httpclient使用详解（爬虫）

一、简介

HttpClient是Apache Jakarta Common下的子项目，用来提供高效的、最新的、功能丰富的支持HTTP协议的客户端编程工具包，并且它支持HTTP协议最新的版本和建议。HttpClient已经应用在很多的项目中，比如Apache Jakarta上很著名的另外两个开源项目Cactus和HTMLUnit都使用了HttpClient。
下载地址: http://hc.apache.org/downloads.cgi

二、特性

1. 基于标准、纯净的java语言。实现了Http1.0和Http1.1
2. 以可扩展的面向对象的结构实现了Http全部的方法（GET, POST, PUT, DELETE, HEAD, OPTIONS, and TRACE）。
3. 支持HTTPS协议。
4. 通过Http代理建立透明的连接。
5. 利用CONNECT方法通过Http代理建立隧道的https连接。
6. Basic, Digest, NTLMv1, NTLMv2, NTLM2 Session, SNPNEGO/Kerberos认证方案。
7. 插件式的自定义认证方案。
8. 便携可靠的套接字工厂使它更容易的使用第三方解决方案。
9. 连接管理器支持多线程应用。支持设置最大连接数，同时支持设置每个主机的最大连接数，发现并关闭过期的连接。
10. 自动处理Set-Cookie中的Cookie。
11. 插件式的自定义Cookie策略。
12. Request的输出流可以避免流中内容直接缓冲到socket服务器。
13. Response的输入流可以有效的从socket服务器直接读取相应内容。
14. 在http1.0和http1.1中利用KeepAlive保持持久连接。
15. 直接获取服务器发送的response code和 headers。
16. 设置连接超时的能力。
17. 实验性的支持http1.1 response caching。
18. 源代码基于Apache License 可免费获取。

三、使用方法

使用HttpClient发送请求、接收响应很简单，一般需要如下几步即可。

1. 创建HttpClient对象。
2. 创建请求方法的实例，并指定请求URL。如果需要发送GET请求，创建HttpGet对象；如果需要发送POST请求，创建HttpPost对象。
3. 如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。
4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求，该方法返回一个HttpResponse。
5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。
6. 释放连接。无论执行方法是否成功，都必须释放连接

四、样例

HttpClientRequestHandler类

package com.xiaojiang.httpclient;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.zip.GZIPInputStream;

import org.apache.commons.io.IOUtils;
import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import com.xiaojiang.exception.DataTaskException;

public class HttpClientRequestHandler {

private static final int ERROR_CODE = 1;

/**
* get方式提交数据
*/
public static Document doGet(String url, String proxyIp, Integer proxyPort) throws DataTaskException{

//System.out.println("doGet中使用代理："+proxyIp+":"+proxyPort);

HttpClient client = HttpConnectionManager.getHttpClient(proxyIp, proxyPort);

HttpGet httpGet = new HttpGet(url);
httpGet.setHeader("Accept-Language", "zh-cn,zh;q=0.5");
httpGet.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");
httpGet.setHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
httpGet.setHeader("Accept-Encoding", "gzip, deflate");
httpGet.setHeader("User-Agent", HttpUserAgent.get());

try{
//执行
HttpResponse response = client.execute(httpGet);
int statuCode = response.getStatusLine().getStatusCode();
if(statuCode == 200){
String html = formatResponse(response);

if(html != null){
return Jsoup.parse(html);
}
return null;

} else {
throw new DataTaskException(statuCode, "请求URL【"+url+"】，"+statuCode+"错误", null);
}
} catch (Exception e){
throw new DataTaskException(ERROR_CODE, e.getMessage(), e);
} finally {
if(httpGet != null){
httpGet.abort();
}
}
}

/**
* post方式提交
* @throws DataTaskException
*/
public static Document doPost(String url, Map<String,String> paramaters, String proxyIp, Integer proxyPort) throws DataTaskException{

HttpClient client = HttpConnectionManager.getHttpClient(proxyIp, proxyPort);

HttpPost request = new HttpPost(url);

request.setHeader("Accept", "application/json, text/javascript, */*; q=0.01");
request.setHeader("Accept-Encoding", "gzip, deflate");
request.setHeader("Accept-Language", "zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3");
request.setHeader("Cache-Control", "no-cache");
request.setHeader("Connection", "keep-alive");
request.setHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");

// 创建名/值组列表
List<NameValuePair> parameters = new ArrayList<NameValuePair>();
for(String key : paramaters.keySet()){
parameters.add(new BasicNameValuePair(key, paramaters.get(key)));
}

try {
// 创建UrlEncodedFormEntity对象
UrlEncodedFormEntity formEntiry = new UrlEncodedFormEntity(parameters);
request.setEntity(formEntiry);

// 执行请求
HttpResponse response = client.execute(request);
int statuCode = response.getStatusLine().getStatusCode();

if (statuCode == 200) {
String html = formatResponse(response);

if(html != null){
return Jsoup.parse(html);
}

return null;

} else if (statuCode == 404) {

throw new DataTaskException(ERROR_CODE, "请求URL【"+url+"】，404错误", null);
}
} catch (Exception e) {

throw new DataTaskException(ERROR_CODE, e.getMessage(), e);

} finally {
if(request != null){
request.abort();
}
}
return null;
}

/**
* 格式化请求结果
* @throws DataTaskException
*/
private static String formatResponse(HttpResponse response) throws DataTaskException {

ByteArrayInputStream bis = null;
try{
Header contentEncoding = response.getFirstHeader("Content-Encoding");

if(contentEncoding == null){
return EntityUtils.toString(response.getEntity(),"UTF-8");
} else {

