java-redis缓存jsp页面

上代码--原理是在response返回html的时候直接缓存html内容到redis中去

import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import java.io.CharArrayWriter;
import java.io.PrintWriter;

public class ResponseWrapper extends HttpServletResponseWrapper {
    private PrintWriter cachedWriter;
    private CharArrayWriter bufferedWriter;
 
    public ResponseWrapper(HttpServletResponse response) {
        super(response);
        // 这个是我们保存返回结果的地方
        bufferedWriter = new CharArrayWriter();
        // 这个是包装PrintWriter的，让所有结果通过这个PrintWriter写入到bufferedWriter中
        cachedWriter = new PrintWriter(bufferedWriter);
    }
 
    @Override
    public PrintWriter getWriter() {
        return cachedWriter;
    }
 
    /**
     * 获取原始的HTML页面内容。
     *
     * @return
     */
    public String getResult() {
        return bufferedWriter.toString();
    }
}

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.data.redis.core.StringRedisTemplate;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.concurrent.TimeUnit;

public class RedisPageCacheFilter implements Filter {
    private static final Logger log = LoggerFactory.getLogger(RedisPageCacheFilter.class);
 
    private static ApplicationContext ctx;
    private final static String FILTER_URL_PATTERNS = "patterns";
    private static String[] cacheURLs;
    private static int timeOut;

    @Override
    public void init(FilterConfig config) throws ServletException {
        String patterns = config.getInitParameter(FILTER_URL_PATTERNS);
        timeOut= Integer.parseInt(config.getInitParameter("expireTime"));
        cacheURLs = StringUtils.split(patterns, ",");
    }
 
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse resp = (HttpServletResponse) servletResponse;
        HttpServletRequest request = (HttpServletRequest) servletRequest;

        String url = request.getRequestURI();
        boolean flag = false;
        if (cacheURLs != null && cacheURLs.length > 0) {
            for (String cacheURL : cacheURLs) {
                if (url.contains(cacheURL.trim())||url.matches(cacheURL)) {
                    flag = true;
                    break;
                }
            }
        }

        // 如果包含我们要缓存的url 就缓存该页面，否则执行正常的页面转向
        if (flag) {
            String query = request.getQueryString();
            if (query != null) {
                query = "?" + query;
            }

            final String key="REDISCACHE:"+url+query;
            log.info("当前请求缓存为:" + url + query);

            // 访问的是主页
            // 从缓存中得到主页html
            String html = getHtmlFromCache(key);
            if (null == html) {
                // 缓存中没有
                // 截取生成的html并放入缓存
                log.info("缓存不存在，生成缓存");
                ResponseWrapper wrapper = new ResponseWrapper(resp);
                // ***** 以上代码在请求被处理之前执行 *****
                filterChain.doFilter(servletRequest, wrapper);
                // ***** 以下代码在请求被处理后前执行 *****
                // 放入缓存
                html = wrapper.getResult();
                putIntoCache(key,html);
            }

            // 返回响应
            resp.setContentType("text/html; charset=utf-8");
            resp.getWriter().print(html);
        } else {
            filterChain.doFilter(servletRequest, resp);
            return;
        }
    }

    @Override
    public void destroy() {

    }

    private String getHtmlFromCache(String redisKey) {
        return RedisUtil.get(redisKey);
    }
 
    private void putIntoCache(String redisKey,String html) {
        RedisUtil.set(redisKey, html,timeOut*60);
    }
}

 使用方式:配置web.xml

    <!-- 页面缓存配置 redis cache-->
    <filter>
        <filter-name>redisCachingFilter</filter-name>
        <filter-class>xxxxx.xxxxx.xxxx.RedisPageCacheFilter</filter-class>
        <init-param>
            <param-name>suppressStackTrace</param-name>
            <param-value>false</param-value>
        </init-param>
        <init-param>
            <param-name>expireTime</param-name>
            <param-value>1</param-value>
        </init-param>
        <init-param>
            <param-name>patterns</param-name>
            <param-value>/d+.do,/wap/product/list/d+.jhtm,/wap/product/content/d+.action</param-value>
        </init-param>
    </filter>

    <filter-mapping>
        <filter-name>redisCachingFilter</filter-name>
        <url-pattern>*.do</url-pattern>
    </filter-mapping>

    <filter-mapping>
        <filter-name>redisCachingFilter</filter-name>
        <url-pattern>*.action</url-pattern>
    </filter-mapping>