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：

server:
  port: 8888
  context-path: /
   
helloWorld: spring Bootu4F60u597D
   
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">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/${book.id}">修改</a>
                <a href="/book/delete?id=${book.id}">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！