String charset = "utf-8";
Header contentType = response.getFirstHeader("Content-Type");

if(contentType != null){
String contentTypeStr = contentType.getValue();
if(contentTypeStr != null && !"".equals(contentTypeStr)){
charset = contentTypeStr.substring(contentTypeStr.indexOf("=") + 1,contentTypeStr.length());

}
}

String contentEncodingType = contentEncoding.getValue();
if(contentEncodingType.equalsIgnoreCase("gzip")){
if(response.toString().contains("soufun"))
charset = "gb2312";

byte[] bytes = IOUtils.toByteArray(response.getEntity().getContent());
bis = new ByteArrayInputStream(bytes);

return uncompress(bis ,charset);
}

}

} catch(Exception e) {
throw new DataTaskException(ERROR_CODE, "格式化HttpResponse出错", e);
} finally {
if(bis != null){
try {
bis.close();
} catch (IOException e) {
throw new DataTaskException(ERROR_CODE, "格式化HttpResponse出错", e);
}
}
}

return null;
}

/**
* GZIP解压
*/
private static String uncompress(ByteArrayInputStream in, String charset) {

ByteArrayOutputStream out = new ByteArrayOutputStream();

try {
GZIPInputStream gunzip = new GZIPInputStream(in);
byte[] buffer = new byte[256];
int n;
while((n = gunzip.read(buffer)) >=0 ){
out.write(buffer, 0, n);
}
return out.toString(charset);

} catch (IOException e) {
e.printStackTrace();
}
return null;
}

}

HttpConnectionManager类

package com.xiaojiang.httpclient;

import org.apache.http.HttpHost;
import org.apache.http.client.HttpClient;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.conn.params.ConnPerRouteBean;
import org.apache.http.conn.params.ConnRouteParams;
import org.apache.http.conn.scheme.PlainSocketFactory;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;

public class HttpConnectionManager {

private static HttpParams httpParams;
private static ClientConnectionManager connectionManager;

//最大连接数
public final static int MAX_TOTAL_CONNECTIONS = 800;

//获取连接的最大等待时间
public final static int WAIT_TIMEOUT = 60000;

//每个路由最大连接数
public final static int MAX_ROUTE_CONNECTIONS = 400;

//连接超时时间
public final static int CONNECT_TIMEOUT = 60000;

//读取超时时间
public final static int READ_TIMEOUT = 60000;

static {
httpParams = new BasicHttpParams();
// 设置最大连接数
ConnManagerParams.setMaxTotalConnections(httpParams, MAX_TOTAL_CONNECTIONS);
// 设置获取连接的最大等待时间
ConnManagerParams.setTimeout(httpParams, WAIT_TIMEOUT);
// 设置每个路由最大连接数
ConnPerRouteBean connPerRoute = new ConnPerRouteBean(MAX_ROUTE_CONNECTIONS);
ConnManagerParams.setMaxConnectionsPerRoute(httpParams,connPerRoute);

// 设置连接超时时间
HttpConnectionParams.setConnectionTimeout(httpParams, CONNECT_TIMEOUT);
// 设置读取超时时间
HttpConnectionParams.setSoTimeout(httpParams, READ_TIMEOUT);

SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443));

connectionManager = new ThreadSafeClientConnManager(httpParams, registry);
}

public static HttpClient getHttpClient(String proxyIp, Integer proxyPort){
DefaultHttpClient client = new DefaultHttpClient(connectionManager, httpParams);

if(proxyIp !=null && proxyPort !=null){
HttpHost proxy = new HttpHost(proxyIp, proxyPort);
client.getParams().setParameter(ConnRouteParams.DEFAULT_PROXY, proxy);
}
return client;
}

}

HttpUserAgent类package com.xiaojiang.httpclient;

package com.xiaojiang.httpclient;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class HttpUserAgent {

private static List<String> agents;

static{
agents = new ArrayList<String>();

//IE
agents.add("Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0)");
agents.add("Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2)");
agents.add("Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)");
agents.add("Mozilla/4.0 (compatible; MSIE 5.0; Windows NT)");

//Firefox
agents.add("Mozilla/5.0 (Windows; U; Windows NT 5.2) Gecko/2008070208 Firefox/3.0.1 ");
agents.add("Mozilla/5.0 (Windows; U; Windows NT 5.1) Gecko/20070309 Firefox/2.0.0.3 ");
agents.add("Mozilla/5.0 (Windows; U; Windows NT 5.1) Gecko/20070803 Firefox/1.5.0.12");
agents.add("Mozilla/5.0 (Windows NT 6.3; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0)");
agents.add("Mozilla/5.0 (Windows NT 5.1; rv:5.0) Gecko/20100101 Firefox/5.0");

//Opera
agents.add("Opera/9.27 (Windows NT 5.2; U; zh-cn)");
agents.add("Opera/8.0 (Macintosh; PPC Mac OS X; U; en)");
agents.add("Mozilla/5.0 (Macintosh; PPC Mac OS X; U; en) Opera 8.0");

//Safari
agents.add("Mozilla/5.0 (Windows; U; Windows NT 5.2) AppleWebKit/525.13 (KHTML, like Gecko) Version/3.1 Safari/525.13");
agents.add("Mozilla/5.0 (iPhone; U; CPU like Mac OS X) AppleWebKit/420.1 (KHTML, like Gecko) Version/3.0 Mobile/4A93 Safari/419.3");

//Chrome
agents.add("Mozilla/5.0 (Windows; U; Windows NT 5.2) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.27 Safari/525.13");
agents.add("Mozilla/5.0 (Windows NT 5.2) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30");

//Navigator
agents.add("Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.12) Gecko/20080219 Firefox/2.0.0.12 Navigator/9.0.0.6");

//360极速浏览器
agents.add("Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) ;  QIHU 360EE)");

}

public static String get(){
return agents.get(new Random().nextInt(agents.size()-1));
}
}