集成Spring Data JPA

1.Spring Data JPA简介

Spring Data是一个用于简化数据访问，并支持云服务的开源框

使用完成Spring Data JPA对user表的CRUD操作。

2.步骤

1.创建工程勾选依赖

2.编写Pojo，添加注解

3.编写Dao(需要继承JpaRepository<T,ID>)

4.编写Service

5.编写Controller

6.测试

3.实现

创建工程勾选依赖

pom.xml

<?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 https://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>2.1.6.RELEASE</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

    <groupId>com.itheima</groupId>

    <artifactId>springboot-jpa</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>springboot-jpa</name>

    <description>springboot整合jpa</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>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>

    </dependencies>

    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

            </plugin>

        </plugins>

    </build>

</project>

　　编写pojo

package com.programme.pojo;

import javax.persistence.*;

/**

 * @program: springboot

 * @description: ${description}

 * @author: Mr.zw

 * @create: 2021-05-11 20:30

 **/

@Table(name = "t_user")//将实体和数据库的表关系关联起来

@Entity//标识这个对象是一个数据库的映射对象

public class User {

    /**

     * TABLE:将数据库表的主键保存在一张表中进行管理

     * SEQUENCE:Oracle数据库主键自增的方式

     * IDENTITY:使用数据库的主键自增

     *  AUTO:将主键自增交给JPA框架帮我们进行管理

     */

    @Id//标识该属性为数据库的主键

    @GeneratedValue(strategy = GenerationType.IDENTITY)//标识主键的自增的方式

    private Integer id;

    //@Column(name = "username")将数据库字段关联起来，如果名字一样则可以忽略

    private String username;

    private String password;

    private String address;

    @Override

    public String toString() {

        return "User{" +

                "id=" + id +

                ", name='" + username + '\'' +

                ", password='" + password + '\'' +

                ", address='" + address + '\'' +

                '}';

    }

    public Integer getId() {

        return id;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public String getName() {

        return username;

    }

    public void setName(String name) {

        this.username = name;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

    public String getAddress() {

        return address;

    }

    public void setAddress(String address) {

        this.address = address;

    }

}

　　编写dao接口

package com.programme.dao;

import com.programme.pojo.User;

import org.springframework.data.jpa.repository.JpaRepository;

/**

 * @program: springboot

 * @description: ${description}

 * @author: Mr.zw

 * @create: 2021-05-11 20:55

 **/

public interface UserDao extends JpaRepository<User,Integer> {

}

　　编写service接口以及实现类

package com.programme.service;

import com.programme.pojo.User;

import java.util.List;

/**

 * @program: springboot

 * @description: ${description}

 * @author: Mr.zw

 * @create: 2021-05-11 20:59

 **/

public interface UserService {

    //查询全部

    public List<User>findAll();

    //主键查询

    public User findOne(Integer id);

    //修改

    public void update(User user);

    //删除

    public void delete(Integer id);

    //新增

    public void insert(User user);

}

package com.programme.impl;

import com.programme.dao.UserDao;

import com.programme.pojo.User;

import com.programme.service.UserService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import java.util.List;

/**

 * @program: springboot

 * @description: ${description}

 * @author: Mr.zw

 * @create: 2021-05-11 21:07

 **/

@Service

public class UserServiceImpl implements UserService {

    @Autowired

    private UserDao userDao;

    //查询全部

    @Override

    public List<User> findAll() {

        return userDao.findAll();

    }

    //主键查询

    @Override

    public User findOne(Integer id) {

        return userDao.findById(id).get();//.findById（）返回选择器对象.get()返回User

    }

    //修改

    @Override

    public void update(User user) {

        //根据主键进行判断，若主键存在，执行更新，若主键不存在或者为空，执行新增

        userDao.save(user);

    }

    //删除

    @Override

    public void delete(Integer id) {

        userDao.deleteById(id);//deleteAll 删除全部

    }

    //新增

    @Override

    public void insert(User user) {

        userDao.save(user);

    }

}

　　编写controller

package com.programme.controller;

import com.programme.pojo.User;

import com.programme.service.UserService;

import org.hibernate.annotations.GeneratorType;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.*;

import java.util.List;

/**

 * @program: springboot

 * @description: ${description}

 * @author: Mr.zw

 * @create: 2021-05-11 21:18

 **/

@RestController

@RequestMapping(value = "/jpa")

public class UserController {

    @Autowired

    private UserService userService;

    //查询全部

    @PostMapping(value = "/findAll")

    public List<User> findAll(){

        return userService.findAll();

    }

    //主键查询

    @GetMapping(value = "/findById")

    public User findById(@PathVariable Integer id){

        return userService.findOne(id);

    }

    //修改

    @GetMapping(value = "/updateUser")

    public void updateUser(User user){

        userService.update(user);

    }

    //删除

    @GetMapping(value = "/deleteById")

    public void deleteById(@PathVariable Integer id){

        userService.delete(id);

    }

    //新增

    @GetMapping(value = "/insert")

    public void insert(User user){

        userService.insert(user);

    }

}

　　配置application

server:

  port: 18081

  servlet:

    context-path: /springboot-jpa

spring:

  datasource:

    driver-class-name: com.mysql.cj.jdbc.Driver

    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC

    username: root

    password: root

  jpa:

    database: mysql

    show-sql: true

    generate-ddl: true #开启建表策略

    hibernate:

      ddl-auto: validate

      #hibernate.ddl-auto，建表策略：

      #update：每次运行程序，没有表会新建表，表内有数据不会清空，只会更新

      #create：每次运行程序，没有表会新建表，表内有数据会清空

      #create-drop：每次程序结束的时候会清空表

      #validate：运行程序会校验数据与数据库的字段类型是否相同，不同会报错

总结

集成SpringDataJPA

1.Dao需要继承JpaRepository<T,ID>

2.JpaRepository<T,ID>中已经实现了增删改查,可以拿着直接使用

巴特西

集成Spring Data JPA

1.Spring Data JPA简介

2.步骤

3.实现

总结

最新文章

热门文章