Spring Data jpa 基本crud操作

实体类

@Entity 实体表

@Id 主键 @GeneratedValue自增

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="t_book")
public class Book {

	@Id
	@GeneratedValue
	private Integer id;
	
	@Column(length=100)
	private String name;
	
	@Column(length=50)
	private String author;
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getAuthor() {
		return author;
	}
	public void setAuthor(String author) {
		this.author = author;
	}
	
	
}

application.yml 

yml格式配置数据源

ddl-auto 自动更新

server: 
    port: 80
    context-path: /

spring: 
    datasource: 
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/db_book
      username: root
      password: 123456
    jpa: 
      hibernate:
        ddl-auto: update
      show-sql: true

spring jpa接口

实现JpaRepository 参数book泛型和主键的数据类型

@Query 自定义查询

nativeQuery 本地查询随机查询

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

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

	@Query("select b from Book b where b.name like %?1%")
	public List<Book> findByName(String name);
	
	@Query(value="select * from t_book order by RAND() limit ?1",nativeQuery=true)
	public List<Book> randomList(Integer n);
	
}

直接注入BookDao 

findAll为jpa内部封装的方法

@PostMapping指定了为post方法

Specification 不确定传入参数个数类型，动态判断拼接sql 要继承JpaSpecificationExecutor接口

toPredicate方法动态拼接条件

package com.java1234.controller;

import java.util.List;

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 org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;

/**
 * 图书控制器
 * @author Administrator
 *
 */
@Controller
@RequestMapping("/book")
public class BookController {

	@Resource
	private BookDao bookDao;
	
	/**
	 * 查询所有图书
	 * @return
	 */
	@RequestMapping("/list")
	public ModelAndView list(){
		ModelAndView mav=new ModelAndView();
		mav.addObject("bookList", bookDao.findAll());
		mav.setViewName("bookList");
		return mav;
	}
	
	/**
	 * 根据条件动态查询
	 * @param book
	 * @return
	 */
	@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.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;
	}
	
	/**
	 * 添加图书
	 * @param book
	 * @return
	 */
	@RequestMapping(value="/add",method=RequestMethod.POST)
	public String add(Book book){
		bookDao.save(book);
		return "forward:/book/list";
	}
	
	/**
	 * 根据id查询book实体
	 * @param id
	 * @return
	 */
	@RequestMapping("/preUpdate/{id}")
	public ModelAndView preUpdate(@PathVariable("id")Integer id){
		ModelAndView mav=new ModelAndView();
		mav.addObject("book", bookDao.getOne(id));
		mav.setViewName("bookUpdate");
		return mav;
	}
	
	/**
	 * 修改图书
	 * @param book
	 * @return
	 */
	@PostMapping(value="/update")
	public String update(Book book){
		bookDao.save(book);
		return "forward:/book/list";
	}
	
	@GetMapping("/delete")
	public String delete(Integer id){
		bookDao.delete(id);
		return "forward:/book/list";
	}
	
	@ResponseBody
	@GetMapping("/queryByName")
	public List<Book> queryByName(){
		return bookDao.findByName("编程");
	}
	
	@ResponseBody
	@GetMapping("/randomList")
	public List<Book> randomList(){
		return bookDao.randomList(2);
	}
}

bookList.ftl

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书管理</title>
</head>
<body>
<a href="/bookAdd.html">添加</a><br/>
<form method="post" action="/book/list2">
	图书名称：<input type="text" name="name" />&nbsp;
	图书作者：<input type="text" name="author" />&nbsp;
	<input type="submit" value="搜索"/>
</form>
<table>
	<tr>
		<th>编号</th>
		<th>图书名称</th>
		<th>图书作者</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>

bookAdd.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</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="text" name="author"/><br/>
	<input type="submit" value="提交"/>
</form>
</body>
</html>

bookUpdate.ftl

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书修改</title>
</head>
<body>
<form action="/book/update" method="post">
	<input type="hidden" name="id" value="${book.id}"/>
	图书名称：<input type="text" name="name" value="${book.name}"/><br/>
	图书作者：<input type="text" name="author" value="${book.author}"/><br/>
	<input type="submit" value="提交"/>
</form>
</body>
</html>