SB4.spring boot 添加数据库连接和jpa

任何的项目都是离不开数据的操作的。俗话说巧妇难做无米之粥。数据库就相当于米。

话不多说开始操作

首先，为了连接数据库需要引入jdbc支持，在pom.xml中引入如下配置：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

嵌入式数据库支持

嵌入式数据库通常用于开发和测试环境，不推荐用于生产环境。Spring Boot提供自动配置的嵌入式数据库有H2、HSQL、Derby，你不需要提供任何连接配置就能使用。

比如，我们可以在pom.xml中引入如下配置使用HSQL

<dependency>
    <groupId>org.hsqldb</groupId>
    <artifactId>hsqldb</artifactId>
    <scope>runtime</scope>
</dependency>

连接生产数据源

以MySQL数据库为例，先引入MySQL连接的依赖包，在pom.xml中加入：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.21</version>
</dependency>

在src/main/resources/application.properties中配置数据源信息

spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=dbuser
spring.datasource.password=dbpass
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

本文以Mysql为主

1.配置pom

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

2.yml配置

girl:
    age: 18
    name: "XXFF"
server:
  port: 8081
spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/hap_dev
    username: root
    password: root

3.代码结构层级如图

4.建立对象Person

package com.big.fly.object;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

/**
 * Created by Administrator on 2018/4/15.
 */
@Entity
public class Person {
    @Id
    @GeneratedValue
    private  Integer id;
    private String name;
    private Integer age;

    //必须要有构造函数
    public Person() {
    }

    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;
    }
}

5.建立

PersonController

package com.big.fly.controller;
import com.big.fly.dao.PersonRepository;
import com.big.fly.object.Person;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
/**
 * Created by 方文飞 on 2018/4/26.
 */
@RestController
public class PersonController {
    @Autowired
    PersonRepository personRepository;
    /**
     * 通过底层的jpa
     * @param age
     * @return
     */
    @GetMapping(value = "/person")
    private List<Person> personList() {
        return personRepository.findAll();
    }
    /**
     * 通过年龄来查询
     * @param age
     * @return
     */
    @GetMapping(value = "/person/age/{age}")
    public List<Person> personListByAge(@PathVariable("age") Integer age) {
        return personRepository.findByAge(age);
    }
}

6.建立Dao PersonRepository

package com.big.fly.dao;
import com.big.fly.object.Person;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
/**
 * Created by 方文飞 on 2018/4/15.
 */
public interface PersonRepository extends JpaRepository<Person,Integer> {
    /**
     *  通过年龄来查询
     *  方法名固定findByAge
     * @param age
     * @return
     */
    public List<Person> findByAge(Integer age);
}

7.运行结果如下