SpringBoot+Jpa实现CURD

一、项目创建

1.新建项目
开发工具使用IDEA，数据库用MYSQL5.7，Maven3.5.3导入依赖jar，JDK1.8版本.

SpringBoot+Jpa实现CURD
2.MYSQL用5.1.38驱动:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.38</version>
</dependency>

3.配置druid数据库连接池

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.10</version>
</dependency>

4.配置application.properties文件
SpringBoot+Jpa实现CURD

#数据源配置
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/student?useSSL=false&useUnicode=true&characterEncoding=utf-8&autoReconnect=true&serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.initialSize=20
spring.datasource.minIdle=50
spring.datasource.maxActive=500


#上下文配置
server.port=8888
server.servlet.context-path=/jixian


#配置jpa
#帮我们自动生成表结构
spring.jpa.properties.hibernate.hbm2ddl.auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.show-sql= true

spring.jpa.properties.hibernate.enable_lazy_load_no_trans=true

SpringBoot+Jpa实现CURD
4.先写一个控制层测试环境是否搭建成功
建一个controller包
代码如下：

package com.jixian.test.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/test")
public class StudentController {
    @RequestMapping("/hello")
    public void hello(){
        System.out.println("hello");
    }

}

然后进行下一步：
SpringBoot+Jpa实现CURD

打开浏览器在地址栏输入
SpringBoot+Jpa实现CURD
看到控制台输出hello，环境就搭建成功了。

二、编码

1.建表
SpringBoot+Jpa实现CURD
创建一个t_stu表，id为主键。
2.写实体
分为如下几层:

定义一个Students实体类:
在实体类上用@Entity注解来表明实体.
@Table(name = “t_stu”)映射数据库表,name为数据库的表名。
@Id注解定义主键
@GeneratedValue(strategy = GenerationType.IDENTITY)定义主键自增

package com.kude.demo.entity;

import javax.persistence.*;

@Entity
@Table(name = "t_stu")
public class Students {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String name;
    private String sex;
    private int age;
    private String username;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Students(int id, String name, String sex, int age, String username, String password) {
        this.id = id;
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.username = username;
        this.password = password;
    }

    public Students() {
    }

    @Override
    public String toString() {
        return "Students{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", sex='" + sex + '\'' +
                ", age=" + age +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

3.定义Dao接口继承JpaRepository:
JpaRepository接口有简单的增删改查方法，通过继承可以使用相应的方法

public interface StudentDao extends JpaRepository<Students,Integer> {
    Students findStuById(int id);
    @Query(name = "findByName",nativeQuery = true,value =
            "select * from t_stu where name = :name")
    List<Students> findByName(@Param("name")String name);
}

SpringBoot+Jpa实现CURD
@Query注解用来自定义SQL语句，name是方法名，nativeQuery = true时，可以执行原生sql语句，所谓原生sql，也就是说这段sql拷贝到数据库中，然后把参数值给一下就能运行了。
value是自定义的SQL语句。
@Param用来参数绑定
SpringBoot+Jpa实现CURD

4.定义Service接口并实现:
StudentService接口代码如下:

package com.kude.demo.service;

import com.kude.demo.entity.Students;
import org.springframework.data.domain.Page;

import java.util.List;

public interface StudentService {
    Students findById(int id);
    void delete(int id);
    Students save(Students students);
    Page<Students> findAll(int page,int pagesize);
    Students update(Students students);
    List<Students> findStuByName(String name);
}

StudentServiceImpl来实现代码如下:

package com.kude.demo.service;

import com.kude.demo.dao.StudentDao;
import com.kude.demo.entity.Students;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;

import java.util.List;
@Service
public class StudentServiceImpl implements StudentService {
    @Autowired
    private StudentDao studentDao;
    @Override
    public Students findById(int id) {

        return studentDao.findStuById(id);
    }

    @Override
    public void delete(int id) {
      studentDao.deleteById(id);
    }

    @Override
    public Students save(Students students) {
        return  studentDao.save(students);
    }

    @Override
    public Page<Students> findAll(int page, int pagesize) {
       Pageable pageable = PageRequest.of(page,pagesize);
        return studentDao.findAll(pageable);
    }

    public List<Students> findAll(){
        return  studentDao.findAll();
    }

    @Override
    public Students update(Students students) {

        return studentDao.save(students);
    }

    @Override
    public List<Students> findStuByName(String name) {
        return studentDao.findByName(name);
    }
}

@Service定义Service层，StudentServiceImpl用@Service
@Autowired自动为属性赋值

@Autowired
    private StudentDao studentDao;

5.定义StudentController控制层:
@RestController标注controller控制层
@RestController注解，相当于@[email protected]两个注解的结合，返回json数据不需要在方法前面加@ResponseBody注解了，但使用@RestController这个注解，就不能返回jsp,html页面，视图解析器无法解析jsp,html页面。

@ResponseBody 表示该方法的返回结果直接写入 HTTP response body 中，一般在异步获取数据时使用【也就是AJAX】，在使用 @RequestMapping后，返回值通常解析为跳转路径，但是加上 @ResponseBody 后返回结果不会被解析为跳转路径，而是直接写入 HTTP response body 中。比如异步获取 json 数据，加上 @ResponseBody 后，会直接返回 json 数据。@RequestBody 将 HTTP 请求正文插入方法中，使用适合的 HttpMessageConverter 将请求体写入某个对象。
@RequestMapping标注请求映射的路径
value是路径名，method 是请求方式get/post
@PostMapping注解是Post请求映射
@GetMapping为Get请求映射

package com.kude.demo.controller;

import com.kude.demo.entity.Students;
import com.kude.demo.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.web.bind.annotation.*;


import javax.servlet.http.HttpServletResponse;
import java.util.List;


