javaee7-samples 是一个项目用来演示 Java EE 7 各种新特性的示例，有超过 160 个示例程序

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However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package org.javaee7.servlet.filters; import java.io.IOException; import java.io.PrintStream; import java.io.PrintWriter; import java.io.StringWriter; 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.annotation.WebFilter; /** * @author Arun Gupta */ @WebFilter(filterName = "LoggingFilter", urlPatterns = {"/*"}) public class LoggingFilter implements Filter { private static final boolean debug = true; // The filter configuration object we are associated with. If // this value is null, this filter instance is not currently // configured. private FilterConfig filterConfig = null; public LoggingFilter() { } private void doBeforeProcessing(ServletRequest request, ServletResponse response) throws IOException, ServletException { if (debug) { log("LoggingFilter:DoBeforeProcessing"); } // Write code here to process the request and/or response before // the rest of the filter chain is invoked. // For example, a logging filter might log items on the request object, // such as the parameters. for (Enumeration en = request.getParameterNames(); en.hasMoreElements();) { String name = (String) en.nextElement(); String values[] = request.getParameterValues(name); int n = values.length; StringBuilder buf = new StringBuilder(); buf.append(name); buf.append("="); for (int i = 0; i < n; i++) { buf.append(values[i]); if (i < n - 1) { buf.append(","); } } log(buf.toString()); } } private void doAfterProcessing(ServletRequest request, ServletResponse response) throws IOException, ServletException { if (debug) { log("LoggingFilter:DoAfterProcessing"); } // Write code here to process the request and/or response after // the rest of the filter chain is invoked. // For example, a logging filter might log the attributes on the // request object after the request has been processed. for (Enumeration en = request.getAttributeNames(); en.hasMoreElements();) { String name = (String) en.nextElement(); Object value = request.getAttribute(name); log("attribute: " + name + "=" + value.toString()); } // For example, a filter might append something to the response. PrintWriter respOut = new PrintWriter(response.getWriter()); respOut.println("<P><B>This has been appended by an intrusive filter.</B>"); } /** * * @param request The servlet request we are processing * @param response The servlet response we are creating * @param chain The filter chain we are processing * * @exception IOException if an input/output error occurs * @exception ServletException if a servlet error occurs */ @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { if (debug) { log("LoggingFilter:doFilter()"); } doBeforeProcessing(request, response); Throwable problem = null; try { chain.doFilter(request, response); } catch (IOException | ServletException t) { // If an exception is thrown somewhere down the filter chain, // we still want to execute our after processing, and then // rethrow the problem after that. problem = t; t.printStackTrace(); } doAfterProcessing(request, response); // If there was a problem, we want to rethrow it if it is // a known type, otherwise log it. if (problem != null) { if (problem instanceof ServletException) { throw (ServletException) problem; } if (problem instanceof IOException) { throw (IOException) problem; } sendProcessingError(problem, response); } } /** * Return the filter configuration object for this filter. */ public FilterConfig getFilterConfig() { return (this.filterConfig); } /** * Set the filter configuration object for this filter. * * @param filterConfig The filter configuration object */ public void setFilterConfig(FilterConfig filterConfig) { this.filterConfig = filterConfig; } /** * Destroy method for this filter */ @Override public void destroy() { } /** * Init method for this filter */ @Override public void init(FilterConfig filterConfig) { this.filterConfig = filterConfig; if (filterConfig != null) { if (debug) { log("LoggingFilter:Initializing filter"); } } } /** * Return a String representation of this object. */ @Override public String toString() { if (filterConfig == null) { return ("LoggingFilter()"); } StringBuilder sb = new StringBuilder("LoggingFilter("); sb.append(filterConfig); sb.append(")"); return (sb.toString()); } private void sendProcessingError(Throwable t, ServletResponse response) { String stackTrace = getStackTrace(t); if (stackTrace != null && !stackTrace.equals("")) { try { response.setContentType("text/html"); try (PrintStream ps = new PrintStream(response.getOutputStream()); PrintWriter pw = new PrintWriter(ps)) { pw.