SpringBoot后端开发新闻页查询+新增+编辑

新建实体

News.java:

@Entity
@Table(name = "t_news")
public class News {
    @Id  //主键标识
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;
    //懒加载
    @Basic(fetch = FetchType.LAZY)
    @Lob
    private String content;
    private String firstPicture;
    private String flag;
    private String views;

    private boolean appreciation;
    private boolean shareStatement;
    private boolean commentabled;
    private boolean published;
    private boolean recommend;
    @Temporal(TemporalType.TIMESTAMP)
    private Date createTime;
    @Temporal(TemporalType.TIMESTAMP)
    private Date updateTime;

    @ManyToOne
    private Type type;

    @ManyToOne
    private User user;

    @Transient
    private String tagIds;

    private String description;

    @ManyToMany(cascade = CascadeType.PERSIST)  //级联
    //tags名字要与Tag类中mapped by参数名相对应
    private List<Tag> tags = new ArrayList<>();

    public News(){}

    public void init(){
        this.tagIds =tagsToIds(this.getTags());
    }
	//将List<Tag>类型对象转化成"tagid1,tagid2,tagid3..."形式的String字符串
    private String tagsToIds(List<Tag> tags){
        if(!tags.isEmpty()){
            StringBuffer ids = new StringBuffer();
            boolean flag = false;
            for(Tag tag:tags){
                if(flag) {
                    ids.append(",");
                }else{
                    flag = true;
                }
                ids.append(tag.getId());
            }
            return ids.toString();
        }else {
            return tagIds;
        }
    }
	//省略get和set方法
}

Tag.java:

@Entity
@Table(name = "t_tag")
public class Tag {

    @Id  //主键标识
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @NotBlank(message = "标签名称不能为空")
    private String name;
	//mappedBy参数要与News类中List<Tag>变量名相对应
    @ManyToMany(mappedBy = "tags")
    private List<News> newsList = new ArrayList<>();

    public Tag(){}
}

Dao包新建接口

在dao包中涉及到的接口有如下两个：
NewRepository.java:

//NewRepository.java
public interface NewRepository extends JpaRepository<News,Long>, JpaSpecificationExecutor<News> {
	//只需要使用内置的方法即可
}

TagRepository.java:

//TagRepository.java
public interface TagRepository extends JpaRepository<Tag,Long> {
    Tag findByName(String name);
}

新建VO包

新建vo包，然后在其目录下新建NewQuery.java类，用来辅助对应News内容较为复杂的查询

//NewQuery.java
public class NewQuery {
    private String title;

    private Long typeId;

    private boolean recommend;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public Long getTypeId() {
        return typeId;
    }

    public void setTypeId(Long typeId) {
        this.typeId = typeId;
    }

    public boolean isRecommend() {
        return recommend;
    }

    public void setRecommend(boolean recommend) {
        this.recommend = recommend;
    }

    @Override
    public String toString() {
        return "NewQuery{" +
                "title='" + title + '\'' +
                ", typeId=" + typeId +
                ", recommend=" + recommend +
                '}';
    }
}

Service接口

在Service包中编写如下接口
NewService.java:

//NewService.java
public interface NewService {

    Page<News> listNew(Pageable pageable, NewQuery newQuery);

    News saveNews(News news);

    News getNew(Long id);

    News updateNew(News news);

}

TagService.java:

//TagService.java
public interface TagService {
    Page<Tag> ListTag(Pageable pageable);

    Tag saveTag(Tag tag);

    void deleteTag(Long id);

    Tag getTagByName(String name);

    Tag getTag(Long id);

    Tag updateTag(Long id,Tag tag);

    List<Tag> listTag();

    List<Tag> listTag(String ids);
}

然后分别编写Impl类实现对应接口

NewServiceImpl.java：

//NewServiceImpl.java
@Service
public class NewServiceImpl implements NewService {

    @Autowired
    private NewRepository newRepository;

    //新闻管理条件查询显示
    @Override
    public Page<News> listNew(Pageable pageable, NewQuery newQuery) {
        return newRepository.findAll(new Specification<News>() {
            @Override
            public Predicate toPredicate(Root<News> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                List<Predicate> predicateList = new ArrayList<>();
                //是否存在标题检索
                if(!"".equals(newQuery.getTitle())&&newQuery.getTitle()!=null){
                    predicateList.add(criteriaBuilder.like(root.<String>get("title"),"%"+newQuery.getTitle()+"%"));
                }
                //是否分类检索
                if(newQuery.getTypeId()!=null){
                    predicateList.add(criteriaBuilder.equal(root.get("type").get("id"),newQuery.getTypeId()));
                }
                //是否推荐
                if(newQuery.isRecommend()){
                    predicateList.add(criteriaBuilder.equal(root.get("recommend"),newQuery.isRecommend()));
                }
                criteriaQuery.where(predicateList.toArray(new Predicate[predicateList.size()]));
                return null;
            }
        }, (org.springframework.data.domain.Pageable) pageable);
    }

