Question

我试图将FortuneService接口注入到TennisCoach类，但是遇到错误，如果尝试使用new关键字注入它，那么它工作正常。我通过创建HappyFortuneService对象尝试了它。我在TennisCoach课程中尝试过如下 FortuneService fortuneService =新的HappyFortuneService（）;但是，如果我尝试使用构造函数注入来注入它，则会给我以下错误。

我在线程“ restartedMain” java.lang.reflect.InvocationTargetException中遇到诸如Exception之类的错误

package com.annotation;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.annotation.coach.Coach;
import com.annotation.coach.FortuneService;
import com.annotation.coach.HappyFortuneService;
import com.annotation.coach.TennisCoach;

@SpringBootApplication
public class Luv2CodeAnnotationApplication {

    private static final Logger logger = LoggerFactory.getLogger(Luv2CodeAnnotationApplication.class);

    public static void main(String[] args) {
        SpringApplication.run(Luv2CodeAnnotationApplication.class, args);

        Coach coach = new TennisCoach();
        logger.info(coach.getDailyWorkout());
        logger.info(coach.getDailyFortune());

    }

}




package com.annotation.coach;

public interface Coach {

    public String getDailyWorkout();
    public String getDailyFortune();
}




    package com.annotation.coach;

    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.stereotype.Component;

    import com.annotation.Luv2CodeAnnotationApplication;

    @Component
    public class TennisCoach implements Coach {

        private static final Logger logger = LoggerFactory.getLogger(Luv2CodeAnnotationApplication.class);

        private FortuneService fortuneService;

        public TennisCoach(FortuneService fortuneService) {
            this.fortuneService = fortuneService;
        }
        public TennisCoach() {
        }

        @Override
        public String getDailyWorkout() {
            return "*************Tennis Coach Daily Workout*************";
        }

        @Override
        public String getDailyFortune() {
            logger.info("*********INVOKED***************");
            return fortuneService.getFortune();
        }

    }




    package com.annotation.coach;

    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.stereotype.Component;

    @Component
    public class HappyFortuneService implements FortuneService {

        @Override
        public String getFortune() {
            return "*************Happy Fortune Service*************";
        }

    }



package com.annotation.coach;

public interface FortuneService {

    public String getFortune();
}

Answer 1

如果使用new关键字创建任何bean且该bean不会添加到Spring Application Context中，则Coach coach = new TennisCoach（）;没有添加到应用程序上下文中。因此，TennisCoach类无法识别Autowired FortuneService。

您可以使用构造函数进行自动装配，当创建Luv2CodeAnnotationApplication时，会将Coach实例作为构造函数的参数注入。

请在下面找到修改后的代码

@SpringBootApplication

公共类Luv2CodeAnnotationApplication {

private static Coach coach;
private static final Logger logger = LoggerFactory.getLogger(Luv2CodeAnnotationApplication.class);

@Autowired
public Luv2CodeAnnotationApplication(Coach coach) {
    Luv2CodeAnnotationApplication.coach = coach;
}

public static void main(String[] args) {
    SpringApplication.run(Luv2CodeAnnotationApplication.class, args);

  //Coach coach = new TennisCoach();
    logger.info(coach.getDailyWorkout());
    logger.info(coach.getDailyFortune());

}

}

线程“ restartedMain”中的异常java.lang.reflect.InvocationTargetException

1 个答案: