javaWeb客户端使用缓存过滤器服务器端使用gzip压缩提高访问效率

缓存过滤器：让客户端使用已经加载过的资源，不重复到服务器端请求资源。

package org.per.lm.cachefilter;import java.io.IOException;import java.io.PrintStream;import java.util.ArrayList;import java.util.List;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class CacheFilter  implements Filter{  boolean isFil = false;//是否进行过滤  boolean isPrintMsg = false;//是否在控制台显示过滤消息  List<String> noFilFolder = null;  public void init(FilterConfig config) throws ServletException {    if (config.getInitParameter("isFil").toLowerCase().equals("true"))      this.isFil = true;    if (this.isFil) {      if (config.getInitParameter("noFilFolder") != null) {        String noFilFolderstr = config.getInitParameter("noFilFolder");        if (!noFilFolderstr.equals("")) {          if (noFilFolderstr.indexOf(",") == -1) {            this.noFilFolder = new ArrayList();            this.noFilFolder.add(noFilFolderstr);          } else {            this.noFilFolder = new ArrayList();            String[] noFilFolderarr = noFilFolderstr.split(",");            for (String s : noFilFolderarr) {              this.noFilFolder.add(s);            }          }        }      }      if ((config.getInitParameter("printMsg") != null) &&         (config.getInitParameter("printMsg").toLowerCase().equals("true")))        this.isPrintMsg = true;    }  }  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)    throws IOException, ServletException  {    boolean isdoFilter = true;    if (this.isFil) {      HttpServletRequest httpRequest = (HttpServletRequest)request;      HttpSession session = httpRequest.getSession();      List filterFileNameList = new ArrayList();      if (session.getAttribute("org.per.lm.att.filterFileName") != null)        filterFileNameList = (List)session.getAttribute("org.per.lm.att.filterFileName");      else {        session.setAttribute("org.per.lm.att.filterFileName", filterFileNameList);      }      String url = httpRequest.getServletPath();      url = url.substring(1);      String hz = url.substring(url.lastIndexOf(".") + 1);      isPrintMsg("-------------------------------------");      isPrintMsg("过滤文件集合size:" + filterFileNameList.size());      isPrintMsg(url);      if (url.indexOf("/") != -1) {        boolean flag = false;        if (this.noFilFolder != null) {          for (String name : this.noFilFolder) {            if (url.indexOf(name) == 0) {              flag = true;              isPrintMsg(name + "文件夹不过滤!");              break;            }          }        }        if (!flag) {          if (filterFileNameList.contains(url)) {            isPrintMsg("过滤掉:" + url);            ((HttpServletResponse)response).setStatus(304);            isdoFilter = false;          } else {            isPrintMsg("新增过滤:" + url);            filterFileNameList.add(url);            session.setAttribute("org.per.lm.att.filterFileName", filterFileNameList);          }        }      }      else if (filterFileNameList.contains(url)) {        isPrintMsg("过滤掉:" + url);        ((HttpServletResponse)response).setStatus(304);        isdoFilter = false;      } else {        isPrintMsg("新增过滤:" + url);        filterFileNameList.add(url);        session.setAttribute("org.per.lm.att.filterFileName", filterFileNameList);      }    }    if (isdoFilter)      chain.doFilter(request, response);  }  public void destroy()  {  }  private void isPrintMsg(String log)  {    if (this.isPrintMsg)      System.out.println(log);  }}

web.xml配置：<filter>  <filter-name>cache-filter</filter-name>  <filter-class>org.per.lm.cachefilter.CacheFilter</filter-class>  <init-param>            <param-name>isFil</param-name>            <param-value>true</param-value><!-- 是否开启过滤  true开启  false或其他不开启 -->  </init-param>   <init-param>            <param-name>noFilFolder</param-name>            <param-value>images,js/myjs</param-value><!-- 不需要过滤的文件夹 多个文件夹以,隔开 不填将全过滤-->  </init-param>  <init-param>            <param-name>printMsg</param-name>            <param-value></param-value><!-- 是否打印过滤信息  true打印  false或其他不打印 -->  </init-param>     <init-param>            <param-name>sessionPassedTime</param-name>            <param-value>120</param-value><!-- 设置session过期时间(过滤器的有效时间)  单位分钟  格式不对默认为30分钟　不能设置为０　否则会出错 -->  </init-param>   </filter><filter-mapping>  <filter-name>cache-filter</filter-name>  <url-pattern>*.js</url-pattern><!--要过滤的文件类型-->  <url-pattern>*.css</url-pattern></filter-mapping>

