用SpringBoot+MySql+JPA实现对数据库的增删改查和分页

使用SpringBoot+Mysql+JPA实现对数据库的增删改查和分页

JPA是Java Persistence API的简称，中文名Java持久层API，是JDK 5.0注解或XML描述对象－关系表的映射关系，并将运行期的实体对象持久化到数据库中。
使用Springboot和jpa对数据库进行操作时，能够大大减少我们的工作量，在jpa中，已经在底层封装好了增删查的功能和sql语句，可以使我们进行快速开发

项目流程

一、新建一个项目

二、配置文件

#数据源配置
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/stu?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=/stu
 
#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

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.kude.stu</groupId>
    <artifactId>kudestu</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>kudestu</name>
    <description>Demo project for Spring Boot</description>
 
    <properties>
        <java.version>1.8</java.version>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
 
        <!-- druid数据库连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper-spring-boot-starter -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.10</version>
        </dependency>
 
 
    </dependencies>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
 
</project>

三、Mysql数据库

新建一个数据库stu,创建student表和user表

四、后端实现

student实体类

package com.kude.stu.kudestu.stu.entity;
 
import javax.persistence.*;
import javax.xml.soap.Name;
 
@Entity
@Table(name = "student")
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    private int age;
    private String sex;
 
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                '}';
    }
 
    public Integer getId() {
        return id;
    }
 
    public void setId(Integer id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
 
    public String getSex() {
        return sex;
    }
 
    public void setSex(String sex) {
        this.sex = sex;
    }
 
    public Student() {
    }
}

　　user实体类

package com.kude.stu.kudestu.stu.entity;
 
import javax.persistence.*;
 
@Entity
@Table(name="user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String username;
    private String password;
 
    public User() {
    }
 
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
 
    public int getId() {
        return id;
    }
 
    public void setId(int id) {
        this.id = id;
    }
 
    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;
    }
}

StudentDao接口

package com.kude.stu.kudestu.stu.dao;
 
import com.kude.stu.kudestu.stu.entity.Student;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
 
import java.util.List;
 
public interface StudentDao extends JpaRepository<Student,Integer> {
        Student findStuById(Integer id);
        @Query(name = "findStuByName",nativeQuery = true,value = "select * from student where name=:name ")
        List<Student> findStuByName(@Param("name") String name);
}

UserDao接口

package com.kude.stu.kudestu.stu.dao;
 
import com.kude.stu.kudestu.stu.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
 
public interface UserDao extends JpaRepository<User,Integer> {
    /**
     * 根据id查询
     */
    User findUserById(int id);
 
    @Query(name = "login",nativeQuery = true,value = "select * from user where username=:username and password=:password")
    User login(@Param("username") String username,@Param("password") String password);
}

StudentService接口

package com.kude.stu.kudestu.stu.service;
 
import com.kude.stu.kudestu.stu.entity.Student;
import org.springframework.data.domain.Page;
 
import java.util.List;
 
public interface StudentService {
    Student save(Student student);
    Student update(Student student);
    void delete(Integer id);
    Student findStuById(Integer id);
    List<Student> findStuByName(String name);
 
    /**
     * 分页查询所有数据
     * @param page  当前页
     * @param pageSize  每页记录数
     * @return
     */
    Page<Student> findAll(int page,int pageSize);
 
}

StudentServiceImpl实现类

package com.kude.stu.kudestu.stu.service;
 
import com.kude.stu.kudestu.stu.dao.StudentDao;
import com.kude.stu.kudestu.stu.entity.Student;
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 Student save(Student student) {
        return studentDao.save(student);
    }
 
    @Override
    public Student update(Student student) {
        return studentDao.save(student);
    }
 
    @Override
    public void delete(Integer id) {
        studentDao.deleteById(id);
    }
 
    @Override
    public Student findStuById(Integer id) {
        return studentDao.findStuById(id);
    }
 
    @Override
    public List<Student> findStuByName(String name) {
        return studentDao.findStuByName(name);
    }
 
    @Override
    public Page<Student> findAll(int page, int pageSize) {
        Pageable pageable = PageRequest.of(page,pageSize);
        return studentDao.findAll(pageable);
    }
}

UserService接口

package com.kude.stu.kudestu.stu.service;
 
import com.kude.stu.kudestu.stu.entity.User;
 
import java.util.List;
 
public interface UserService {
    List<User> findAll();
    User findUserById(int id);
    User save(User user);
    User update(User user);
    User login(String username,String password);
}

UserServiceImpl实现类

package com.kude.stu.kudestu.stu.service;
 
import com.kude.stu.kudestu.stu.dao.UserDao;
import com.kude.stu.kudestu.stu.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
 
@Service
public class UserServiceImpl implements UserService {
 
    @Autowired
    private UserDao userDao;
 
    @Override
    public List<User> findAll() {
        return userDao.findAll();
    }
 
    @Override
    public User findUserById(int id) {
        return userDao.findUserById(id);
    }
 
    @Override
    public User save(User user) {
        return userDao.save(user);
    }
 
    @Override
    public User login(String username, String password) {
        return userDao.login(username,password);
    }
 
    @Override
    public User update(User user) {
        return null;
    }
}

StudentController类

package com.kude.stu.kudestu.stu.controller;
 
import com.kude.stu.kudestu.stu.entity.Student;
import com.kude.stu.kudestu.stu.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("/s")
public class StudentController {
    @Autowired
    private StudentService studentService;
 
    /**
     * 添加学生
     * @param student  要添加的学生对象
     * @return
     */
    @PostMapping("/add")
    public Student save(Student student){
        return studentService.save(student);
    }
 
    /**
     * 修改学生
     * @param student  要修改的学生对象
     * @return
     */
    @PostMapping("/update")
    public Student update(Student student){
        return studentService.save(student);
    }
 
    /**
     * 删除学生
     * @param id 要删除学生对象的id
     */
    @GetMapping("/del/{id}")
    public String del(@PathVariable Integer id){
        studentService.delete(id);
        return "yes";
    }
 
    /**
     * 通过姓名查询学生信息
     * @param name 要查询的学生的姓名
     * @return
     */
    @GetMapping("/findByName/{name}")
    public List<Student> findStuByName(@PathVariable String name){
        return studentService.findStuByName(name);
    }
 
    /**
     * 分页查询
     * @param page
     *
     * @return
     */
    @GetMapping("/query")
    public Page<Student> findByPage(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);
    }
}

UserController类

package com.kude.stu.kudestu.stu.controller;
 
import com.kude.stu.kudestu.stu.entity.User;
import com.kude.stu.kudestu.stu.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
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.RestController;
 
import java.util.List;
 
/**
 *处理用户信息的控制层
 * @author 张玉贤
 * */
@RestController
@RequestMapping("/user")
public class UserController {
 
    @Autowired
    private UserService userService;
 
    /**
     *查询用户的方法
     *
     */
    @RequestMapping(value = "/findAll",method = RequestMethod.POST)
    public List<User> findAll(){
        return userService.findAll();
    }
 
    /**
     * 根据id查询用户
     */
 
    @RequestMapping(value = "/findById")
    public User findUserById(int id){
        return userService.findUserById(id);
    }
 
    /**
     * 注册用户
     */
    @RequestMapping(value = "/reg",method = RequestMethod.POST)
    public User reg(User user){
        return userService.save(user);
    }
 
    /**
     * 用户登录
     */
    @PostMapping("/login")
    public User login(String username,String password){
        return userService.login(username,password);
    }
 
}