idea 建立JPA项目（二）

建立Entity

package com.example.jpademo.Entity;
import lombok.Data;
import javax.persistence.*;

@Entity
@Table(name="t_book")
@Data
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    @Column(length = 100)
    private String name;
    @Column(length = 50)
    private String author;
}

建立控制器

package com.example.jpademo.Controller;

import com.example.jpademo.Dao.BookRepository;
import com.example.jpademo.Entity.Book;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;

import javax.annotation.Resource;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.List;

@Controller
@RequestMapping("/book")
public class BookController {
    @Resource
    private BookRepository bookRepository;
    private Book book;

    //查询所有图书
    @RequestMapping("/list")
    public ModelAndView list() {
        ModelAndView mav=new ModelAndView();
        mav.addObject("booklist",bookRepository.findAll());
        mav.setViewName("bookList");
        return mav;
    }

    //添加图书
    @PostMapping("/add")
    public String add(Book book) {
        bookRepository.save(book);
        //return "redirect:/book/list";
        return "forward:/book/list"; // url不变
    }

    //根据id查询book
    @RequestMapping(value = "/preUpdate/{id}")
    public ModelAndView preUpdate(@PathVariable("id")Integer id) {
        ModelAndView mav=new ModelAndView();
        mav.addObject("book",bookRepository.getById(id));
        mav.setViewName("bookUpdate");
        return  mav;
    }

    //修改图书
    @PostMapping(value = "/update")
    public String update(Book book) {
        bookRepository.save(book);
        return  "forward:/book/list";
    }

    //删除
    @GetMapping("/delete")
    public String delete(Integer id) {
        bookRepository.deleteById(id);
        return  "forward:/book/list";
    }

    //根据条件动态查询
    @RequestMapping("/list2")
    public ModelAndView list2(Book book) {
        ModelAndView mav=new ModelAndView();
        List<Book> bookList=bookRepository.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.getAuthor()!=null && !"".equals(book.getAuthor()))
                    {
                        predicate.getExpressions().add(cb.like(root.get("author"),"%"+book.getAuthor()+"%"));
                    }
                }
                return predicate;
            }
        });
        mav.addObject("book",book);
        mav.addObject("booklist",bookList);
        mav.setViewName("booklist");
        return mav;
    }

    //查询
    @ResponseBody
    @RequestMapping("/query")
    public List<Book> findByName(String name) //url中可以没有请求参数，用了@RequestParam 就必须有请求参数
    {
        return bookRepository.findByName("建筑设计");
    }

    //查询1  rul必须带参数 ， 返回的是json格式
    @ResponseBody
    @RequestMapping("/query1")
    public List<Book> findByName1(@RequestParam String name)
    {
        return bookRepository.findByName(name);
    }

    //随机显示
    @ResponseBody
    @RequestMapping("/randomlist")
    public List<Book> randomList(String name)
    {
        return bookRepository.randomList(2);
    }
}

建立接口

package com.example.jpademo.Dao;

import com.example.jpademo.Entity.Book;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

import java.util.List;

public interface BookRepository extends JpaRepository<Book,Integer> , JpaSpecificationExecutor<Book> //????
{
    @Query(value ="select * from t_book where t_book.name like %?1% ",nativeQuery = true)
    public List<Book> findByName(String name);


/*  SQL SERVER中对查询结果随机排序
    对结果记录随机排序，或随机返回X条记录，可以通过在SELECT语句中使用RAND函数来实现。但是RAND函数在查询中只生成一次，因此每一行都将得到相同的值。可以通过在ORDER BY子句中使用NEWID函数来对结果进行排序的方法来实现，代码如下：
    SELECT * FROM Northwind.Orders ORDER BY NEWID()
　　 SELECT TOP 10 * FROM Northwind.Orders  ORDER BY NEWID()
*/

    @Query(value = "select top 5 * from t_book order by  NEWID() ",nativeQuery = true) //支持
    //@Query(value = "select top ?1  * from t_book order by  NEWID() ",nativeQuery = true) //不支持 ??????
    public List<Book> randomList( Integer count);
}

在static目录建立bookAdd.html

<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/html" xmlns="http://www.w3.org/1999/html">
<head>
    <meta charset="UTF-8">
    <title>增加图书</title>
</head>
<body>
<form action="/book/add" method="post">
    图书名称：<input type="text" name="name"/><br/>
    图书作者：<input type="test" name="author"/><br/>
    <input type="submit" value="提交"/>
</form>
</body>
</html>

在templates目录建立bookList.html

<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml"  xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>图书管理</title>
</head>
<body>
<a href="/bookAdd.html">添加</a></br>
<table>
    <tr>
        <th>编号</th>
        <th>图书名称</th>
        <th>图书作者</th>
        <th>操作</th>
    </tr>
</table>
<p th:each="book:${booklist}">
    <tr>
        <td th:text="${book.id}"></td>
        <td th:text="${book.name}"></td>
        <td th:text="${book.author}"></td>
        <td>
            <a th:href="'/book/preUpdate/'+${book.id}">修改</a>
            <a th:href="'/book/delete?id='+${book.id}">删除</a>
        </td>
    </tr>

</p>
</body>
</html>

在templates建立bookUpdate.html

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>图书修改</title>
</head>
<body>

<!--th:action="@{/book/update}" 或 th:action="'/book/update'"都正确，  th:action="/book/update"错误，但是taction="'/book/update"正确-->
<form th:action="@{/book/update}" th:method="post">
    <input th:type="hidden" th:name="id" th:value="${book.id}"/>
    图书名称：<input th:type="text" th:name="name"   th:value="${book.name}"/><br/>
    图书作者：<input th:type="text" th:name="author" th:value="${book.author}"/><br/>
    <input th:type="submit" th:value="提交"/>
</form>
</body>
</html>