如果在一个Tomcat Server上会部署多个Web应用，又希望这多个Web应用共用一套错误页面，而不是使用默认的错误页面。就需要自定义错误页面了。
在每个web应用中都可以通过error-page来配置错误页面。但是多个Web应用时，要在每个应用的web.xml中都配置一个错误页面，就显得有些麻烦了。然而希望通过在tomcat/conf/web.xml中来配置错误页面，是不能实现的。因为Tomcat部署应用时会将公共的web.xml与每个web应用的web.xml进行合并，查找页面时，其实还是在每个web应用的目录下查找的。
为了达到共用的目录，只能自己来重写Tomcat的默认实现了。所幸，Tomcat也是支持我们这样去做的。
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;
/**
*
* 要使用这个类来自定义错误页面，需要调整 server.xml中Host的errorReportValveClass属性值为这个类。
* 另外需要将这个类打成jar包放在tomcat/lib目录下。
* @since tomcat 6.0
* @author fs1194361820@163.com 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 {
// 优先从当前路径下查找文件
in=this.getClass().getResourceAsStream(ERROR_PAGE_NAME);
if(in==null){
// 从当前jar包内的根目录 或者tomcat/lib目录下
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();
}
}
} }