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 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 getArticleList() {
return articleList;
}
public void setArticleList(List 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{
/**
* 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 findByAuthor_id(Integer id);
public List 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 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 allAt = new ArrayList();
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 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
