跟着官方Guide学习Spring Boot(一):Accessing-data-mysql

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mysql> create database db_example; -- Creates the new database
mysql> create user 'springuser'@'%' identified by 'ThePassword'; -- Creates the user
mysql> grant all on db_example.* to 'springuser'@'%'; -- Gives all privileges to the new user on the newly created database

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spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://${MYSQL_HOST:localhost}:3306/db_example
spring.datasource.username=springuser
spring.datasource.password=ThePassword

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package com.example.accessingdatamysql;


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

// Hibernate automatically translates the entity into a table.

@Entity //这个注解告诉Hibernate用这个类生成一个表
		// 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;
  }
}

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package com.example.accessingdatamysql;

import org.springframework.data.repository.CrudRepository;

import com.example.accessingdatamysql.User;

// 这个类会被Spring自动实现为一个叫userRepository的类
// CURD 指 Create, Read, Update, Delete
// This will be AUTO IMPLEMENTED by Spring into a Bean called userRepository
// CRUD refers Create, Read, Update, Delete

public interface UserRepository extends CrudRepository<User, Integer> {
}

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import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller //这个注解指出这个类是一个控制器
@RequestMapping(path="/demo") //这个注解表示这个类接收/demo开头的请求(/demo在Application的路径后)
public class MainController {
  @Autowired  //这个注解指出这里需要获得一个叫userRepository的bean
              //这个bean是刚才被Spring自动生成的，它被用来处理数据
  private UserRepository userRepository;

  @PostMapping(path="/add") //发送POST请求到路径/demo/add时由这个方法处理
  public @ResponseBody String addNewUser (@RequestParam String name
                  , @RequestParam String email) {
    /**
     * @ResponseBody 意思是这个方法返回的 String 内容就是服务器响应的具体内容，
     *  ,而不是视图名称
     * @RequestParam 意思是将该参数和发送到服务器的GET/POST请求的参数 对应 起来
     */

          User n = new User();
          n.setName(name);
          n.setEmail(email);
          userRepository.save(n);
          return "Saved";
  }

  @GetMapping(path="/all")  //发送GET请求到路径/demo/all时由这个方法处理
  public @ResponseBody Iterable<User> getAllUsers() {
    // 返回包含所有用户的JSON或XML
    return userRepository.findAll();
  }
}

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package com.example.accessingdatamysql;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class AccessingDataMysqlApplication {

	public static void main(String[] args) {
		SpringApplication.run(AccessingDataMysqlApplication.class, args);
	}

}