org.apache.juneau.rest.matcher.RestMatcher Maven / Gradle / Ivy

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package org.apache.juneau.rest.matcher;

import jakarta.servlet.http.*;

import org.apache.juneau.rest.annotation.*;

/**
 * Class used for defining method-level matchers using the {@link RestOp#matchers() @RestOp(matchers)} annotation.
 *
 * 
 * Matchers are used to allow multiple Java methods to handle requests assigned to the same URL path pattern, but
 * differing based on some request attribute, such as a specific header value.
 * For example, matchers can be used to provide two different methods for handling requests from two different client
 * versions.
 *
 * 

 * Java methods with matchers associated with them are always attempted before Java methods without matchers.
 * This allows a 'default' method to be defined to handle requests where no matchers match.
 *
 * 

 * When multiple matchers are specified on a method, only one matcher is required to match.
 * This is opposite from the {@link RestOp#guards() @RestOp(guards)} annotation, where all guards are required to match in order to
 * execute the method.
 *
 * 
Example:
 * 
 * 	public class MyResource extends BasicRestServlet {
 *
 * 		@RestGet(path="/foo", matchers=IsDNT.class)
 * 		public Object doGetWithDNT() {
 * 			// Handle request with Do-Not-Track specified
 * 		}
 *
 * 		@RestGet("/foo")
 * 		public Object doGetWithoutDNT() {
 * 			// Handle request without Do-Not-Track specified
 * 		}
 * 	}
 *
 * 	public class IsDNT extends RestMatcher {
 * 		@Override
 * 		public boolean matches(HttpServletRequest req) {
 * 			return "1".equals(req.getHeader("DNT"));
 * 		}
 * 	}
 * 
 *
 * 
 * Instances must provide one of the following public constructors:
 * 

 * 	No-args.
 * 	
The following args: Object resource, Method javaMethod.
 * 		
This gives access to the servlet/resource and Java method it's applied to.
 * 
 *
 * See Also:

 * 	@RestOp-Annotated Methods
 * 
 */
public abstract class RestMatcher {

	/**
	 * Returns true if the specified request matches this matcher.
	 *
	 * @param req The servlet request.
	 * @return true if the specified request matches this matcher.
	 */
	public abstract boolean matches(HttpServletRequest req);

	/**
	 * Returns true if this matcher is required to match in order for the method to be invoked.
	 *
	 * 
	 * If false, then only one of the matchers must match.
	 *
	 * @return true if this matcher is required to match in order for the method to be invoked.
	 */
	public boolean required() {
		return false;
	}
}