SpringBoot运用Spring-Data-Jpa实现CRUD实现

下面来演示下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：

 1 server:
 2   port: 8888
 3   context-path: /
 4    
 5 helloWorld: spring Boot\u4F60\u597D
 6    
 7 msyql:
 8    jdbcName: com.mysql.jdbc.Driver
 9    dbUrl: jdbc:mysql://localhost:3306/db_diary
10    userName: root
11    password: 123456
12  
13 spring:
14    datasource:
15       driver-class-name: com.mysql.jdbc.Driver
16       url: jdbc:mysql://localhost:3306/db_book
17       username: root
18       password: passwd
19    jpa:
20      hibernate.ddl-auto: update
21      show-sql: true

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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

 1 package com.hik.dao;
 2 
 3 import org.springframework.data.jpa.repository.JpaRepository;
 4 
 5 import com.hik.entity.Book;
 6 
 7 /**
 8  * 图书Dao接口
 9  * @author jed
10  *
11  */
12 public interface BookDao extends JpaRepository<Book, Integer>{
13 
14 }

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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

  1 /*
  2  * Copyright 2008-2011 the original author or authors.
  3  *
  4  * Licensed under the Apache License, Version 2.0 (the "License");
  5  * you may not use this file except in compliance with the License.
  6  * You may obtain a copy of the License at
  7  *
  8  *      http://www.apache.org/licenses/LICENSE-2.0
  9  *
 10  * Unless required by applicable law or agreed to in writing, software
 11  * distributed under the License is distributed on an "AS IS" BASIS,
 12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 13  * See the License for the specific language governing permissions and
 14  * limitations under the License.
 15  */
 16 package org.springframework.data.repository;
 17 
 18 import java.io.Serializable;
 19 
 20 /**
 21  * Interface for generic CRUD operations on a repository for a specific type.
 22  * 
 23  * @author Oliver Gierke
 24  * @author Eberhard Wolff
 25  */
 26 @NoRepositoryBean
 27 public interface CrudRepository<T, ID extends Serializable> extends Repository<T, ID> {
 28 
 29     /**
 30      * Saves a given entity. Use the returned instance for further operations as the save operation might have changed the
 31      * entity instance completely.
 32      * 
 33      * @param entity
 34      * @return the saved entity
 35      */
 36     <S extends T> S save(S entity);
 37 
 38     /**
 39      * Saves all given entities.
 40      * 
 41      * @param entities
 42      * @return the saved entities
 43      * @throws IllegalArgumentException in case the given entity is {@literal null}.
 44      */
 45     <S extends T> Iterable<S> save(Iterable<S> entities);
 46 
 47     /**
 48      * Retrieves an entity by its id.
 49      * 
 50      * @param id must not be {@literal null}.
 51      * @return the entity with the given id or {@literal null} if none found
 52      * @throws IllegalArgumentException if {@code id} is {@literal null}
 53      */
 54     T findOne(ID id);
 55 
 56     /**
 57      * Returns whether an entity with the given id exists.
 58      * 
 59      * @param id must not be {@literal null}.
 60      * @return true if an entity with the given id exists, {@literal false} otherwise
 61      * @throws IllegalArgumentException if {@code id} is {@literal null}
 62      */
 63     boolean exists(ID id);
 64 
 65     /**
 66      * Returns all instances of the type.
 67      * 
 68      * @return all entities
 69      */
 70     Iterable<T> findAll();
 71 
 72     /**
 73      * Returns all instances of the type with the given IDs.
 74      * 
 75      * @param ids
 76      * @return
 77      */
 78     Iterable<T> findAll(Iterable<ID> ids);
 79 
 80     /**
 81      * Returns the number of entities available.
 82      * 
 83      * @return the number of entities
 84      */
 85     long count();
 86 
 87     /**
 88      * Deletes the entity with the given id.
 89      * 
 90      * @param id must not be {@literal null}.
 91      * @throws IllegalArgumentException in case the given {@code id} is {@literal null}
 92      */
 93     void delete(ID id);
 94 
 95     /**
 96      * Deletes a given entity.
 97      * 
 98      * @param entity
 99      * @throws IllegalArgumentException in case the given entity is {@literal null}.
100      */
101     void delete(T entity);
102 
103     /**
104      * Deletes the given entities.
105      * 
106      * @param entities
107      * @throws IllegalArgumentException in case the given {@link Iterable} is {@literal null}.
108      */
109     void delete(Iterable<? extends T> entities);
110 
111     /**
112      * Deletes all entities managed by the repository.
113      */
114     void deleteAll();
115 }

