code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC 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.
  
  package org.openqa.selenium.environment.webserver;
  
  import static java.net.HttpURLConnection.HTTP_OK;
  import static org.openqa.selenium.remote.http.Contents.string;
  import static org.openqa.selenium.remote.http.Contents.utf8String;
  
  import com.google.common.base.Splitter;
  import java.io.UncheckedIOException;
  import java.io.UnsupportedEncodingException;
  import java.net.URLDecoder;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  import org.openqa.selenium.remote.http.HttpHandler;
  import org.openqa.selenium.remote.http.HttpRequest;
  import org.openqa.selenium.remote.http.HttpResponse;
  
  class UploadHandler implements HttpHandler {
  
    @Override
    public HttpResponse execute(HttpRequest req) throws UncheckedIOException {
      HttpResponse res = new HttpResponse();
      res.setHeader("Content-Type", "text/html");
      res.setStatus(HTTP_OK);
  
      StringBuilder content = new StringBuilder();
  
      // I mean. Seriously. *sigh*
      try {
        String decoded = URLDecoder.decode(string(req), Charset.defaultCharset().displayName());
  
        String[] splits = decoded.split("\r\n");
  
        // First line is the boundary marker
        String boundary = splits[0];
        List<Map<String, Object>> allParts = new ArrayList<>();
        Map<String, Object> values = new HashMap<>();
        boolean inHeaders = true;
        for (int i = 1; i < splits.length; i++) {
          if ("".equals(splits[i])) {
            inHeaders = false;
            continue;
          }
  
          if (splits[i].startsWith(boundary)) {
            inHeaders = true;
            allParts.add(values);
            continue;
          }
  
          if (inHeaders && splits[i].toLowerCase().startsWith("content-disposition:")) {
            for (String keyValue :
                Splitter.on(';').trimResults().omitEmptyStrings().split(splits[i])) {
              Matcher matcher = Pattern.compile("(\\S+)\\s*=.*\"(.*?)\".*").matcher(keyValue);
              if (matcher.find()) {
                values.put(matcher.group(1), matcher.group(2));
              }
            }
          } else if (!inHeaders) {
            String c = (String) values.getOrDefault("content", "");
            c += splits[i];
            values.put("content", c);
          }
        }
  
        Object value =
            allParts.stream()
                .filter(map -> "upload".equals(map.get("name")))
                .findFirst()
                .map(map -> map.get("content"))
                .orElseThrow(() -> new RuntimeException("Cannot find uploaded data"));
  
        content.append(value);
      } catch (UnsupportedEncodingException e) {
        throw new UncheckedIOException(e);
      }
  
      // Slow down the upload so we can verify WebDriver waits.
      try {
        Thread.sleep(2500);
      } catch (InterruptedException ignored) {
      }
  
      content.append("<script>window.top.window.onUploadDone();</script>");
  
      res.setContent(utf8String(content.toString()));
  
      return res;
    }
  }
  