001/* 002 * ==================================================================== 003 * Licensed to the Apache Software Foundation (ASF) under one 004 * or more contributor license agreements. See the NOTICE file 005 * distributed with this work for additional information 006 * regarding copyright ownership. The ASF licenses this file 007 * to you under the Apache License, Version 2.0 (the 008 * "License"); you may not use this file except in compliance 009 * with the License. You may obtain a copy of the License at 010 * 011 * http://www.apache.org/licenses/LICENSE-2.0 012 * 013 * Unless required by applicable law or agreed to in writing, 014 * software distributed under the License is distributed on an 015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 016 * KIND, either express or implied. See the License for the 017 * specific language governing permissions and limitations 018 * under the License. 019 * ==================================================================== 020 * 021 * This software consists of voluntary contributions made by many 022 * individuals on behalf of the Apache Software Foundation. For more 023 * information on the Apache Software Foundation, please see 024 * <http://www.apache.org/>. 025 * 026 */ 027 028package org.apache.http.protocol; 029 030import java.io.IOException; 031 032import org.apache.http.HttpException; 033import org.apache.http.HttpRequest; 034import org.apache.http.HttpRequestInterceptor; 035import org.apache.http.annotation.ThreadingBehavior; 036import org.apache.http.annotation.Contract; 037import org.apache.http.params.CoreProtocolPNames; 038import org.apache.http.params.HttpParams; 039import org.apache.http.util.Args; 040 041/** 042 * RequestUserAgent is responsible for adding {@code User-Agent} header. 043 * This interceptor is recommended for client side protocol processors. 044 * 045 * @since 4.0 046 */ 047@SuppressWarnings("deprecation") 048@Contract(threading = ThreadingBehavior.IMMUTABLE) 049public class RequestUserAgent implements HttpRequestInterceptor { 050 051 private final String userAgent; 052 053 public RequestUserAgent(final String userAgent) { 054 super(); 055 this.userAgent = userAgent; 056 } 057 058 public RequestUserAgent() { 059 this(null); 060 } 061 062 @Override 063 public void process(final HttpRequest request, final HttpContext context) 064 throws HttpException, IOException { 065 Args.notNull(request, "HTTP request"); 066 if (!request.containsHeader(HTTP.USER_AGENT)) { 067 String s = null; 068 final HttpParams params = request.getParams(); 069 if (params != null) { 070 s = (String) params.getParameter(CoreProtocolPNames.USER_AGENT); 071 } 072 if (s == null) { 073 s = this.userAgent; 074 } 075 if (s != null) { 076 request.addHeader(HTTP.USER_AGENT, s); 077 } 078 } 079 } 080 081}