SpringBoot 简单CRUD操作Spring-Data-JPA(四)

柔情只为你懂 2024-02-18 20:31 41阅读 0赞

Spring Data JPA 框架，主要针对的是 Spring 唯一没有简化到的业务逻辑代码，至此，开发者连仅剩的实现持久层业务逻辑的工作都省了，唯一要做的，就只是声明持久层的接口，其他都交给 Spring Data JPA 来帮你完成！

JPA(Java Persistence API)定义了一系列对象持久化的标准 目前实现这一规范的产品有Hibernate、TopLink等。

具体操作如下：

**1. 引入jpa和mysql驱动支持；** 进入pom.xml，alt+/ 进入编辑视图

![20180526154345493][]

![20180526154433631][]

**2.配置application.yml文件**

![20180526154458335][]

**3.在数据库中创建test数据库；再创建实体类，**

/**
     * 实体类
     * 
     * @author Administrator
     *
     */
    @Entity
    @Table(name = "t_student") // 指定表名
    public class Student {
    
    	@Id // 主键
    	@GeneratedValue //自动增长
    	private int id;
    	@Column(length = 20)
    	private String name;
    	@Column(length = 6)
    	private String pass;
        省略setXXX and getXXX

**4.启动Hello3Application类 (刷新就在数据库中创建这个t\_student表)**

![20180526154828753][]

**5.写底层数据继承JpaRepository**

package com.hlx.dao;
    
    import org.springframework.data.jpa.repository.JpaRepository;
    
    import com.hlx.entity.Student;
    /**
     *  数据底层  只要继承这个类就OK！
     * @author Administrator
     * 
     * JpaRepository<Student实体类, Integer主键数据类型>
     *
     */
    public interface StudentDao extends JpaRepository<Student, Integer> {
    
    }

**6.写Controller控制器**

package com.hlx.controller;
    
    import javax.annotation.Resource;
    import javax.servlet.http.HttpServletRequest;
    
    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.RequestParam;
    import org.springframework.web.servlet.ModelAndView;
    
    import com.hlx.dao.StudentDao;
    import com.hlx.entity.Student;
    
    @Controller
    @RequestMapping("/student")
    public class StudentController {
    
    	@Resource // 注入dao
    	private StudentDao studentDao;
    
    	/**
    	 * 查询所有的数据
    	 * 
    	 * @return
    	 */
    	@RequestMapping("/list")
    	public ModelAndView list() {
    		// 试图对象
    		ModelAndView view = new ModelAndView("all");
    		// 保存数据,调用查询所有的方法
    		view.addObject("students", studentDao.findAll());
    		return view;
    	}
    
    	/**
    	 * 添加数据
    	 * 
    	 * @param stu
    	 * @return
    	 */
    	@RequestMapping(value = "/add", method = RequestMethod.POST)
    	public String add(Student stu) {
    		studentDao.save(stu); // 调用添加方法
    		return "forward:/student/list"; // 转发
    	}
    
    	/**
    	 * 根据ID查找实体对象
    	 * @return
    	 */
    	@RequestMapping("/pre/{id}")
    	public ModelAndView preUpdate(@PathVariable("id") Integer id){
    		//视图对象==>到更新页面哦！
    		ModelAndView view= new ModelAndView("update");
    		//调用查询方法
    		view.addObject("student", studentDao.getOne(id));
    		return view;
    	}
    	
    	
    	/**
    	 * 根据ID更新数据
    	 * @return
    	 */
    	@PostMapping("/update")
    	public  String update(Student stu) {
    		studentDao.save(stu); // 调用添加方法，如果没有就添加，有就更新
    		return "forward:/student/list"; // 转发
    	}
    	
    	
    	/**
    	 * 根据ID删除数据
    	 * @return
    	 */
    	@GetMapping("/del")
    	public  String delete(Integer id) {
    		studentDao.deleteById(id); //调用删除方法
    		return "forward:/student/list"; // 转发
    	}
    	
    	
    
    }

**7.写页面**

**(a)add.html**

**![20180526155221898][]**

**(b)all.ftl**

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>显示学生列表信息</title>
    </head>
    <body>
    <a href="/add.html">add</a>
      <table border="1" width="75%">
        <tr>
          <td>编号</td>
          <td>姓名</td>
          <td>密碼</td>
          <td>操作</td>    
        </tr>
       <#list students as student>
       <tr>
        <td>${student.id}</td>
        <td>${student.name}</td>
        <td>${student.pass}</td>
        <td>
            <a href="/student/pre/${student.id}">update</a>   
            <a href="/student/del?id=${student.id}">delete</a>
        </td>
       </tr>
       </#list>
      
      </table>
    </body>
    </html>

**(c)update.ftl**

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
     <form action="/student/update" method="post">
           <input type="hidden" name="id" value="${student.id}"/>
           username:<input name="name" value="${student.name}"/><br/>
           password:<input  type="password" name="pass" value="${student.pass}"/><br/>
    	   <input type="submit" id="but" value="update">
    	</form>
    </body>
    </html>

工程结构如下：

![20180526155352815][]

**运行效果**

列表页面

![20180526155958181][]

添加页面

![20180526155531220][]

列表页面

![2018052615554484][]

修改页面

![20180526155612840][]

修改之后的数据

![20180526155633400][]

删除页面

![20180526155757658][]

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[20180526155612840]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/956f3aea77814dc18aa43f4fd3f12ac2.png
[20180526155633400]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/7680eb8e09694df3ba3473b4f0eba014.png
[20180526155757658]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/847cacea5c79411ba958c3219a2ff52b.png