標籤：
如果在一個Tomcat Server上會部署多個Web應用，又希望這多個Web應用共用一套錯誤頁面，而不是使用預設的錯誤頁面。就需要自訂錯誤頁面了。
在每個web應用中都可以通過error-page來配置錯誤頁面。但是多個Web應用時，要在每個應用的web.xml中都配置一個錯誤頁面，就顯得有些麻煩了。然而希望通過在tomcat/conf/web.xml中來配置錯誤頁面，是不能實現的。因為Tomcat部署應用時會將公用的web.xml與每個web應用的web.xml進行合并，尋找頁面時，其實還是在每個web應用的目錄下尋找的。
為了達到共用的目錄，只能自己來重寫Tomcat的預設實現了。所幸，Tomcat也是支援我們這樣去做的。
package com.fjn.frame.catalina.valves;import java.io.IOException;import java.io.InputStream;import java.io.Writer;import java.util.Scanner;import org.apache.catalina.connector.Request;import org.apache.catalina.connector.Response;import org.apache.catalina.util.RequestUtil;import org.apache.catalina.util.ServerInfo;import org.apache.catalina.valves.ErrorReportValve;/** * * 要使用這個類來自訂錯誤頁面，需要調整 server.xml中Host的errorReportValveClass屬性值為這個類。 * 另外需要將這個類打成jar包放在tomcat/lib目錄下。 * @since tomcat 6.0 * @author [email protected] 2015年6月4日 * */public class ErrorPageValve extends ErrorReportValve { private static final String ERROR_PAGE_NAME = "errorPage.html"; @Override protected void report(Request request, Response response, Throwable throwable) { // Do nothing on non-HTTP responses int statusCode = response.getStatus(); // Do nothing on a 1xx, 2xx and 3xx status // Do nothing if anything has been written already if (statusCode < 400 || response.getContentCount() > 0 || !response.isError()) { return; } String message = RequestUtil.filter(response.getMessage()); if (message == null) { if (throwable != null) { String exceptionMessage = throwable.getMessage(); if (exceptionMessage != null && exceptionMessage.length() > 0) { message = RequestUtil .filter((new Scanner(exceptionMessage)).nextLine()); } } if (message == null) { message = ""; } } // Do nothing if there is no report for the specified status code String report = null; try { report = sm.getString("http." + statusCode); } catch (Throwable t) { ; } if (report == null) return; StringBuffer sb = new StringBuffer(); try { buildHTMLFromErrorPage(sb); } catch (Exception ex) { } if (sb.length() < 1) { defaultBuildHTML(sb, statusCode, message, report, throwable); } try { try { response.setContentType("text/html"); response.setCharacterEncoding("utf-8"); } catch (Throwable t) { if (container.getLogger().isDebugEnabled()) container.getLogger().debug("status.setContentType", t); } Writer writer = response.getReporter(); if (writer != null) { // If writer is null, it‘s an indication that the response has // been hard committed already, which should never happen writer.write(sb.toString()); } } catch (IOException e) { ; } catch (IllegalStateException e) { ; } } private void defaultBuildHTML(StringBuffer sb, int statusCode, String message, String report, Throwable throwable) { sb.append("<html><head><title>"); sb.append(ServerInfo.getServerInfo()).append(" - "); sb.append(sm.getString("errorReportValve.errorReport")); sb.append("</title>"); sb.append("<style><!--"); sb.append(org.apache.catalina.util.TomcatCSS.TOMCAT_CSS); sb.append("--></style> "); sb.append("</head><body>"); sb.append("<h1>"); sb.append( sm.getString("errorReportValve.statusHeader", "" + statusCode, message)).append("</h1>"); sb.append("<HR size=\"1\" noshade=\"noshade\">"); sb.append("<p><b>type</b> "); if (throwable != null) { sb.append(sm.getString("errorReportValve.exceptionReport")); } else { sb.append(sm.getString("errorReportValve.statusReport")); } sb.append("</p>"); sb.append("<p><b>"); sb.append(sm.getString("errorReportValve.message")); sb.append("</b> <u>"); sb.append(message).append("</u></p>"); sb.append("<p><b>"); sb.append(sm.getString("errorReportValve.description")); sb.append("</b> <u>"); sb.append(report); sb.append("</u></p>"); if (throwable != null) { String stackTrace = getPartialServletStackTrace(throwable); sb.append("<p><b>"); sb.append(sm.getString("errorReportValve.exception")); sb.append("</b> <pre>"); sb.append(RequestUtil.filter(stackTrace)); sb.append("</pre></p>"); int loops = 0; Throwable rootCause = throwable.getCause(); while (rootCause != null && (loops < 10)) { stackTrace = getPartialServletStackTrace(rootCause); sb.append("<p><b>"); sb.append(sm.getString("errorReportValve.rootCause")); sb.append("</b> <pre>"); sb.append(RequestUtil.filter(stackTrace)); sb.append("</pre></p>"); // In case root cause is somehow heavily nested rootCause = rootCause.getCause(); loops++; } sb.append("<p><b>"); sb.append(sm.getString("errorReportValve.note")); sb.append("</b> <u>"); sb.append(sm.getString("errorReportValve.rootCauseInLogs", ServerInfo.getServerInfo())); sb.append("</u></p>"); } sb.append("<HR size=\"1\" noshade=\"noshade\">"); sb.append("<h3>").append(ServerInfo.getServerInfo()).append("</h3>"); sb.append("</body></html>"); } private void buildHTMLFromErrorPage(StringBuffer buffer) throws IOException { InputStream in=null; Scanner scanner = null; try { // 優先從當前路徑下尋找檔案 in=this.getClass().getResourceAsStream(ERROR_PAGE_NAME); if(in==null){ // 從當前jar包內的根目錄 或者tomcat/lib目錄下 in=Thread.currentThread().getContextClassLoader().getResourceAsStream(ERROR_PAGE_NAME); } if(in==null){ in=ClassLoader.getSystemResourceAsStream(ERROR_PAGE_NAME); } scanner = new Scanner(in); while (scanner.hasNextLine()) { String line = scanner.nextLine(); // line=RequestUtil.filter(line); buffer.append(line); } } catch (Exception ex) { } finally { if (scanner != null) { scanner.close(); } if(in!=null){ in.close(); } } } }
Tomcat：Custom a common error page valve for all web application in tomcat
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