调用App.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);
}
}
电话.java
package com.geekslab.device;
public interface Phone {
public void openApp(int number);
}
BasicPhone.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);
}
}
智能手机.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);
}
}
测试.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
类中将限定符作为 @Qualifier("BasicPhone")
提供,我也会收到如下异常:
No qualifying bean of type [com.geekslab.device.Phone] is defined: expected single matching bean but found 2: BasicPhone,SmartPhone
最佳答案
您在 CallingApp 服务中将电话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 Autowiring 注入(inject)。
关于java - 限定符在 Spring 不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42245597/