servlet高级应用过滤器、防盗链等一系列技术工具打包

package cn.jsp.servlet.filter; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.Reader; import java.io.Writer; import java.net.URLEncoder; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class CacheFilter implements Filter { private ServletContext servletContext; // 缓存文件夹，使用Tomcat工作目录 private File temporalDir; // 缓存时间，配置在Filter初始化参数中 private long cacheTime = Long.MAX_VALUE; public void init(FilterConfig config) throws ServletException { temporalDir = (File) config.getServletContext().getAttribute( "javax.servlet.context.tempdir"); servletContext = config.getServletContext(); cacheTime = new Long(config.getInitParameter("cacheTime")); } public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; // 如果为 POST, 则不经过缓存 if ("POST".equals(request.getMethod())) { chain.doFilter(request, response); return; } // 请求的 URI String uri = request.getRequestURI(); if (uri == null) uri = ""; uri = uri.replace(request.getContextPath() + "/", ""); uri = uri.trim().length() == 0 ? "index.jsp" : uri; uri = request.getQueryString() == null ? uri : (uri + "?" + request .getQueryString()); // 对应的缓存文件 File cacheFile = new File(temporalDir, URLEncoder.encode(uri, "UTF-8")); System.out.println(cacheFile); // 如果缓存文件不存在 或者已经超出缓存时间 则请求 Servlet if (!cacheFile.exists() || cacheFile.length() == 0 || cacheFile.lastModified() < System.currentTimeMillis() - cacheTime) { CacheResponseWrapper cacheResponse = new CacheResponseWrapper(response); chain.doFilter(request, cacheResponse); // 将内容写入缓存文件 char[] content = cacheResponse.getCacheWriter().toCharArray(); temporalDir.mkdirs(); cacheFile.createNewFile(); Writer writer = new OutputStreamWriter(new FileOutputStream( cacheFile), "UTF-8"); writer.write(content); writer.close(); } // 请求的ContentType String mimeType = servletContext.getMimeType(request.getRequestURI()); response.setContentType(mimeType); // 读取缓存文件的内容，写入客户端浏览器 Reader ins = new InputStreamReader(new FileInputStream(cacheFile), "UTF-8"); StringBuffer buffer = new StringBuffer(); char[] cbuf = new char[1024]; int len; while ((len = ins.read(cbuf)) > -1) { buffer.append(cbuf, 0, len); } ins.close(); // 输出到客户端 response.getWriter().write(buffer.toString()); } public void destroy() { } }