本章目的：使用spring data jpa連線mysql，實現增刪改查和事物的配置。

• pom.xml引入jar

<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>

• application.properties配置資料來源

server.port=20001
spring.datasource.url=jdbc:mysql://localhost:3307/crawler
spring.datasource.username=root
spring.datasource
 
.password=
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.jpa.properties.hibernate.hbm2ddl.auto=update

• 建立實體類User

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

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public
 
 Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    @Column(nullable = false)
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Column(nullable = false)
    public Integer getAge() {
        return age;
    }

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

}

• 建立UserRepository

public interface UserRepository extends JpaRepository<User, Long> {
    User findByName(String name);

    User findByAgeGreaterThan(Integer age);

    List<User> findByNameLike(String name);

}

• 建立UserService

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public User findUser(String name) {
        return userRepository.findByName(name);
    }

    public List<User> findList() {
        return userRepository.findAll();
    }

    public Long save(User user) {
        return userRepository.save(user).getId();
    }

    public void saveListUser(List<User> list) {
        for (User user : list)
            save(user);
    }

}

• 建立API

@RestController
@RequestMapping("/user")
public class UserWeb {
    @Autowired
    private UserService userService;

    @RequestMapping("/find")
    public String findUser(String name) throws Exception {
        return userService.findUser(name).getName();
    }

    @RequestMapping("list")
    public String list() throws JSONException {
        JSONObject out = new JSONObject();
        out.put("list", userService.findList());
        return out.toString();
    }

    @RequestMapping("/save")
    public String save(String name, Integer age) {
        User user = new User();
        user.setName(name);
        user.setAge(age);
        Long id = userService.save(user);
        return id.toString();
    }

    @RequestMapping("/saveList")
    public String saveList(String name, Integer age) {
        List<User> list = new ArrayList<User>();
        for (int i = 6; i < 11; i++) {
            User user = new User();
            user.setName(name + "_0000" + i);
            user.setAge(age);
            list.add(user);
        }
        userService.saveListUser(list);
        return "OK";
    }
}

• 事物
  springboot中的事物非常簡單，只需要兩步

• 主程式中加入註解@EnableTransactionManagement

• service方法中加入註解@Transactional