java - Spring组件对一个字段的多个实现的依赖注入(inject)

Question

我有一个 MyMessageConsumer 类，它是一个 spring 组件。我有 Autowiring 的 MessageReceiver 接口(interface)，如下所示:

    @Component
    @Scope("prototype")
    public class MyMessageConsumer {

     @Autowired
     private MessageReceiver messageReceiver;

    }

我想创建 MyMessageConsumer 的多个 bean 实例，每个实例都有不同的 MessageReceiver 实现，例如 TextMessageReceiver、XMLMessageReceiver、JSONMessageReceiver。

    // If a setter is provided in MyMessageConsumer, then it would be suffiecent. But how to do it without setter.

在上述场景中是否可以在没有 setter 方法的情况下注入(inject)不同的实现？否则请建议最佳替代方案。

提前致谢。

Answer 1

一个选项是删除 MyMessageConsumer 中的 @autowired。

@Component
@Scope("prototype")
public class MyMessageConsumer {

    private MessageReceiver messageReceiver;

    public MessageReceiver getMessageReceiver() {
        return messageReceiver;
    }

    public void setMessageReceiver(MessageReceiver messageReceiver) {
        this.messageReceiver = messageReceiver;
    }
}

然后定义 MessageReceiver bean

@Bean
public TextMessageReceiver textMessageReceiver() {
    return new TextMessageReceiver();
}

@Bean
public XMLMessageReceiver xMLMessageReceiver() {
    return new XMLMessageReceiver();
}

然后您需要定义您的 MessageConsumers

@Bean
@Autowired
public MyMessageConsumer myMessageConsumer1(TextMessageReceiver textMessageReceiver) {
    MyMessageConsumer m = new MyMessageConsumer();
    m.setMessageReceiver(textMessageReceiver);
    return m;
}

@Bean
@Autowired
public MyMessageConsumer myMessageConsumer2(XMLMessageReceiver xMLMessageReceiver) {
    MyMessageConsumer m = new MyMessageConsumer();
    m.setMessageReceiver(xMLMessageReceiver);
    return m;
}