第6章 Spring Boot的数据访问 一、Spring Data JPA（4、@Query和@Modifying注解）
学习目标：
一、Spring Data JPA
4、@Query和@Modifying注解
学习内容：
在上两节中的查询方法必须严格按照Spring Data JPA的查询关键字命名规范进行查询方法命名。如何摆脱查询关键字和关联查询命名规范约束呢？可以通过@Query、@NamedQuery直接定义JPQL语句进行数据的访问操作。
1．@Query注解
使用@Query注解可以将JPQL语句直接定义在数据访问接口方法上，并且接口方法名不受查询关键字和关联查询命名规范约束。示例代码如下：
public interface AuthorityRepository extends JpaRepository<Authority, Integer>{
/**
* 根据用户名查询用户所拥有的权限（关联查询）
*/
@Query("select a from Authority a inner join a.userList u where u.username = ?1")
public List<Authority> findByUserListUsername(String username);
}
使用@Query注解定义JPQL语句，可以直接返回List
/**
* 根据作者id查询文章信息（标题和内容）
*/
@Query("select new Map(a.title as title, a.content as content) from Article a where a.author.id = ?1 ")
public List<Map<String, Object>> findTitleAndContentByAuthorId(Integer id);
使用@Query注解定义JPQL语句，之前的方法是使用参数位置（“?1指代的是获取方法形参列表中的第一个参数值，1代表的是参数位置，以此类推）来获取参数值。除此之外，Spring Data JPA还支持使用名称来获取参数值，使用格式为“：参数名称”。示例代码如下：
@Query("select a from Article a where a.author.aname = :aname1 and a.author.aname.id = :id1 ")
public List<Article> findArticleByAuthorAnameAndId(@Param("aname1") String aname, @Param("id1") Integer id);
2．@Modifying注解
可以使用@Modifying和@Query注解组合定义在数据访问接口方法上，进行更新查询操作。示例代码如下：
/**
* 根据作者id删除作者
*/
@Modifying
@Query("delete from Author a where a.id = ?1")
public int deleteAuthorByAuthorId(int id);
【例6-5】@Query和@Modifying注解的使用方法。
首先，为【例6-5】创建基于Spring Data JPA的Spring Boot Web应用ch6_3。ch6_3应用的数据库、pom.xml以及application.properties与ch6_2应用基本一样，不再赘述。
1）创建持久化实体类
创建名为com.ch.ch6_3.entity的包，并在该包中创建名为Author和Article的持久化实体类。
Author的具体代码如下：
package com.ch.ch6_3.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的具体代码如下：
package com.ch.ch6_3.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;
}
}
2）创建数据访问层
在com.ch.ch6_3.repository包中，创建名为AuthorRepository和ArticleRepository的接口。
AuthorRepository的代码如下：
package com.ch.ch6_3.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import com.ch.ch6_3.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）
*/
@Query("select a from Author a inner join a.articleList t where t.title like %?1%" )
public Author findAuthorByArticleListtitleContaining(String title);
/**
* 根据作者id删除作者
*/
@Modifying
@Query("delete from Author a where a.id = ?1")
public int deleteAuthorByAuthorId(int id);
}
ArticleRepository的代码如下：
package com.ch.ch6_3.repository;
import java.util.List;
import java.util.Map;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import com.ch.ch6_3.entity.Article;
public interface ArticleRepository extends JpaRepository<Article, Integer>{
/**
* 根据作者id查询文章信息（标题和内容）
*/
@Query("select new Map(a.title as title, a.content as content) from Article a where a.author.id = ?1 ")
public List<Map<String, Object>> findTitleAndContentByAuthorId(Integer id);
/**
* 根据作者名和作者id查询文章信息
*/
@Query("select a from Article a where a.author.aname = :aname1 and a.author.id = :id1 ")
public List<Article> findArticleByAuthorAnameAndId(@Param("aname1") String aname, @Param("id1") Integer id);
}
3）创建业务层
在com.ch.ch6_3.service包中，创建名为AuthorAndArticleService的接口和接口实现类AuthorAndArticleServiceImpl。
AuthorAndArticleService的代码如下：
package com.ch.ch6_3.service;
import java.util.List;
import java.util.Map;
import com.ch.ch6_3.entity.Article;
import com.ch.ch6_3.entity.Author;
public interface AuthorAndArticleService {
public List<Map<String, Object>> findTitleAndContentByAuthorId(Integer id);
public List<Article> findArticleByAuthorAnameAndId(String aname, Integer id);
public Author findAuthorByArticleListtitleContaining(String title);
public int deleteAuthorByAuthorId(int id);
}
AuthorAndArticleServiceImpl的代码如下：
package com.ch.ch6_3.service;
import java.util.List;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.ch.ch6_3.entity.Article;
import com.ch.ch6_3.entity.Author;
import com.ch.ch6_3.repository.ArticleRepository;
import com.ch.ch6_3.repository.AuthorRepository;
@Service
@Transactional
public class AuthorAndArticleServiceImpl implements AuthorAndArticleService{
@Autowired
private AuthorRepository authorRepository;
@Autowired
private ArticleRepository articleRepository;
@Override
public List<Map<String, Object>> findTitleAndContentByAuthorId(Integer id) {
return articleRepository.findTitleAndContentByAuthorId(id);
}
@Override
public List<Article> findArticleByAuthorAnameAndId(String aname, Integer id) {
return articleRepository.findArticleByAuthorAnameAndId(aname, id);
}
@Override
public Author findAuthorByArticleListtitleContaining(String title) {
return authorRepository.findAuthorByArticleListtitleContaining(title);
}
@Override
public int deleteAuthorByAuthorId(int id) {
return authorRepository.deleteAuthorByAuthorId(id);
}
}
4）创建控制器类
在com.ch.ch6_3.controller包中，创建名为TestOneToManyController的控制器类。
TestOneToManyController的代码如下：
package com.ch.ch6_3.controller;
import java.util.List;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.ch.ch6_3.entity.Article;
import com.ch.ch6_3.entity.Author;
import com.ch.ch6_3.service.AuthorAndArticleService;
@RestController
public class TestOneToManyController {
@Autowired
private AuthorAndArticleService authorAndArticleService;
@RequestMapping("/findTitleAndContentByAuthorId")
public List<Map<String, Object>> findTitleAndContentByAuthorId(Integer id){
return authorAndArticleService.findTitleAndContentByAuthorId(id);
}
@RequestMapping("/findArticleByAuthorAnameAndId")
public List<Article> findArticleByAuthorAnameAndId(String aname, Integer id){
return authorAndArticleService.findArticleByAuthorAnameAndId(aname, id);
}
@RequestMapping("/findAuthorByArticleListtitleContaining")
public Author findAuthorByArticleListtitleContaining(String title) {
return authorAndArticleService.findAuthorByArticleListtitleContaining(title);
}
@RequestMapping("/deleteAuthorByAuthorId")
public int deleteAuthorByAuthorId(int id) {
return authorAndArticleService.deleteAuthorByAuthorId(id);
}
}
5）运行
查询作者id=1的文章标题和内容：
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