功能强大的 Servlet Filter 完整源代码-JAVA91知识库

功能强大的 Servlet Filter 完整源代码

转自:http://dev.21tx.com

/*
 * <p>Company: </p>
 * @author liubaojun
 * @version 1.0
 * Created on 2004-11-29
 * 来源于 elinkBSP 部分源代码
 */
package com.elink.control;
import Java.io. * ;
import java.util. * ;
import java.util.zip. * ;
import javax.Servlet. * ;
import javax.servlet.http. * ;
//import com.elink.util.*;
/**
 * @author liubj
 */
public class BusiFilter implements Filter {
    private FilterConfig config = null;
    private HashMap expiresMap = null;
    private String encoding = null;
    public void init(FilterConfig filterConfig) {
        this.config = filterConfig;
        this.encoding = config.getInitParameter("encoding");
        if (encoding == null || encoding.length() == 0) {
            encoding = "GBK";
        }
        expiresMap = new HashMap();
        Enumeration names = config.getInitParameterNames();
        while (names.hasMoreElements()) {
            String paramName = (String) names.nextElement();
            if (!"encoding".equals(paramName)) {
                String paramValue = config.getInitParameter(paramName);
                try {
                    Integer expires = Integer.valueOf(config.getInitParameter(paramName));
                    expiresMap.put(paramName, expires);
                } catch(Exception ex) {
                    //LogUtil.logError( "Filter."+paramValue+"="+paramValue);
                }
            }
        }
    }

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
    ServletException {
        // 汉字问题
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        httpRequest.setCharacterEncoding(encoding);
        //  chain.doFilter(request, response);

// 压缩传输
        HttpServletResponse httpResponse = (HttpServletResponse) response;
        String uri = httpRequest.getRequestURI();

String transferEncoding = getGZIPEncoding((HttpServletRequest) request);
        if (transferEncoding == null) {
            setResponseHeader(httpResponse, uri, transferEncoding);
            chain.doFilter(request, response);
        } else {
            if (uri.endsWith(".ctl") || uri.endsWith("busictrl")) // 不处理的 URL
            {
                chain.doFilter(request, response);
            } else {
                setResponseHeader(httpResponse, uri, transferEncoding);
                httpResponse.setHeader("Content-Encoding", transferEncoding);
                GZIPEncodableResponse wrappedResponse = new GZIPEncodableResponse((HttpServletResponse) response);
                chain.doFilter(request, wrappedResponse);
                wrappedResponse.flush();
            }
        }
    }
    public void destroy() {}
    private void setResponseHeader(HttpServletResponse response, String uri, String transferEncoding) {
        //LogUtil.logDebug( uri + ".Accept-Encoding: "+ transferEncoding);
        String ext = null;
        int dot = uri.lastIndexOf(".");
        if (dot != -1) {
            ext = uri.substring(dot + 1);
        }
        if (ext != null && ext.length() > 0) {
            Integer expires = (Integer) expiresMap.get(ext);
            if (expires != null) {
                //LogUtil.logDebug( uri + ".Expires: "+ expires.intValue());
                if (expires.intValue() > 0) {
                    response.setHeader("Cache-Control", "max-age=" + expires.intValue()); //HTTP 1.1
                } else {
                    response.setHeader("Cache-Control", "no-cache");
                    response.setHeader("Pragma", "no-cache"); //HTTP 1.0
                    response.setDateHeader("Expires", expires.intValue());
                }
            }
        }
    }

private static String getGZIPEncoding(HttpServletRequest request) {
        String acceptEncoding = request.getHeader("Accept-Encoding");
        if (acceptEncoding == null) return null;
        acceptEncoding = acceptEncoding.toLowerCase();
        if (acceptEncoding.indexOf("x-gzip") >= 0) {
            return "x-gzip";
        }
        if (acceptEncoding.indexOf("gzip") >= 0) {
            return "gzip";
        }
        return null;
    }

private class GZIPEncodableResponse extends HttpServletResponseWrapper {
        private GZIPServletStream wrappedOut;

public GZIPEncodableResponse(HttpServletResponse response) throws IOException {
            super(response);
            wrappedOut = new GZIPServletStream(response.getOutputStream());
        }

public ServletOutputStream getOutputStream() throws IOException {
            return wrappedOut;
        }

private PrintWriter wrappedWriter;

public PrintWriter getWriter() throws IOException {
            if (wrappedWriter == null) {
                wrappedWriter = new PrintWriter(new OutputStreamWriter(getOutputStream(), getCharacterEncoding()));
            }
            return wrappedWriter;
        }

public void flush() throws IOException {
            if (wrappedWriter != null) {
                wrappedWriter.flush();
            }
            wrappedOut.finish();
        }
    }

private class GZIPServletStream extends ServletOutputStream {
        private GZIPOutputStream outputStream;

public GZIPServletStream(OutputStream source) throws IOException {
            outputStream = new GZIPOutputStream(source);
        }

public void finish() throws IOException {
            outputStream.finish();
        }

public void write(byte[] buf) throws IOException {
            outputStream.write(buf);
        }

public void write(byte[] buf, int off, int len) throws IOException {
            outputStream.write(buf, off, len);
        }

public void write(int c) throws IOException {
            outputStream.write(c);
        }

public void flush() throws IOException {
            outputStream.flush();
        }

public void close() throws IOException {
            outputStream.close();
        }
    }
}

配置文件