Choose Controller Bean instance by RequestMapping

I want Spring to create 2 instances of FooController. Requests to /foo should be handled by one of the instances and requests to /bar should be handled by the other instance. I want something like the below, but of course @RequestMapping doesn't work that way and also Spring gives me the ambiguous mapping error on FooController as well.

@RestController
public class FooController {
  String name;
  public FooController(String name) { this.name = name; }
}

@Configuration
public class FooControllerConfig {
  @Bean
  @RequestMapping("/foo")
  public FooController getFooFooController(){
    return new FooController("foo");
  }
  @Bean
  @RequestMapping("/bar")
  public FooController getBarFooController(){
    return new FooController("bar");
  }
}

</details>


# 答案1
**得分**: 2

我真的很困惑，为什么您需要这个要求？您能解释一下为什么需要这个要求吗？是每个映射都需要不同的名称吗？

首先，您不应该将Beans映射到RequestMapping上。虽然我甚至不确定Spring应用程序是否会启动，但每次访问这些映射之一时，都可能会创建一个具有相同名称的新Bean，这可能会引发错误。

您可能可以通过自己的注解处理来克服重复的名称，但这比看起来值得的工作要多得多。

仅仅看看您的代码，有没有任何理由不满足您的要求呢？

```java
@RestController
public class FooController {

    private static final fooName = "fooName";
    private static final barName = "barName";

    @RequestMapping("/foo")
    public String getFoo(){
        return fooName;
    }

    @RequestMapping("/bar")
    public String getBar(){
      return barName;
    }
}

@RestController
public class FooController {
private static final fooName = "fooName";
private static final barName = "barName";
@RequestMapping("/foo")
public String getFoo(){
return fooName;
}
@RequestMapping("/bar")
public String getBar(){
return barName;
}
}

答案2

得分: 1

不要在家里尝试这个。这段代码是由一个无聊的专业训练人员执行的...

您可以拥有同一个控制器类的多个实例，每个实例通过控制器中的相同或不同方法处理不同的URL。唯一的问题是，我不知道如何只使用注释来做到这一点。我刚刚所做的方法是在初始化时动态注册每个请求映射。FooController变为原型bean（使用注释定义），因此您可以让Spring多次实例化它，每个映射实例化一次

FooController.java

@Controller
@Scope("prototype")
public class FooController {

    private String name;

    public FooController() {}

    public FooController(String name) {
        this.name = name;
    }

    public ResponseEntity<String> handleRequests() throws Exception {
        return new ResponseEntity<>("Yo: " + name + " " + this.hashCode(), HttpStatus.OK);
    }
}

EndpointService.java

@Service
public class EndpointService {

    @Autowired
    private BeanFactory beanFactory;

    @Autowired
    private RequestMappingHandlerMapping requestMappingHandlerMapping;

    public void addFooController(String urlPath, String name) throws NoSuchMethodException {

        RequestMappingInfo requestMappingInfo = RequestMappingInfo
                .paths(urlPath)
                .methods(RequestMethod.GET)
                .produces(MediaType.APPLICATION_JSON_VALUE)
                .build();

        requestMappingHandlerMapping.registerMapping(requestMappingInfo,
                beanFactory.getBean(FooController.class, name),
                FooController.class.getDeclaredMethod("handleRequests"));
    }

    @EventListener
    public void handleContextRefreshEvent(ContextRefreshedEvent ctxStartEvt) {
        try {
            addFooController("/blah1", "blahblah1");
            addFooController("/blah2", "blahblah2");
            addFooController("/blah3", "blahblah3");
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }
}

结果：

访问 http://localhost:8080/blah1 返回：Yo: blahblah1 1391627345

访问 http://localhost:8080/blah3 返回：Yo: blahblah3 2078995154

@Controller
@Scope("prototype")
public class FooController {
private String name;
public FooController() {}
public FooController(String name) {
this.name = name;
}
public ResponseEntity<String> handleRequests() throws Exception {
return new ResponseEntity<>("Yo: " + name + " " + this.hashCode(), HttpStatus.OK);
}

@Service
public class EndpointService {
@Autowired
private BeanFactory beanFactory;
@Autowired
private RequestMappingHandlerMapping requestMappingHandlerMapping;
public void addFooController(String urlPath, String name) throws NoSuchMethodException {
RequestMappingInfo requestMappingInfo = RequestMappingInfo
.paths(urlPath)
.methods(RequestMethod.GET)
.produces(MediaType.APPLICATION_JSON_VALUE)
.build();
requestMappingHandlerMapping.registerMapping(requestMappingInfo,
beanFactory.getBean(FooController.class, name),
FooController.class.getDeclaredMethod("handleRequests"));
}
@EventListener
public void handleContextRefreshEvent(ContextRefreshedEvent ctxStartEvt) {
try {
addFooController("/blah1", "blahblah1");
addFooController("/blah2", "blahblah2");
addFooController("/blah3", "blahblah3");
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}
}

http://localhost:8080/blah1 returns: Yo: blahblah1 1391627345
http://localhost:8080/blah3 returns: Yo: blahblah3 2078995154