;
    }
}</article></article></article>

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

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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{
    /**
     * 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

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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);
}</article></article>

接口实现类

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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 allAuthor = new ArrayList();
        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);
    }
}</article></article>

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

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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 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

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<title>显示分页查询结果</title><div class="panel panel-primary">
        <div class="panel-heading">
            <h3 class="panel-title">Spring Data JPA分页查询</h3>
        </div>
                             
                             
 
                                <ul class="pagination">
<li><a>第<span></span>页</a></li>
                                    <li><a>共<span></span>页</a></li>
                                    <li><a>共<span></span>条</a></li>
                                    <li>
                                    <a rel="external nofollow">上一页</a>
                                    </li>
                                    <li>
<a rel="external nofollow">下一页</a>
                                    </li>
                                </ul>
 
                         
</div>
            
本文收集自网络，不代表IT俱乐部立场，转载请注明出处。https://www.2it.club/code/java/6562.html
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