Spring 如何从控制器调用服务

我正在尝试从控制器调用以下服务：

@Service
class MyMailService {

    private final SendGrid sendGrid;

    @Inject
    public SendGridMailService(SendGrid sendGrid) {
        this.sendGrid = sendGrid;
    }

    void sendMail() {
        Request request = new Request();
        Response response = this.sendGrid.api(request);                
    }
}

# controller
public String index(Model model) {
    MyMailService.sendMail() // how to do this properly?
    return "register";
}

和我的控制器：

@Service
class MyMailService {

    private final SendGrid sendGrid;

    @Inject
    public SendGridMailService(SendGrid sendGrid) {
        this.sendGrid = sendGrid;
    }

    void sendMail() {
        Request request = new Request();
        Response response = this.sendGrid.api(request);                
    }
}

# controller
public String index(Model model) {
    MyMailService.sendMail() // how to do this properly?
    return "register";
}

---

从控制器调用此命令的正确方式是什么？基本上，我正在尝试“自动配置”sendgrid，因此每当调用MyMailService类时，我不必使用API键初始化sendgrid对象。

正如其他人所建议的，我也认为您需要花更多时间学习Java和Spring基础知识。但要回答您的问题，您需要在控制器中自动连接/注入

服务
单例对象以使用它：

@Controller
public class ControllerA
{
  .
  .
  .
  @Autowired
  private MyMailService mymailService; //singleton object instance injected to be used/shared by all controllers

public String index(Model model) {
    mymailService.sendMail()
    return "register";
}
  .
  .
  .

}

正如其他人所建议的，我也认为您需要花更多的时间学习Java和Spring基础知识。但要回答您的问题，您需要在控制器中自动连接/注入
服务
单例对象以使用它：

@Controller
public class ControllerA
{
  .
  .
  .
  @Autowired
  private MyMailService mymailService; //singleton object instance injected to be used/shared by all controllers

public String index(Model model) {
    mymailService.sendMail()
    return "register";
}
  .
  .
  .

}

您可以通过以下方式呼叫您的服务

1） 只需将@Autowired添加到类类型

@Autowired
MyMailService myMailService;

2） 使用构造函数注入，如下所示

MyMailService myMailService;    

@Autowired
public WebController(MyMailService myMailService) {
    this.myMailService = myMailService;
}


-  here i assumed my Controller name is WebController

MyMailService myMailService;

@Autowired
public void setMyMailService(MyMailService myMailService) {
    this.myMailService = myMailService;
}

myMailService.sendMail();

3） 使用Setter注入，如下所示

MyMailService myMailService;    

@Autowired
public WebController(MyMailService myMailService) {
    this.myMailService = myMailService;
}


-  here i assumed my Controller name is WebController

MyMailService myMailService;

@Autowired
public void setMyMailService(MyMailService myMailService) {
    this.myMailService = myMailService;
}

myMailService.sendMail();

最后，在控制器中，您可以调用服务类方法，如下所示

MyMailService myMailService;    

@Autowired
public WebController(MyMailService myMailService) {
    this.myMailService = myMailService;
}


-  here i assumed my Controller name is WebController

MyMailService myMailService;

@Autowired
public void setMyMailService(MyMailService myMailService) {
    this.myMailService = myMailService;
}

myMailService.sendMail();

注:
遵循命名约定。
您可以通过以下方式调用您的服务

1） 只需将@Autowired添加到类类型

@Autowired
MyMailService myMailService;

2） 使用构造函数注入，如下所示

MyMailService myMailService;    

@Autowired
public WebController(MyMailService myMailService) {
    this.myMailService = myMailService;
}


-  here i assumed my Controller name is WebController

MyMailService myMailService;

@Autowired
public void setMyMailService(MyMailService myMailService) {
    this.myMailService = myMailService;
}

myMailService.sendMail();

3） 使用Setter注入，如下所示

MyMailService myMailService;    

@Autowired
public WebController(MyMailService myMailService) {
    this.myMailService = myMailService;
}


-  here i assumed my Controller name is WebController

MyMailService myMailService;

@Autowired
public void setMyMailService(MyMailService myMailService) {
    this.myMailService = myMailService;
}

myMailService.sendMail();

最后，在控制器中，您可以调用服务类方法，如下所示

MyMailService myMailService;    

@Autowired
public WebController(MyMailService myMailService) {
    this.myMailService = myMailService;
}


-  here i assumed my Controller name is WebController

MyMailService myMailService;

@Autowired
public void setMyMailService(MyMailService myMailService) {
    this.myMailService = myMailService;
}

myMailService.sendMail();

注:
遵循命名约定。
sendMail（）是一个实例方法，而不是静态方法。所以你需要一个MyMailService的实例来调用它，你可以把它注入到你的控制器中。这是基本的，基本的面向对象的东西。我建议您在深入研究更复杂的内容之前，花更多的时间学习基础知识（什么是方法，什么是静态方法，什么是对象）。sendMail（）是一种实例方法，而不是静态方法。所以你需要一个MyMailService的实例来调用它，你可以把它注入到你的控制器中。这是基本的，基本的面向对象的东西。我建议你花更多的时间学习基础知识（什么是方法，什么是静态方法，什么是对象），然后再深入研究更复杂的东西。