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Java example source code file (ContinuingHttpServletRequest.java)

This example Java source code file (ContinuingHttpServletRequest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cannot, continuinghttpservletrequest, cookie, http, httpservletrequestwrapper, httpsession, immutablecookie, ioexception, map, object, outofscopeexception, override, request, response, servlet, servletinputstream, unsupportedoperationexception, util

The ContinuingHttpServletRequest.java Java example source code

/**
 * Copyright (C) 2010 Google Inc.
 *
 * Licensed 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 com.google.inject.servlet;

import com.google.common.collect.Maps;
import com.google.inject.OutOfScopeException;

import java.io.IOException;
import java.util.Map;

import javax.servlet.ServletInputStream;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpSession;

/**
 * A wrapper for requests that makes requests immutable, taking a snapshot
 * of the original request.
 *
 * @author dhanji@gmail.com (Dhanji R. Prasanna)
 */
class ContinuingHttpServletRequest extends HttpServletRequestWrapper {

  // We clear out the attributes as they are mutable and not thread-safe.
  private final Map<String, Object> attributes = Maps.newHashMap();
  private final Cookie[] cookies;

  public ContinuingHttpServletRequest(HttpServletRequest request) {
    super(request);

    Cookie[] originalCookies = request.getCookies();
    if (originalCookies != null) {
      int numberOfCookies = originalCookies.length;
      cookies = new Cookie[numberOfCookies];
      for (int i = 0; i < numberOfCookies; i++) {
        Cookie originalCookie = originalCookies[i];

        // Snapshot each cookie + freeze.
        // No snapshot is required if this is a snapshot of a snapshot(!)
        if (originalCookie instanceof ImmutableCookie) {
          cookies[i] = originalCookie;
        } else {
          cookies[i] = new ImmutableCookie(originalCookie);
        }
      }
    } else {
      cookies = null;
    }
  }

  @Override public HttpSession getSession() {
    throw new OutOfScopeException("Cannot access the session in a continued request");
  }

  @Override public HttpSession getSession(boolean create) {
    throw new UnsupportedOperationException("Cannot access the session in a continued request");
  }

  @Override public ServletInputStream getInputStream() throws IOException {
    throw new UnsupportedOperationException("Cannot access raw request on a continued request");
  }

  @Override public void setAttribute(String name, Object o) {
    attributes.put(name, o);
  }

  @Override public void removeAttribute(String name) {
    attributes.remove(name);
  }

  @Override public Object getAttribute(String name) {
    return attributes.get(name);
  }

  @Override public Cookie[] getCookies() {
    // NOTE(dhanji): Cookies themselves are mutable. However a ContinuingHttpServletRequest
    // snapshots the original set of cookies it received and imprisons them in immutable
    // form. Unfortunately, the cookie array itself is mutable and there is no way for us
    // to avoid this. At worst, however, mutation effects are restricted within the scope
    // of a single request. Continued requests are not affected after snapshot time.
    return cookies;
  }

  private static final class ImmutableCookie extends Cookie {
    public ImmutableCookie(Cookie original) {
      super(original.getName(), original.getValue());

      super.setMaxAge(original.getMaxAge());
      super.setPath(original.getPath());
      super.setComment(original.getComment());
      super.setSecure(original.getSecure());
      super.setValue(original.getValue());
      super.setVersion(original.getVersion());

      if (original.getDomain() != null) {
        super.setDomain(original.getDomain());
      }
    }

    @Override public void setComment(String purpose) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }

    @Override public void setDomain(String pattern) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }

    @Override public void setMaxAge(int expiry) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }

    @Override public void setPath(String uri) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }

    @Override public void setSecure(boolean flag) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }

    @Override public void setValue(String newValue) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }

    @Override public void setVersion(int v) {
      throw new UnsupportedOperationException("Cannot modify cookies on a continued request");
    }
  }
}

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