一、pom.xml添加依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency>
二、application.properties添加数据库配置
spring.datasource.url=jdbc:mysql://localhost:3306/spring_boot_db?serverTimezone=GMT%2B8spring.datasource.username=rootspring.datasource.password=123456spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driverspring.jpa.properties.hibernate.hbm2ddl.auto=updatespring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialectspring.jpa.show-sql= true
如果数据库连接写成spring.datasource.url=jdbc:mysql://localhost:3306/spring_boot ，由于MySQL版本的问题，可能会有以下的错误，在后面加上“?serverTimezone=GMT%2B8”，设置下时区，解决。
设置驱动，spring.datasource.driver-class-name=com.mysql.jdbc.Driver会有下面红色的警告信息。说的是com.mysql.jdbc.Driver'被弃用了，要使用新的驱动com.mysql.cj.jdbc.Driver’，改成com.mysql.cj.jdbc.Driver'以后一切正常。 Loading classcom.mysql.jdbc.Driver’. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
三、添加实体类
@Entity代表这是一个实体类，@Table(name=”user”)用来对应数据库中的use表，@Id用来表达主键，@Column(name=”id”)表明一个id属性。
@GeneratedValue使主键自增，如果还有疑问，可参考@GeneratedValue源码解析。
package com.example.demo.domain;import java.io.Serializable;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "user")public class User implements Serializable {private static final long serialVersionUID = 1L;@Id@GeneratedValueprivate Long id;@Column(name = "username")private String userName;@Column(name = "password")private String passWord;public User() {super();}public User(String userName, String passWord) {super();this.userName = userName;this.passWord = passWord;}public Long getId() {return id;}public void setId(Long 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;}}
四、添加Dao
Dao层主要用来实现对数据库的增、删、查、改。 dao只要继承JpaRepository类就可以，几乎可以不用写方法，可以根据方法名来自动的生产SQL，比如findByUserName 会自动生产一个以 userName 为参数的查询方法。
package com.example.demo.dao;import org.springframework.data.jpa.repository.JpaRepository;import com.example.demo.domain.User;public interface UserRepository extends JpaRepository<User, Long> {User findByUserName(String userName);}
五、添加Controller
package com.example.demo.controller;import java.util.ArrayList;import java.util.List;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import org.springframework.web.bind.annotation.RestController;import com.example.demo.dao.UserRepository;import com.example.demo.domain.User;@RestController@RequestMapping("user")public class UserController {@Autowiredprivate UserRepository userRepository;@RequestMapping("/getAllUser")@ResponseBodypublic List<User> findAll() {List<User> list = new ArrayList<User>();list = userRepository.findAll();return list;}@RequestMapping("/getByUserName")@ResponseBodypublic User getByUserName(String userName) {User user = userRepository.findByUserName(userName);return user;}}
