SpringBoot使用Spring-Data-Jpa实现CRUD操作

本文演示了SpringBoot下,实用Spring-Data-Jpa来实现CRUD操作，视图层采用Freemarker

这里我们先把application.properties修改成application.yml 主流格式

内容也改成yml规范格式：

server:
 port: 8888
 context-path: /

helloWorld: spring Boot\u4F60\u597D

msyql:
 jdbcName: com.mysql.jdbc.Driver
 dbUrl: jdbc:mysql://localhost:3306/db_diary
 userName: root
 password: 123456

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

yml格式有个注意点 冒号后面一定要加个空格

还有我们把context-path改成/方便开发应用

先写一个BookDao接口

package com.hik.dao;

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

import com.hik.entity.Book;

/**
 * 图书Dao接口
 * @author jed
 *
 */
public interface BookDao extends JpaRepository<Book, Integer>{

}

要求实现JpaRepository，JpaRepository是继承PagingAndSortingRepository，PagingAndSortingRepository是继承CrudRepository。CrudRepository实现了实体增删改查操作

/*
 * Copyright 2008-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.data.repository;

import java.io.Serializable;

/**
 * Interface for generic CRUD operations on a repository for a specific type.
 *
 * @author Oliver Gierke
 * @author Eberhard Wolff
 */
@NoRepositoryBean
public interface CrudRepository<T, ID extends Serializable> extends Repository<T, ID> {

 /**
  * Saves a given entity. Use the returned instance for further operations as the save operation might have changed the
  * entity instance completely.
  *
  * @param entity
  * @return the saved entity
  */
 <S extends T> S save(S entity);

 /**
  * Saves all given entities.
  *
  * @param entities
  * @return the saved entities
  * @throws IllegalArgumentException in case the given entity is {@literal null}.
  */
 <S extends T> Iterable<S> save(Iterable<S> entities);

 /**
  * Retrieves an entity by its id.
  *
  * @param id must not be {@literal null}.
  * @return the entity with the given id or {@literal null} if none found
  * @throws IllegalArgumentException if {@code id} is {@literal null}
  */
 T findOne(ID id);

 /**
  * Returns whether an entity with the given id exists.
  *
  * @param id must not be {@literal null}.
  * @return true if an entity with the given id exists, {@literal false} otherwise
  * @throws IllegalArgumentException if {@code id} is {@literal null}
  */
 boolean exists(ID id);

 /**
  * Returns all instances of the type.
  *
  * @return all entities
  */
 Iterable<T> findAll();

 /**
  * Returns all instances of the type with the given IDs.
  *
  * @param ids
  * @return
  */
 Iterable<T> findAll(Iterable<ID> ids);

 /**
  * Returns the number of entities available.
  *
  * @return the number of entities
  */
 long count();

 /**
  * Deletes the entity with the given id.
  *
  * @param id must not be {@literal null}.
  * @throws IllegalArgumentException in case the given {@code id} is {@literal null}
  */
 void delete(ID id);

 /**
  * Deletes a given entity.
  *
  * @param entity
  * @throws IllegalArgumentException in case the given entity is {@literal null}.
  */
 void delete(T entity);

 /**
  * Deletes the given entities.
  *
  * @param entities
  * @throws IllegalArgumentException in case the given {@link Iterable} is {@literal null}.
  */
 void delete(Iterable<? extends T> entities);

 /**
  * Deletes all entities managed by the repository.
  */
 void deleteAll();
}

再写一个BookController类

package com.hik.Controller;

import javax.annotation.Resource;

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.servlet.ModelAndView;

import com.hik.dao.BookDao;
import com.hik.entity.Book;

/**
 * Book控制类
 * @author jed
 *
 */
@Controller
@RequestMapping("/book")
public class BookController {

 @Resource
 private BookDao bookDao;

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

 @GetMapping(value="/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";
 }

 /**
  * 删除图书
  * @param id
  * @return
  */
 @RequestMapping(value="/delete",method = RequestMethod.GET)
 public String delete(Integer id) {
  bookDao.delete(id);
  return "forward:/book/list";
 }
}

实现了 CRUD

这里的@GetMapping(value="xxx") 类似  @RequestMapping(value="xxx",method=RequestMethod.GET)

以及@PostMapping(value="xxx") 类似  @RequestMapping(value="xxx",method=RequestMethod.POST)

bookList.ftl 展示数据

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书管理页面</title>
</head>
<body>
<a href="/bookAdd.html" rel="external nofollow" >添加图书</a>
 <table>
  <tr>
   <th>编号</th>
   <th>图书名称</th>
   <th>操作</th>
  </tr>
  <#list bookList as book>
  <tr>
   <td>${book.id}</td>
   <td>${book.bookName}</td>
   <td>
    <a href="/book/preUpdate/${book.id}" rel="external nofollow" >修改</a>
    <a href="/book/delete?id=${book.id}" rel="external nofollow" >删除</a>
   </td>
  </tr>
  </#list>
 </table>
</body>
</html>

bookAdd.html 图书添加页面

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书添加页面</title>
</head>
<body>
<form action="book/add" method="post">
 图书名称：<input type="text" name="bookName"/><br/>
 <input type="submit" value="提交"/>
</form>
</body>
</html>

bookUpdate.ftl图书修改页面

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

浏览器请求：http://localhost:8888/book/list

进入：

点击 “添加图书”：

进入：

我们随便输入名称，点击“提交”，

选择刚才添加的测试图书，进行修改

转发执行到列表页面，然后点“修改”，

进入修改页面，修改下名称，点击“提交”，

选择测试图书，进行删除操作

再次转发到列表页面，我们点击“删除”，

删掉数据后，再次转发到列表页面；

OK完成！

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