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再写一个BookController类

 1 package com.hik.Controller;
 2 
 3 import javax.annotation.Resource;
 4 
 5 import org.springframework.stereotype.Controller;
 6 import org.springframework.web.bind.annotation.GetMapping;
 7 import org.springframework.web.bind.annotation.PathVariable;
 8 import org.springframework.web.bind.annotation.PostMapping;
 9 import org.springframework.web.bind.annotation.RequestMapping;
10 import org.springframework.web.bind.annotation.RequestMethod;
11 import org.springframework.web.servlet.ModelAndView;
12 
13 import com.hik.dao.BookDao;
14 import com.hik.entity.Book;
15 
16 /**
17  * Book控制类
18  * @author jed
19  *
20  */
21 @Controller
22 @RequestMapping("/book")
23 public class BookController {
24     
25     @Resource
26     private BookDao bookDao;
27     
28     /**
29      * 查询所有图书
30      * @return
31      */
32     @RequestMapping(value="/list")
33     public ModelAndView list() {
34         ModelAndView mav = new ModelAndView ();
35         mav.addObject("bookList", bookDao.findAll());
36         mav.setViewName("bookList");
37         return mav;
38     }
39 
40     /**
41      * 添加图书
42      * @param book
43      * @return
44      */
45     @RequestMapping(value="/add", method=RequestMethod.POST)
46     public String add(Book book) {
47         bookDao.save(book);
48         return "forward:/book/list";
49     }
50     
51     @GetMapping(value="/preUpdate/{id}")
52     public ModelAndView preUpdate(@PathVariable("id") Integer id) {
53         ModelAndView mav = new ModelAndView();
54         mav.addObject("book", bookDao.getOne(id));
55         mav.setViewName("bookUpdate");
56         return mav;
57     }
58     
59     /**
60      * 修改图书
61      * @param book
62      * @return
63      */
64     @PostMapping(value="/update")
65     public String update(Book book) {
66         bookDao.save(book);
67         return "forward:/book/list";
68     }
69     
70     /**
71      * 删除图书
72      * @param id
73      * @return
74      */
75     @RequestMapping(value="/delete",method = RequestMethod.GET)
76     public String delete(Integer id) {
77         bookDao.delete(id);
78         return "forward:/book/list";
79     }
80 }

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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

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4 <meta charset="UTF-8">
 5 <title>图书管理页面</title>
 6 </head>
 7 <body>
 8 <a href="/bookAdd.html">添加图书</a>
 9     <table>
10         <tr>
11             <th>编号</th>
12             <th>图书名称</th>
13             <th>操作</th>
14         </tr>
15         <#list bookList as book>     
16         <tr>     
17             <td>${book.id}</td>     
18             <td>${book.bookName}</td>  
19             <td>
20                 <a href="/book/preUpdate/${book.id}">修改</a>
21                 <a href="/book/delete?id=${book.id}">删除</a>
22             </td>
23         </tr>  
24        </#list>  
25     </table>  
26 </body>
27 </html>

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bookAdd.html 图书添加页面

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4 <meta charset="UTF-8">
 5 <title>图书添加页面</title>
 6 </head>
 7 <body>
 8 <form action="book/add" method="post">
 9     图书名称：<input type="text" name="bookName"/><br/>
10     <input type="submit" value="提交"/>
11 </form>
12 </body>
13 </html>

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bookUpdate.ftl图书修改页面

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4 <meta charset="UTF-8">
 5 <title>图书修改页面</title>
 6 </head>
 7 <body>
 8 <form action="/book/update" method="post">
 9 <input type="hidden" name="id" value="${book.id}"/>
10     图书名称：<input type="text" name="bookName" value="${book.bookName}"/><br/>
11     <input type="submit" value="提交"/>
12 </form>
13 </body>
14 </html>

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浏览器请求：http://localhost:8888/book/list

进入：