java - Spring 中抽象类的构造函数依赖注入(inject)

Question

我想在我的应用程序中使用构造函数依赖注入(inject)。

我创建了这个 Controller :

public abstract class BonanzaCloudController {


    protected final UserService userService;

    protected BonanzaCloudController(UserService userService) {
        this.userService = userService;
    }

...
}

还有这个

@Controller
public class AppErrorController extends BonanzaCloudController implements ErrorController {

    private final ErrorAttributes errorAttributes;    

    private final EmailService emailService;

    public AppErrorController(ErrorAttributes errorAttributes, EmailService emailService) {
        this.errorAttributes = errorAttributes;
        this.emailService = emailService;
    }
...
}

但是我有这个编译错误:

There is no default constructor available in BonanzaCloudController

Answer 1

AppErrorController 是 BonanzaCloudController 的子类，因此 AppErrorController 的构造函数必须调用 BonanzaCloudController 的构造函数(按照java定义的规则)。

因此 AppErrorController 的构造函数必须是

public AppErrorController(UserService userService, ErrorAttributes errorAttributes, EmailService emailService) {
    super(userService);
    this.errorAttributes = errorAttributes;
    this.emailService = emailService;
}

虽然 userService 不必是第一个参数，但只有 super() 调用必须是第一个。