springboot新闻管理
文章目录
- 条件查询与分页展示
- 新增
- 编辑与删除
条件查询与分页展示
1.Tag实体类新增属性，构造相应get,set函数
@ManyToMany(mappedBy = "tags")
private List<News> newsList = new ArrayList<>();
2.News中新增属性，构造相应get,set函数，改变toString函数
@ManyToMany(cascade = CascadeType.PERSIST) //级联
private List<Tag> tags = new ArrayList<>();
@Transient
private String tagIds;
private String description;
3.创建vo包，VO是指value object值对象，通常用于业务层之间的数据传递，和PO一样也是仅仅包含数据而已。一般来说，PO只能用在数据层，VO用在商业逻辑层和表示层。在vo包下创建NewsQuery类，我们利用NewsQuery类专门处理新闻管理界面的条件查询。因为我们需要通过新闻的标题、类型以及是否被推荐作为条件来查询数据库里的新闻，所以我们就利用这三个属性来组成一个查询类。
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 +
'}';
}
}
4.新建NewService接口
public interface NewService {
//新闻管理页面，组合条件查询
Page<News> listNew(Pageable pageable, NewQuery newQuery);
}
5.新建NewServiceImpl类，实现上面接口
@Service
public class NewServiceImpl implements NewService {
@Autowired
private NewRepository newRepository;
//新闻管理中的列表（包含了查询）
@Override
public Page<News> listNew(Pageable pageable, NewQuery newQuery) {
return newRepository.findAll(new Specification<News>() {
@Override
public Predicate toPredicate(Root<News> root, CriteriaQuery<?> cq, CriteriaBuilder cb) {
List<Predicate> predicates = new ArrayList<>();
if(!"".equals(newQuery.getTitle())&&newQuery.getTitle()!=null){
predicates.add(cb.like(root.<String>get("title"),"%"+newQuery.getTitle()+"%"));
}
if(newQuery.getTypeId()!=null){
predicates.add(cb.equal(root.get("type").get("id"),newQuery.getTypeId()));
}
if(newQuery.isRecommend()){
predicates.add(cb.equal(root.get("recommend"),newQuery.isRecommend()));
}
cq.where(predicates.toArray(new Predicate[predicates.size()]));
return null;
}
},pageable);
}
}
6.在TypeService和Impl中添加新的接口和实现方法
接口：
List<Type> listType();
实现方法：
@Override
public List<Type> listType() {
return typeRepository.findAll();
}
7.新建NewController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;
@GetMapping("/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";
}
}
至此，条件查询和分页展示完成
新增
1.在NewService中新加接口（包含添加，更新和删除），并在Impl中实现
接口：
News saveNew(News news);
News getNew(Long id);
News updateNew(Long id,News news);
void deleteNew(Long id);
实现：
@Override
public News saveNew(News news){
if(news.getId()==null){
news.setCreatTime(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(Long id, News news) {
News news1 = newRepository.findById(id).orElse(null);
if(news1==null){
System.out.println("未获得更新对象");
}
BeanUtils.copyProperties(news,news1);
news1.setUpdateTime(new Date());
return newRepository.save(news1);
}
@Override
public void deleteNew(Long id) {
newRepository.deleteById(id);
}
2.在NewController中写上添加功能
public void setTypeAndTag(Model model){
model.addAttribute("types",typeService.listType());
model.addAttribute("tags",tagService.listTag());
}
@GetMapping("/news/input")
public String input(Model model){
setTypeAndTag(model);
model.addAttribute("news",new News());
return INPUT;
}
@PostMapping("/news/add")
public String post(News news, RedirectAttributes attributes, HttpSession session){
System.out.println("controller接收的news为："+news);
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.saveNew(news);
}else {
news1 = newService.updateNew(news.getId(),news);
}
if(news1==null){
attributes.addFlashAttribute("message","操作失败");
}else {
attributes.addFlashAttribute("message","操作成功");
}
return REDIRECT_LIST;
}
至此，添加完成
编辑与删除
因为在写添加时，在NewService和Impl中已经将接口和实现方法写了，所以现在只需编写NewController类,实现编辑功和删除功能即可，又因为编辑和新增后的数据更新一样，所以编辑只用写页面跳转
1.在News新加一个初始函数与一个将List类型的数据转化为String类型的方法
public void init(){
this.tagIds = tagsToIds(this.getTags());
}
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;
}
}
2.编写编辑跳转和删除
@GetMapping("news/{id}/toUpdate")
public String toUpdate(@PathVariable Long id,Model model){
setTypeAndTag(model);
News news = newService.getNew(id);
news.init();
model.addAttribute("news",news);
return INPUT;
}
@GetMapping("/news/{id}/delete")
public String deleteNew(@PathVariable Long id,RedirectAttributes attributes){
newService.deleteNew(id);
attributes.addFlashAttribute("message","删除成功");
return REDIRECT_LIST;
}
至此，编辑和删除完成
运行结果如下：
1编辑：
2.删除
3.新增
4.查询
