快速连接数据库

官方教程和 Demo：https://spring.io/guides/gs/accessing-data-mysql/

pom.xml 增加依赖：

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

初始化数据库：

create database db_example;
create user 'springuser'@'%' identified by 'ThePassword'; 
grant all on db_example.* to 'springuser'@'%';

application.properties：

# 自动建表
spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://192.168.198.155:30306/db_example
spring.datasource.username=springuser
spring.datasource.password=ThePassword
spring.datasource.driver-class-name =com.mysql.jdbc.Driver
#spring.jpa.show-sql: true

直接使用 connection：

@Controller
public class HelloControl {
  @Autowired private DataSource dataSource;
  @RequestMapping("/")
  @ResponseBody
  public String hello() throws Exception {
    Connection connection = dataSource.getConnection();
    ResultSet rs = connection.getMetaData().getTables(null, null, null, new String[] {"TABLE"});
    List<String> tables = new LinkedList<>();
    while (rs.next()) {
      tables.add(rs.getString("TABLE_NAME"));
    }
    return tables.toString();
  }
}

使用 jpa 做对象映射：

UserRepository.java

package com.example.accessingdatamysql;
import org.springframework.data.repository.CrudRepository;
import com.example.accessingdatamysql.User;
public interface UserRepository extends CrudRepository<User, Integer> {
}

User.java

package com.example.accessingdatamysql;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity // This tells Hibernate to make a table out of this class
public class User {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer id;
    private String name;
    private String email;
    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 String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
}

MainController.java：

@Controller
@RequestMapping(path = "/demo")
public class MainController {
    @Autowired
    private UserRepository userRepository;
    @PostMapping(path = "/add")
    public @ResponseBody
    String addNewUser(@RequestParam String name
            , @RequestParam String email) {
        User n = new User();
        n.setName(name);
        n.setEmail(email);
        userRepository.save(n);
        return "Saved";
    }
    @GetMapping(path = "/all")
    public @ResponseBody
    Iterable<User> getAllUsers() {
        return userRepository.findAll();
    }
}

访问：

curl -XPOST "http://localhost:8080/demo/add?name=zlj&email=zlj@qq.com"
curl http://localhost:8080/demo/all