第9讲 9.3 动态查询specification

1，BookDao 添加继承，JapSpecificationExecutor<Book>,

ps:本例中两个接口可以忽略

package com.cruise.dao;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Query;

import com.cruise.entity.Book;

public interface BookDao extends JpaRepository<Book, Integer>,JpaSpecificationExecutor<Book>{

   @Query("select b from Book b where b.name like %?1%")
   public List<Book> queryByName(String bookName);

   @Query(value="select * from t_book order by RAND() limit ?1",nativeQuery=true)
   public List<Book> randomList(Integer num);
}

2, Controller写方发，写一个内部类

注意当new Specification<Book>() {}导包：import org.springframework.data.jpa.domain.Specification;

@RequestMapping("/list2")
public ModelAndView list2(Book book){
       ModelAndView mav = new ModelAndView();
       List<Book> bookList = bookDao.findAll(new Specification<Book>() {

           @Override
           public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
               Predicate predicate = cb.conjunction();
               if(book!=null){
                   if(book.getName()!=null && !"".equals(book.getName())){
                       predicate.getExpressions().add(cb.like(root.get("name"), "%"+book.getName()+"%"));
                   }
               }
               if(book!=null){
                   if(book.getAuthor()!=null && !"".equals(book.getAuthor())){
                       predicate.getExpressions().add(cb.like(root.get("author"), "%"+book.getAuthor()+"%"));
                   }
               }
               return predicate;
           }
       });
       mav.addObject("bookList", bookList);
       mav.setViewName("bookList");
       return mav;
   }
       mav.addObject("bookList", bookList);
       mav.setViewName("bookList");
       return mav;
}

3，在bookAdd.ftl 中添加查询前台添加：form表单，

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书列表</title>
</head>
<body>
<a href="/bookAdd.html">添加</a>
<form action="/book/list2" method="post">
图书名称：<input type="text" name="name"/>   图书作者：<input type="text" name="author"/><br/>
<input type="submit" value="查询"/>
</form>
<table>
   <tr>
       <th>编号</th>
       <th>名称</th>
       <th>作者</th>
       <th>操作</th>
   </tr>
   <#list bookList as book>
   <tr>
       <td>${book.id}</td>
       <td>${book.name}</td>
       <td>${book.author}</td>
       <td>
           <a href="/book/preupdate/${book.id}">修改</a>
           <a href="/book/delete?id=${book.id}">删除</a>
       </td>
   </tr>
   </#list>
</table>
</body>
</html>

4，测试

第9讲 9.3 动态查询specification

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