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  • Spring Boot jpa Service层实现代码

    package com.fei.service.impl;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.persistence.criteria.CriteriaBuilder;
    import javax.persistence.criteria.CriteriaQuery;
    import javax.persistence.criteria.Predicate;
    import javax.persistence.criteria.Root;
    
    import org.springframework.beans.BeanUtils;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.domain.Page;
    import org.springframework.data.domain.Pageable;
    import org.springframework.data.jpa.domain.Specification;
    import org.springframework.stereotype.Service;
    
    import com.fei.NotFoundException;
    import com.fei.po.Blog;
    import com.fei.po.Type;
    import com.fei.repository.BlogRepository;
    import com.fei.service.BlogService;
    
    /**
     * Created by zxf on 2019年10月3日
     */
    @Service
    public class BlogServiceImpl implements BlogService {
    
    	@Autowired
    	private BlogRepository blogRepository;
    
    	/**
    	 * 根据id查询一条博客
    	 * 
    	 * @param id
    	 * @return
    	 */
    	@Override
    	public Blog getBlog(Long id) {
    		return blogRepository.findById(id).get();
    	}
    
    	/**
    	 * 多条件动态查询博客列表
    	 * 
    	 * @param pageable
    	 * @param blog
    	 * @return
    	 */
    	@Override
    	public Page<Blog> listBlog(Pageable pageable, Blog blog) {
    		return blogRepository.findAll(new Specification<Blog>() {
    
    			@Override
    			public Predicate toPredicate(Root<Blog> root, CriteriaQuery<?> cq, CriteriaBuilder cb) {
    				List<Predicate> predicates = new ArrayList<>();
    
    				String title = blog.getTitle();
    				if (!"".equals(title) && title != null) {
    					predicates.add(cb.like(root.<String>get("title"), "%" + title + "%"));
    				}
    
    				Long id = blog.getType().getId();
    				if (id != null) {
    					predicates.add(cb.equal(root.<Type>get("type").get("id"), id));
    				}
    
    				boolean isRecommend = blog.isRecommend();
    				if (isRecommend) {
    					predicates.add(cb.equal(root.<Boolean>get("recommend"), isRecommend));
    				}
    
    				cq.where(predicates.toArray(new Predicate[predicates.size()]));
    				return null;
    			}
    		}, pageable);
    	}
    
    	/**
    	 * 保存一条博客
    	 * 
    	 * @param blog
    	 * @return
    	 */
    	@Override
    	public Blog saveBlog(Blog blog) {
    		return blogRepository.save(blog);
    	}
    
    	/**
    	 * 更新一条博客,先根据id查出结果回显
    	 * 
    	 * @param id
    	 * @param blog
    	 * @return
    	 */
    	@Override
    	public Blog updateBlog(Long id, Blog blog) {
    		Blog b = blogRepository.findById(id).get();
    		if (b == null) {
    			throw new NotFoundException("你要更新的博客不存在!");
    		}
    
    		BeanUtils.copyProperties(b, blog);
    		return blogRepository.save(blog);
    	}
    
    	/**
    	 * 根据id删除一条博客
    	 * 
    	 * @param id
    	 */
    	@Override
    	public void deleteBlog(Long id) {
    		blogRepository.deleteById(id);
    	}
    
    }
    
    
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  • 原文地址:https://www.cnblogs.com/zxfei/p/11621124.html
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