前瞻：Spring 6.0 M1发布，将停止支持Freemarker和JSP

/**
 * 6.0之前
 * @author felord.cn
 */
@Component
@RequestMapping("/foo")
public class FooController {

    @GetMapping("/hello")
    public Map<String, String> hello() {
        return Collections.singletonMap("hello", "world");
    }

}

/**
 *  6.0 之前
 *
 * @since 3.0
 */
public enum HttpMethod {

 GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE;

 private static final Map<String, HttpMethod> mappings = new HashMap<>(16);

 static {
  for (HttpMethod httpMethod : values()) {
   mappings.put(httpMethod.name(), httpMethod);
  }
 }

 @Nullable
 public static HttpMethod resolve(@Nullable String method) {
  return (method != null ? mappings.get(method) : null);
 }
    
 public boolean matches(String method) {
  return name().equals(method);
 }

}

public final class HttpMethod implements Comparable<HttpMethod>, Serializable {

 private static final long serialVersionUID = -70133475680645360L;

 private static final HttpMethod[] values;

 private static final Map<String, HttpMethod> mappings = new HashMap<>(16);
 
 public static final HttpMethod GET = new HttpMethod("GET");
 
 public static final HttpMethod HEAD = new HttpMethod("HEAD");
 
 public static final HttpMethod POST = new HttpMethod("POST");
 
 public static final HttpMethod PUT = new HttpMethod("PUT");
   // 其它省略
}