gzip：Gzip开启以后会将输出到用户浏览器的数据进行压缩的处理，这样就会减小通过网络传输的数据量，提高浏览的速度。

package org.per.lm.gzipfilter;import java.io.IOException;    import java.util.Enumeration;    import javax.servlet.Filter;    import javax.servlet.FilterChain;    import javax.servlet.FilterConfig;    import javax.servlet.ServletException;    import javax.servlet.ServletRequest;    import javax.servlet.ServletResponse;    import javax.servlet.http.HttpServletRequest;    import javax.servlet.http.HttpServletResponse;    public class GzipFilter implements Filter {          private boolean isGzip = true;     @SuppressWarnings("unchecked")         public void doFilter(ServletRequest request, ServletResponse response,                 FilterChain chain) throws IOException, ServletException {          boolean compress = false;             if (request instanceof HttpServletRequest){                 HttpServletRequest httpRequest = (HttpServletRequest) request;                 Enumeration headers = httpRequest.getHeaders("Accept-Encoding");                 while (headers.hasMoreElements()){                     String value = (String) headers.nextElement();                     if (value.indexOf("gzip") != -1)                        compress = true;                 }             }             if (compress && isGzip){//如果浏览器支持则压缩                 HttpServletResponse httpResponse = (HttpServletResponse) response;                 httpResponse.addHeader("Content-Encoding", "gzip");                 CompressionResponse compressionResponse= new CompressionResponse(httpResponse);                 chain.doFilter(request, compressionResponse);                 compressionResponse.close();             }else//如果浏览器不支持则不压缩                 chain.doFilter(request, response);                      }         public void init(FilterConfig config) throws ServletException {         String isGzipstr = config.getInitParameter("isGzip");     if(isGzipstr == null || isGzipstr.equals("") || !isGzipstr.toLowerCase().equals("true"))     isGzip = false;     }              public void destroy(){         }     }     import java.io.IOException; import java.io.PrintWriter;    import javax.servlet.ServletOutputStream;    import javax.servlet.http.HttpServletResponse;    import javax.servlet.http.HttpServletResponseWrapper;     public class CompressionResponse extends HttpServletResponseWrapper{    protected HttpServletResponse response;        private ServletOutputStream out;        private CompressedStream compressedOut;       private PrintWriter writer;        protected int contentLength;        public CompressionResponse(HttpServletResponse response) throws IOException {           super(response);        this.response = response;           compressedOut = new CompressedStream(response.getOutputStream());      }    public void setContentLength(int len) {         contentLength = len;        }    public ServletOutputStream getOutputStream() throws IOException {           if (null == out) {               if (null != writer) {                 throw new IllegalStateException("getWriter() has already been called on this response.");               }           out = compressedOut;           }       return out;      }    public PrintWriter getWriter() throws IOException {          if (null == writer) {               if (null != out) {                  throw new IllegalStateException("getOutputStream() has already been called on this response.");            }           writer = new PrintWriter(compressedOut);          }       return writer;        }    public void flushBuffer() {           try {               if (writer != null) {               writer.flush();           }else if (out != null) {                 out.flush();               }       }catch (IOException e) {              e.printStackTrace();           }    }    public void reset() {       super.reset();           try {               compressedOut.reset();           }catch (IOException e) {              throw new RuntimeException(e);           }    }    public void resetBuffer() {           super.resetBuffer();           try {               compressedOut.reset();           }catch (IOException e) {              throw new RuntimeException(e);        }    }    public void close() throws IOException {           compressedOut.close();        } } import java.io.IOException;  import java.util.zip.GZIPOutputStream;  import javax.servlet.ServletOutputStream;  public class CompressedStream extends ServletOutputStream {         private ServletOutputStream out;         private GZIPOutputStream    gzip;       /**      * 指定压缩缓冲流      * @param 输出流到压缩      * @throws IOException if an error occurs with the {@link GZIPOutputStream}.      */         public CompressedStream(ServletOutputStream out) throws IOException {             this.out = out;             reset();         }         /** @see ServletOutputStream * */         public void close() throws IOException {             gzip.close();         }         /** @see ServletOutputStream * */         public void flush() throws IOException {            gzip.flush();         }         /** @see ServletOutputStream * */         public void write(byte[] b) throws IOException {             write(b, 0, b.length);         }         /** @see ServletOutputStream * */         public void write(byte[] b, int off, int len) throws IOException {             gzip.write(b, off, len);         }         /** @see ServletOutputStream * */         public void write(int b) throws IOException {             gzip.write(b);         }              public void reset() throws IOException {             gzip = new GZIPOutputStream(out);         }  }  

 web.xml配置： <filter>    <filter-name>gzip</filter-name>    <filter-class>org.per.lm.gzipfilter.GzipFilter</filter-class><!-- 在服务器端进行gzip压缩 -->    <init-param>            <param-name>isGzip</param-name>            <param-value>true</param-value><!-- 是否开启gzip压缩  只有为true开启  false或其他不开启 -->    </init-param>   </filter><filter-mapping>    <filter-name>gzip</filter-name>    <url-pattern>*.js</url-pattern><!--需要压缩的类型-->        <url-pattern>*.css</url-pattern>     <url-pattern>*.html</url-pattern>     <url-pattern>*.htm</url-pattern>    </filter-mapping>

经过测试，这两个过滤器可以结合使用。