Java 之Filter 应用实例--UrlWriterFilter 仿urlrewrite 用来支持二级域名重写

一、背景

之前的文章介绍了用Java 做301重定向，即使用Url Rewrite 进行URL 重写来实现网站的伪静态。现在产品这边又多了一个需求，需要网站支持二级域名跳转，比如访问abc.baidu.com 能够跳转到 www.baidu.com/abc。这个功能其实和301 重定向原理是一样的，只不过我们需要自己自定义一个重定向规则。

二、代码实现

UrlWriterFactory 工厂类

public class UrlWriterFactory {
	private static Log logger = LogFactory.getLog(UrlWriterFactory.class);

	private static final String FORWARD = "forward";

	private static final String REDIRECT = "redirect";

	private static final String DEFAULT_CONFIG_FILE_NAME = "config/urlrewrite.xml";

	private static String urlWriterConfigName;

	/**
	 * 版本号
	 */
	private Long version = System.currentTimeMillis();

	private static List<UrlWriter> urlPatternList = new ArrayList<UrlWriter>();

	public void init() {
		if (StringUtils.isBlank(urlWriterConfigName)) {
			urlWriterConfigName = DEFAULT_CONFIG_FILE_NAME;
		}
		InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(urlWriterConfigName);
		if (null == inputStream) {
			throw new RuntimeException("没有配置urlrewrite.xml");
		}
		urlPatternList = initUrlWriter(inputStream);
	}
@SuppressWarnings("unchecked")
	private List<UrlWriter> initUrlWriter(InputStream inputStream) {
		List<UrlWriter> urlPatternList = new ArrayList<UrlWriter>();
		SAXReader reader = new SAXReader();
		try {
			Document doc = reader.read(inputStream);
			List<Node> nodes = doc.selectNodes("urlrewrite/rule");

			for (Node elm : nodes) {
				UrlWriter urlMapping = new UrlWriter();
				String from = ((Element) elm).elementText("from");
				from = StringUtils.isBlank(from) ? "" : from;
				urlMapping.setFrom(from);

				String to = ((Element) elm).elementText("to");
				to = StringUtils.isBlank(to) ? "" : to;
				urlMapping.setTo(to);

				Attribute attribute = ((Element) elm).element("to").attribute("type");
				String type = FORWARD;
				if (null != attribute) {
					if (StringUtils.isBlank(attribute.getValue())) {
						type = attribute.getValue();
					}
				}
				urlMapping.setType(type);
				urlPatternList.add(urlMapping);
			}
			return urlPatternList;
		} catch (DocumentException e) {

			logger.error("解析url.xml时发现异常:" + e);
		}
		return urlPatternList;

	}

public static UrlResult getUrlResult(String url) {
		if (StringUtils.isEmpty(url)) {
			return null;
		}
		url = filterUrlStyle(url);
		UrlResult urlResult = new UrlResult(false, "");
		for (UrlWriter urlMapping : urlPatternList) {
			Pattern pattern = Pattern.compile(urlMapping.getFrom());
			Matcher matcher = pattern.matcher(url);
			if (matcher.find()) {
				// urlResult.setUrl(matcher.replaceAll(urlMapping.getTo()));
				String urlTo = urlMapping.getTo();
				for (int i = 1; i <= matcher.groupCount(); i++) {
					urlTo = urlTo.replace("$" + i, matcher.group(i));
				}
				if (!urlTo.contains(".html")) {
					urlTo = urlTo + File.separator + "index.html";
				}
				urlResult.setUrl(urlTo);
				if (urlMapping.getType().equals(REDIRECT)) {
					urlResult.setFlag(true);
				}
				return urlResult;
			}
		}
		return urlResult;
	}

public static class UrlResult {
		private boolean flag = false;
		private String url = "";

		public UrlResult(boolean flag, String url) {
			super();
			this.flag = flag;
			this.url = url;
		}

		public boolean isFlag() {
			return flag;
		}

		public void setFlag(boolean flag) {
			this.flag = flag;
		}

		public String getUrl() {
			return url;
		}

		public void setUrl(String url) {
			this.url = url;
		}
	}

public String getUrlWriterConfigName() {
		return urlWriterConfigName;
	}

	public void setUrlWriterConfigName(String urlWriterConfigName) {
		UrlWriterFactory.urlWriterConfigName = urlWriterConfigName;
	}

	public Long getVersion() {
		return version;
	}

	public void setVersion(Long version) {
		this.version = version;
	}

	private static String filterUrlStyle(String url) {
		if (url.indexOf("://") != -1) {
			url = url.substring(url.indexOf("://") + 3);
		}
		// if (url.length() > 1 && url.endsWith("/")) {
		// url = url.substring(0, url.length() - 1);
		// }
		return url;
	}

public static boolean checkIfSecondDomain(String url) {
		if (StringUtil.isBlank(url)) {
			return false;
		}
		if (!url.contains("\.company")) {
			return false;
		}
		return false;
	}

UrlWriter 实体bean

public class UrlWriter {
	private String from;
	private String to;
	private String type;

	public String getFrom() {
		return from;
	}

	public void setFrom(String from) {
		this.from = from;
	}

	public String getTo() {
		return to;
	}

	public void setTo(String to) {
		this.to = to;
	}

	public String getType() {
		return type;
	}

	public void setType(String type) {
		this.type = type;
	}
}

UrlWriterFilter 过滤器方法

public class UrlWriterFilter implements Filter {

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpServletRequest httpServletRequest = (HttpServletRequest) request;
		HttpServletResponse httpServletResponse = (HttpServletResponse) response;
		String requestURL = httpServletRequest.getRequestURL().toString();
		System.out.println("URL的值" + requestURL);
		// 屏蔽镜像网站
		if (requestURL.indexOf(".xiniu1688.com") == -1) {
			request.getRequestDispatcher("/error/404.do").forward(request, response);// 跳转到信息提示页面！！
			return;
		}
		// 非二级域名直接过滤掉
		if (requestURL.startsWith("http://www.xxxx.com") || requestURL.startsWith("http://xxxx.com")) {
			chain.doFilter(request, response);
			return;
		}
		UrlWriterFactory uf = new UrlWriterFactory();
		uf.init();
		UrlResult urlResult = UrlWriterFactory.getUrlResult(requestURL);

		if (null != urlResult && !StringUtil.isBlank(urlResult.getUrl())) {
			String realPath = urlResult.getUrl();
			if (urlResult.isFlag()) {
				httpServletResponse.sendRedirect(realPath);
				return;
			} else {
				if (!realPath.startsWith("/")) {
					realPath = "/" + realPath;
				}
				httpServletRequest.getRequestDispatcher(realPath).forward(request, response);
				return;
			}
		} else {
			chain.doFilter(request, response);
		}
	}

	@Override
	public void destroy() {
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
	 */
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {

	}

}

urlrewrite.xml 配置文件，放在根目录下面的conf 文件夹下

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE urlrewrite PUBLIC "-//tuckey.org//DTD UrlRewrite 4.0//EN"
        "http://www.tuckey.org/res/dtds/urlrewrite4.0.dtd">
<urlrewrite>
	<rule>
		<from>^(.*).xxxx.com/(.*)$</from>
		<to>/company/$1/$2</to>
	</rule>
</urlrewrite>

web.xml 配置

<!-- urlrewriter 重写 -->
	<filter>
        <filter-name>SecDomainUrlWriterFilter</filter-name>
        <filter-class>com.xxx.xxx.urlwriter.UrlWriterFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>SecDomainUrlWriterFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

 参考: 仿一个urlrewrite 支持二级域名

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