SPRING与设计模式--单件模式

SPRING与设计模式--单件模式

单体模式是一种常用的模式，顾名思义就是一个类只允许有一个实例。springsecurity大都使用饿汉模式，在类加载时就创建好了实例。其他模式见：https://www.jianshu.com/p/c7ca51d2816e

 AnyRequestMatcher源码：

package org.springframework.security.web.util.matcher;

import java.util.Arrays;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.util.Assert;

/**
 * {@link RequestMatcher} that will return true if all of the passed in
 * {@link RequestMatcher} instances match.
 *
 * @author Rob Winch
 * @since 3.2
 */
public final class AndRequestMatcher implements RequestMatcher {
	private final Log logger = LogFactory.getLog(getClass());

	private final List<RequestMatcher> requestMatchers;

	/**
	 * Creates a new instance
	 *
	 * @param requestMatchers the {@link RequestMatcher} instances to try
	 */
	public AndRequestMatcher(List<RequestMatcher> requestMatchers) {
		Assert.notEmpty(requestMatchers, "requestMatchers must contain a value");
		if (requestMatchers.contains(null)) {
			throw new IllegalArgumentException(
					"requestMatchers cannot contain null values");
		}
		this.requestMatchers = requestMatchers;
	}

	/**
	 * Creates a new instance
	 *
	 * @param requestMatchers the {@link RequestMatcher} instances to try
	 */
	public AndRequestMatcher(RequestMatcher... requestMatchers) {
		this(Arrays.asList(requestMatchers));
	}

	public boolean matches(HttpServletRequest request) {
		for (RequestMatcher matcher : requestMatchers) {
			if (logger.isDebugEnabled()) {
				logger.debug("Trying to match using " + matcher);
			}
			if (!matcher.matches(request)) {
				logger.debug("Did not match");
				return false;
			}
		}
		logger.debug("All requestMatchers returned true");
		return true;
	}

	@Override
	public String toString() {
		return "AndRequestMatcher [requestMatchers=" + requestMatchers + "]";
	}
}