限定符在 spring 中不起作用

Question

CallingApp.java

@Service
@ComponentScan(basePackages = { "com.codegeekslab.type" })
public class CallingApp {

    @Autowired
    @Qualifier("BasicPhone")
    private Phone phone;

    public CallingApp(Phone phone) {
        this.phone = phone;
    }

    public void makeCall(int number) {
        phone.openApp(number);
    }

}

Phone.java

package com.geekslab.device;

public interface Phone {

    public void openApp(int number);

}

基本Phone.java

package com.codegeekslab.type;

import org.springframework.context.annotation.Primary;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

import com.geekslab.device.Phone;
@Component("BasicPhone")
 public class BasicPhone implements Phone {
    {
        System.out.println("BasicPhone");
    }

    public void openApp(int number) {
        System.out.println("calling via simcard... " + number);
    }

}

聪明Phone.java

package com.codegeekslab.type;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

import com.geekslab.device.Phone;

@Component("SmartPhone")
public class SmartPhone implements Phone {
    {
        System.out.println("SmartPhone");
    }

    public void openApp(int number) {
        System.out.println("calling via whatsapp..." + number);
    }

}

Test.java

package com.codegeekslab.test;

 import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.codegeekslab.app.CallingApp;
import com.codegeekslab.type.BasicPhone;
import com.codegeekslab.type.SmartPhone;
import com.geekslab.device.Phone;

 public class Test {

    public static void main(String[] args) {

        //ApplicationContext context =
        //      new GenericXmlApplicationContext("beans.xml");
        //SpringHelloWorld helloSpring  = context.getBean("springHelloWorld", SpringHelloWorld.class);
        //comment this for xml less spring 
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
         context.scan("com.codegeekslab.app","com.codegeekslab.type");
        //context.register( BasicPhone.class,SmartPhone.class,CallingApp.class);
         context.refresh();
        CallingApp  callingApp  = context.getBean("callingApp", CallingApp.class);  
        callingApp.makeCall(99999);

    }
}

即使我在 CallingApp class 中给出限定符 @Qualifier("BasicPhone") ，我得到 Exception 如下：

No qualifying bean of type [com.geekslab.device.Phone] is defined: expected single matching bean but found 2: BasicPhone,SmartPhone

Answer 1

您在 CallingApp 服务中将 phone 作为构造函数参数传递，但未指定 bean。

尝试在您的构造函数中放置一个限定符，或者坚持使用您已经做过的自动装配注入。

Answer 2

我删除了 CallingApp class 构造函数并且它起作用了。

 public CallingApp(Phone phone) {
                this.phone = phone;
            }

因为构造函数正在覆盖 setter 方法。

Answer 3

您需要添加无参数构造函数

public CallingApp(){
    //do nothing
}
public CallingApp(Phone phone) {
    this.phone = phone;
}

限定符在 spring 中不起作用

Qualifier not working in spring

java

spring

qualifiers

autowired