    @Override
    public News saveNews(News news) {
        if(news.getId()==null){
            news.setCreateTime(new Date());
            news.setUpdateTime(new Date());
        }
        return newRepository.save(news);
    }

    @Override
    public News getNew(Long id) {
        return newRepository.findById(id).orElse(null);
    }

    @Override
    public News updateNew(News news) {
        News news1 = newRepository.findById(news.getId()).orElse(null);
        if(news1==null){
            System.out.println("未获取更新对象");
        }
        BeanUtils.copyProperties(news,news1);
        news1.setUpdateTime(new Date());
        return newRepository.save(news1);
    }
}

TagServiceImpl.java：

//TagServiceImpl.java
@Service
public class TagServiceImpl implements TagService {

    @Autowired
    private TagRepository tagRepository;

    @Override
    public Page<Tag> ListTag(Pageable pageable) {
        return tagRepository.findAll(pageable);
    }

    @Override
    public Tag saveTag(Tag tag) {
        return tagRepository.save(tag);
    }

    @Override
    public void deleteTag(Long id) {
        tagRepository.deleteById(id);
    }

    @Override
    public Tag getTagByName(String name) {
        return tagRepository.findByName(name);
    }

    @Override
    public Tag getTag(Long id) {
        return tagRepository.findById(id).orElse(null);
    }

    @Override
    public Tag updateTag(Long id, Tag tag) {
        Tag tag1 = tagRepository.findById(id).orElse(null);
        if(tag1==null){
            System.out.println("未获得更新对象");
            return null;
        }else{
            BeanUtils.copyProperties(tag,tag1);
            return tagRepository.save(tag1);
        }

    }

    @Override
    public List<Tag> listTag() {
        return tagRepository.findAll();
    }

    @Override
    public List<Tag> listTag(String ids) {
        return tagRepository.findAllById(converToList(ids));
    }

    private List<Long> converToList(String ids){
        System.out.println("Service接受ids为："+ids);
        List<Long> list = new ArrayList<>();
        if(!"".equals(ids) && ids!=null){
            String[] idArray = ids.split(",");
            for(int i=0;i<idArray.length;i++){
                list.add(new Long(idArray[i]));
            }
        }
        return list;
    }
}

Web包

新建NewController.java类

@Controller
@RequestMapping("/admin")
public class NewController {

    private static final String INPUT = "admin/news-input";

    private static final String LIST = "admin/news";

    private static final String REDIRECT_LIST = "redirect:/admin/news";

    @Autowired
    private NewService newService;

    @Autowired
    private TypeService typeService;

    @Autowired
    private TagService tagService;

    @RequestMapping("/news")
    public String news(@PageableDefault(size = 3,sort = {"updateTime"},direction = Sort.Direction.DESC)
                               Pageable pageable, NewQuery newQuery, Model model){
        model.addAttribute("types",typeService.listType());
        model.addAttribute("page",newService.listNew(pageable,newQuery));
        return LIST;

    }

    @PostMapping("/news/search")
    public String search(@PageableDefault(size = 3,sort = {"updateTime"},direction = Sort.Direction.DESC)
                               Pageable pageable, NewQuery newQuery, Model model){
        model.addAttribute("page",newService.listNew(pageable,newQuery));
        return "admin/news::newsList";

    }

    public void setTagAndType(Model model){
        model.addAttribute("types",typeService.listType());
        model.addAttribute("tags",tagService.listTag());
    }

    @GetMapping("/news/input")
    public String input(Model model){
        setTagAndType(model);
        model.addAttribute("news",new News());
        return INPUT;
    }

    @GetMapping("/news/{id}/toUpdate")
    public String toUpdate(@PathVariable Long id,Model model){
        setTagAndType(model);
        News news = newService.getNew(id);
        news.init();
        model.addAttribute("news",news);
        return INPUT;
    }

    @PostMapping("/news/add")
    public String post(News news, RedirectAttributes attributes, HttpSession session){
        news.setUser((User) session.getAttribute("user"));
        news.setType(typeService.getType(news.getType().getId()));
        news.setTags(tagService.listTag(news.getTagIds()));
        News news1;
        if(news.getId()==null){
            news1 = newService.saveNews(news);
        }else {
            news1 = newService.updateNew(news);
        }
        if(news1==null){
            attributes.addFlashAttribute("message","操作失败");
        }else{
            attributes.addFlashAttribute("message","操作成功");
        }
        return REDIRECT_LIST;
    }
    
}

界面显示

新闻主界面：

新增界面：

发布成功：

通过分类搜索：

使用模糊搜索：

是否推荐搜索：

编辑界面：

本文地址：https://blog.csdn.net/qq_41823958/article/details/107680566