福建农林大学J2EE实验报告五.doc

福建农林大学计算机与信息学院实验报告系计算机与信息专业计算机科学与技术年级2013成绩姓名学号实验室机号实验时间教师签字实验（五） 过滤器和监听器一、实验目的和要求1. 掌握如何实现一个Servlet过滤器步骤二、实验内容和原理1. 自定义一个过滤器，用来过滤非法文字。如果用户提交的信息中含有非法文字，则使用“*”字符替代之前的非法字符。要求：编写3个文件，即 用来提交用户发言信息的表单 用来过滤非法文字的过滤器 显示过滤后的用户发言的页面三、实验环境1. 硬件环境：2. 软件环境：JDK1.5四、算法描述及实验步骤1. 算法描述（可以用流程图、伪代码或源程序描述）2. 实验步骤Index.html Handle.jsp 过滤后的内容 Web.xml CharFilter newpackage.CharFilter KeyWord0 fuck KeyWord1 bitch KeyWord2 fool CharFilter /* 30 newPackage.CharFilter.javapackage newpackage;import java.io.IOException;import java.io.PrintStream;import java.io.PrintWriter;import java.io.StringWriter;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;/* * * author Administrator */public class CharFilter implements Filter private static final boolean debug = true; private FilterConfig filterConfig = null; private String sKeyWords; public CharFilter() private void doBeforeProcessing(ServletRequest request, ServletResponse response) throws IOException, ServletException if (debug) log(CharFilter:DoBeforeProcessing); private void doAfterProcessing(ServletRequest request, ServletResponse response) throws IOException, ServletException if (debug) log(CharFilter:DoAfterProcessing); /* * * 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 */ public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException if (debug) log(CharFilter:doFilter(); doBeforeProcessing(request, response); /获取关键字 sKeyWords = new String3; sKeyWords0 = filterConfig.getInitParameter(KeyWord0); if(sKeyWords0 = null) sKeyWords0 = ; sKeyWords1 = filterConfig.getInitParameter(KeyWord1); if(sKeyWords1 = null) sKeyWords1 = ; sKeyWords2 = filterConfig.getInitParameter(KeyWord2); if(sKeyWords2 = null) sKeyWords2 = ; /获取输入 request.setCharacterEncoding(GB2312); String sInput = request.getParameter(input); if(sInput = null) chain.doFilter(request, response); return; for(int i = 0;i sKeyWords.length;i+) sInput = myReplace(sInput,sKeyWordsi,*); request.setAttribute(output, sInput);/送往下一个过滤器 Throwable problem = null; try chain.doFilter(request, response); catch (Throwable 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); public String myReplace(String sInput,String sKeyWord,char cReplace) if(sInput = null | sInput.isEmpty() System.exit(0); if(sKeyWord = null | sKeyWord.isEmpty() return sInput; int nlength = sKeyWord.length(); String sReplace = ; while(nlength != 0) sReplace = sReplace + Character.toString(cReplace); nlength-; /替换大写 return sInput.replaceAll(sKeyWord, sReplace); /* * 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() this.filterConfig = null; /* * Init method for this filter * param filterConfig */ Override public void init(FilterConfig filterConfig) this.filterConfig = filterConfig; if (filterConfig != null) if (debug) log(CharFilter:Initializing filter); /* * Return a String representation of this object. */ Override public String toString() if (filterConfig = null) return (CharFilter(); StringBuffer sb = new StringBuffer(CharFilter(); 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); PrintStream ps = new PrintStream(response.getOutputStream(); PrintWriter pw = new PrintWriter(ps); pw.print(nnErrornnn); /NOI18N / PENDING! Localize this for next official release pw.print(The resource did not process correctlynn); pw.print(stackTrace); pw.print(n); /NOI18N pw.close(); ps.close(); response.getOutputStream().close(); catch (Exception ex) else try PrintStream ps = new PrintStream(response.getOutputStream(); t.printStackTrace(ps); ps.close(); response.getOutputStream().close(); catch (Exception ex) public static String getStackTrace(Throwable t) String stackTrace = null; try StringWriter sw = new StringWriter(); PrintWriter pw = new PrintWriter(sw); t.printStackTrace(pw); pw.close(); sw.close();