/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.Locale;
import java.util.ResourceBundle;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import org.apache.tomcat.util.json.JSONFilter;
import util.CookieFilter;
import util.HTMLFilter;
/**
* Example servlet showing request headers
*/
public class RequestHeaderExample extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
if (prefersJSON(request.getHeader("Accept"))) {
renderJSON(request, response);
} else {
renderHTML(request, response);
}
}
/**
* Returns true if the client appears to prefer a JSON response, false otherwise. Note that this method is not very
* pedantic and uses only a very lazy algorithm for checking whether JSON is "preferred".
*
* @param acceptHeader The value of the HTTP "Accept" header from the client.
*
* @return true if the client appears to prefer a JSON response, false otherwise.
*/
protected boolean prefersJSON(String acceptHeader) {
if (null == acceptHeader) {
return false;
}
// mime/type, mime/type;q=n, ...
// Don't bother with the q-factor.
// This is not expected to be 100% accurate or spec-compliant
String[] accepts = acceptHeader.split(",");
for (String accept : accepts) {
if (accept.contains("application/json")) {
return true;
}
// text/html, application/html, etc.
if (accept.contains("html")) {
return false;
}
}
return false;
}
protected void renderHTML(HttpServletRequest request, HttpServletResponse response) throws IOException {
ResourceBundle rb = ResourceBundle.getBundle("LocalStrings", request.getLocale());
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE html><html>");
out.println("<head>");
out.println("<meta charset=\"UTF-8\" />");
String title = rb.getString("requestheader.title");
out.println("<title>" + title + "</title>");
out.println("</head>");
out.println("<body bgcolor=\"white\">");
out.println("<a href=\"../reqheaders.html\">");
out.println(
"<img src=\"../images/code.gif\" height=24 " + "width=24 align=right border=0 alt=\"view code\"></a>");
out.println("<a href=\"../index.html\">");
out.println(
"<img src=\"../images/return.gif\" height=24 " + "width=24 align=right border=0 alt=\"return\"></a>");
out.println("<h3>" + title + "</h3>");
out.println("<table border=0>");
Enumeration<String> e = request.getHeaderNames();
while (e.hasMoreElements()) {
String headerName = e.nextElement();
String headerValue = request.getHeader(headerName);
out.println("<tr><td bgcolor=\"#CCCCCC\">");
out.println(HTMLFilter.filter(headerName));
out.println("</td><td>");
if (headerName.toLowerCase(Locale.ENGLISH).contains("cookie")) {
HttpSession session = request.getSession(false);
String sessionId = null;
if (session != null) {
sessionId = session.getId();
}
out.println(HTMLFilter.filter(CookieFilter.filter(headerValue, sessionId)));
} else {
out.println(HTMLFilter.filter(headerValue));
}
out.println("</td></tr>");
}
out.println("</table>");
}
protected void renderJSON(HttpServletRequest request, HttpServletResponse response) throws IOException {
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
out.append('[');
Enumeration<String> e = request.getHeaderNames();
while (e.hasMoreElements()) {
String headerName = e.nextElement();
String headerValue = request.getHeader(headerName);
out.append("{\"").append(JSONFilter.escape(headerName)).append("\":\"");
if (headerName.toLowerCase(Locale.ENGLISH).contains("cookie")) {
HttpSession session = request.getSession(false);
String sessionId = null;
if (session != null) {
sessionId = session.getId();
}
out.append(JSONFilter.escape(CookieFilter.filter(headerValue, sessionId)));
} else {
out.append(JSONFilter.escape(headerValue));
}
out.append("\"}");
if (e.hasMoreElements()) {
out.append(',');
}
}
out.print("]");
}
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
doGet(request, response);
}
}