@RestController
@RequestMapping("/stu")
public class StudentController {
    @Autowired
    private StudentService studentService;

    @PostMapping("/reg")
    public Students reg(Students students){
      return  studentService.save(students);
    }
    @GetMapping("/findAll")
    public Page<Students> findAll(Integer page, HttpServletResponse response){
        response.setHeader("Access-Control-Allow-Origin","*");
       if(page==null||page<=0){
           page = 0;
       }else {
           page -= 1;
       }
        return  studentService.findAll(page,5);
    }
    @GetMapping("/delete/{id}")
    public String delete(@PathVariable int id){
        studentService.delete(id);
        return "sucesss";
    }

    /**
     *
     * @param students
     * @return
     */
    @PostMapping("/update")
    public Students update(Students students){
        return studentService.save(students);
    }
    @GetMapping("/select/{id}")
    public  Students select(@PathVariable int id)throws Exception{
       return studentService.findById(id);
    }
    @GetMapping("/findByName/{name}")
    public List<Students> findByName(@PathVariable String name){
        return studentService.findStuByName(name);
    }

}

在默认的情况下，Spring会对@PathVariable注解的变量进行自动赋值.
前端页面:
index.html:

<!DOCTYPE html>
<html>
   <head>
      <meta charset="utf-8">
      <title></title>
      <script src="js/jquery.js" type="text/javascript" charset="utf-8"></script>
      
      <script type="text/javascript">
         
         var page = 1;
         var tp = 0;
         
         $(function(){
            showData();
         });
         
         function upPage(){
            if(page>1){
               page--;
               showData();
            }
            
         }
         
         function downPage(){
            if(page<tp){
               page++;
               showData();
            }
            
         }
         
         function showData(){
            $.ajax({
               url:'http://localhost:8888/jixian/stu/findAll?page='+page,
               success:function(result){
                  
                  var rel = result.content;
                  tp = result.totalPages;
                  
                  var htmlStr = "<table width='80%' algin='center' border='1'>"+
                           "<tr><th>ID</th><th>姓名</th><th>年龄</th><th>性别</th><th>用户名</th><th>密码</th><th>操作</th></tr>";
                  
                  for(var i=0;i<rel.length;i++){
                     var stu = rel[i];
                     htmlStr += "<tr><td>"+stu.id+"</td><td>"+stu.name+"</td><td>"+stu.age+"</td><td>"+stu.sex+"</td>"+"<td>"+stu.username+"</td>"+"<td>"+stu.password+"</td>"+
                     "<td><a href='http://localhost:8888/jixian/stu/select/"+stu.id+"'>编辑</a>&nbsp;<a href='http://localhost:8888/jixian/stu/delete/"+stu.id+"'>删除</a></td></tr>";
                  }
                  
                  htmlStr += "</table>";
                  
                  $("#show").html(htmlStr);
               }
            });
         }
         
      </script>
      
   </head>
   <body>
      
      <h1 style="text-align: center;">学生管理系统</h1>
      <hr>
      <a href="add.html">添加学生</a>
      
      <div id="show">
         
      </div>
      
      <a href="javascript:upPage();">上一页</a>&nbsp;&nbsp;<a href="javascript:downPage();">下一页</a>
      
   </body>
</html>

add.html

<!DOCTYPE html>
<html>
   <head>
      <meta charset="utf-8">
      <title></title>
   </head>
   <body>
      <h1>添加学生</h1>
      <hr>
      <form action="http://localhost:8888/kude/stu/reg" method="post">
         <p>
            姓名：<input type="text" name="name" />
         </p>
         <p>
            年龄：<input type="text" name="age" />
         </p>
         <p>
            性别：
            <input type="radio" name="sex" value="男"  checked />男
            <input type="radio" name="sex" value="女" />女
         </p>
         <p>
            用户名:<input type="text" name="username">
         </p>
         <p>
             密码:<input type="password" name="password">
         </p>
         <p>
            <input type="submit" value="保存" />
         </p>
      </form>
   </body>
</html>

（一）数据的分页
直接调用Dao接口的父类JPA接口的分页方法
1.在Service接口层定义：

Page<Students> findAll(int page, int pagesize);

2.Service实现：

public Page<Students> findAll(int page, int pagesize) {
   Pageable pageable = PageRequest.of(page,pagesize);
    return studentDao.findAll(pageable);
}

3.Controller层：

@GetMapping("/findAll")
public Page<Students> findAll(Integer page, HttpServletResponse response){
    response.setHeader("Access-Control-Allow-Origin","*");
   if(page==null||page<=0){
       page = 0;
   }else {
       page -= 1;
   }
    return  studentService.findAll(page,5);
}

SpringBoot+Jpa实现CURD

（二)解决跨域请求

 response.setHeader("Access-Control-Allow-Origin","*");

效果展示:
SpringBoot+Jpa实现CURD
添加学生：

SpringBoot+Jpa实现CURD

一、项目创建

二、编码

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