Spring Boot 之 MySQL数据库使用

引入依赖

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<scope>runtime</scope>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-jpa</artifactId>
</<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<scope>runtime</scope>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

JPA( Java Persistence API) 资源库，就是为 POJO （Plain Ordinary Java Object）提供持久化的标准规范，然后将 POJO 通过 ORM（Object-Relational Mapping）持久化到数据库中。

配置文件

spring:
  datasource:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/spring_boot?characterEncoding=utf8
      username: root
      password:
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
    database-platform: spring:
  datasource:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/spring_boot?characterEncoding=utf8
      username: root
      password:
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
    database-platform: org.hibernate.dialect.MySQL5Dialect

实体建模

这个实体用来与数据库中的表建立映射关系

注解	作用
@Table	指定关联的数据库的表名
@Id	唯一标识
@GeneratedValue	自动生成
@Entity	表明这是一个实体类，如果表名和实体类名相同的话，@Table可以省略

映射

Java中的对象：

package top.baimoc.mocdb.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class User {
    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private Integer age;

    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 Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        package top.baimoc.mocdb.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class User {
    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private Integer age;

    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 Integer getAge() {
        return age;
    }

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

数据库中的User表

实体的持久化

Java中用接口来实现：

package top.baimoc.mocdb.repository;

import top.baimoc.mocdb.domain.User;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface UserRepository extends JpaRepository<User, Integer>{
    public List<User> findByAgepackage top.baimoc.mocdb.repository;

import top.baimoc.mocdb.domain.User;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface UserRepository extends JpaRepository<User, Integer>{
    public List<User> findByAge(Integer age);
}

新建Controller实现增删改查

package top.baimoc.mocdb.controller;

import top.baimoc.mocdb.domain.User;
import top.baimoc.mocdb.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
public class SearchController {

    @Autowired
    private UserRepository userRepository;

    /**
     * 查询全部
     * @return
     */
    @GetMapping("/search")
    public List<User> getAll() {
        return userRepository.findAll();
    }

    /**
     * 查询单条数据
     * @param id
     * @return
     */
    @GetMapping("/search/{id}")
    public User getOne(@PathVariable("id") Integer id) {
        return userRepository.findOne(id);
    }

    /**
     * 插入一条数据
     * @param name
     * @param age
     * @return
     */
    @PostMapping("/insert")
    public User insertOne(@RequestParam("name") String name,
                          @RequestParam("age") Integer age) {
        User user = new User();
        user.setName(name);
        user.setAge(age);
        return userRepository.save(user);
    }

    /**
     * 更新一条数据
     * @param id
     * @param name
     * @param age
     * @return
     */
    @PutMapping("/updata/{id}")
    public User insertOne(@PathVariable("id") Integer id,
                          @RequestParam("name") String name,
                          @RequestParam("age") Integer age) {
        User user = new User();
        user.setId(id);
        user.setName(name);
        user.setAge(age);
        return userRepository.save(user);
    }

    /**
     * 删除一条数据
     * @param id
     */
    @DeleteMapping("/delete/{id}")
    public void deleteOne(@PathVariable("id") Integer id) {
        userRepository.delete(id);
    }

    /**
     * 根据Age查询多条数据
     * @param age
     * @return
     */
    @GetMapping("searchbyage/{age}")
    public List<User> searchByAge(@PathVariable("age") Integer age){
        package top.baimoc.mocdb.controller;

import top.baimoc.mocdb.domain.User;
import top.baimoc.mocdb.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
public class SearchController {

    @Autowired
    private UserRepository userRepository;

    /**
     * 查询全部
     * @return
     */
    @GetMapping("/search")
    public List<User> getAll() {
        return userRepository.findAll();
    }

    /**
     * 查询单条数据
     * @param id
     * @return
     */
    @GetMapping("/search/{id}")
    public User getOne(@PathVariable("id") Integer id) {
        return userRepository.findOne(id);
    }

    /**
     * 插入一条数据
     * @param name
     * @param age
     * @return
     */
    @PostMapping("/insert")
    public User insertOne(@RequestParam("name") String name,
                          @RequestParam("age") Integer age) {
        User user = new User();
        user.setName(name);
        user.setAge(age);
        return userRepository.save(user);
    }

    /**
     * 更新一条数据
     * @param id
     * @param name
     * @param age
     * @return
     */
    @PutMapping("/updata/{id}")
    public User insertOne(@PathVariable("id") Integer id,
                          @RequestParam("name") String name,
                          @RequestParam("age") Integer age) {
        User user = new User();
        user.setId(id);
        user.setName(name);
        user.setAge(age);
        return userRepository.save(user);
    }

    /**
     * 删除一条数据
     * @param id
     */
    @DeleteMapping("/delete/{id}")
    public void deleteOne(@PathVariable("id") Integer id) {
        userRepository.delete(id);
    }

    /**
     * 根据Age查询多条数据
     * @param age
     * @return
     */
    @GetMapping("searchbyage/{age}")
    public List<User> searchByAge(@PathVariable("age") Integer age){
        return userRepository.findByAge(age);
    }
}