我了解Spring DI的基本原理。
但我不明白的是,在使用
例如,在下面的示例中,方法
但我不明白的是,在使用
@Bean
方法参数注入时,Spring如何知道参数名称以便根据参数名称从其bean工厂中注入bean?例如,在下面的示例中,方法
fernas1
和fernas2
的参数在运行时被擦除。然而,Spring仍然可以将正确的Abbas
bean实例注入其中。@SpringBootApplication
public class DemoApplication {
@Autowired
private Abbas abbas1; // this is understandable, hence the field name is available at runtime
@Autowired
private Abbas abbas2; // this is understandable, hence the field name is available at runtime
public static void main(String[] args) {
ConfigurableApplicationContext ctx = SpringApplication.run(DemoApplication.class, args);
Map<String, Fernas> beansOfType = ctx.getBeansOfType(Fernas.class);
System.out.println(beansOfType);
Arrays.stream(DemoApplication.class.getMethods())
.filter(m -> m.getName().startsWith("fernas"))
.flatMap(m -> Stream.of(m.getParameters()))
.map(Parameter::getName)
.forEach(System.out::println);
System.out.println(ctx.getBean(DemoApplication.class).abbas1);
System.out.println(ctx.getBean(DemoApplication.class).abbas2);
}
class Abbas {
String name;
@Override
public String toString() {
return name;
}
}
class Fernas {
Abbas abbas;
@Override
public String toString() {
return abbas.toString();
}
}
@Bean
public Abbas abbas1() {
Abbas abbas = new Abbas();
abbas.name = "abbas1";
return abbas;
}
@Bean
public Abbas abbas2() {
Abbas abbas = new Abbas();
abbas.name = "abbas2";
return abbas;
}
// this is not understandable, hence the parameter name is NOT available at runtime
@Bean
public Fernas fernas1(Abbas abbas1) {
Fernas fernas1 = new Fernas();
fernas1.abbas = abbas1;
return fernas1;
}
// this is not understandable, hence the parameter name is NOT available at runtime
@Bean
public Fernas fernas2(Abbas abbas2) {
Fernas fernas2 = new Fernas();
fernas2.abbas = abbas2;
return fernas2;
}
}
编辑: @Javier提供的相同的问题和解决方案都适用于 method
和 constructor
参数。