httpclient4.2.2的几个常用方法，登录之后访问页面问题，下载文件

package ryan;

import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpVersion;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
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.conn.ClientConnectionManager;
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.cookie.Cookie;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HTTP;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;

public class HttpClientTotal
{

public static void getUrl(String url, String encoding)
throws ClientProtocolException, IOException
{
// 默认的Client类
HttpClient client = new DefaultHttpClient();
// 设置为get取连接的方式
HttpGet get = new HttpGet(url);
// 得到返回的Response
HttpResponse response = client.execute(get);
// 得到返回的Client里面的实体对象信息
HttpEntity entity = response.getEntity();
if (entity != null)
{
System.out.println("内容编码是：" + entity.getContentEncoding());
System.out.println("内容类型是: " + entity.getContentType());
// 得到返回主体内容
InputStream is = entity.getContent();
try
{
BufferedReader reader = new BufferedReader(
new InputStreamReader(is, encoding));
System.out.println(reader.readLine());
} catch (Exception e)
{
e.printStackTrace();
} finally
{
if (is != null) is.close();
}
}
// 关闭连接
client.getConnectionManager().shutdown();

}

// 简单使用POSt进行
public static void postUrlWithParams(String url,
Map<String, String> params, String encoding)
{
DefaultHttpClient client = new DefaultHttpClient();
try
{
HttpPost httpPost = new HttpPost(url);
// 添加参数
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
if (params != null && params.keySet().size() > 0)
{
Iterator iterator = params.entrySet().iterator();
while (iterator.hasNext())
{
Map.Entry<String, String> entry = (Entry) iterator.next();
nvps.add(new BasicNameValuePair(entry.getKey(), entry
.getValue()));
}
}

httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));
HttpResponse response = client.execute(httpPost);
HttpEntity entity = response.getEntity();
System.out.println("Login form get: " + response.getStatusLine()
+ entity.getContent());
dump(entity, encoding);
System.out.println("Post logon cookies:");
List<Cookie> cookies = client.getCookieStore().getCookies();
if (cookies.isEmpty())
{
System.out.println("None");
} else
{
for (int i = 0; i < cookies.size(); i++)
{
System.out.println("- " + cookies.get(i).toString());
}
}
} catch (UnsupportedEncodingException e)
{
e.printStackTrace();
} catch (ClientProtocolException e)
{
e.printStackTrace();
} catch (IOException e)
{
e.printStackTrace();
} finally
{
// 关闭请求
client.getConnectionManager().shutdown();
}
}

private static void dump(HttpEntity entity, String encoding)
throws IOException
{
BufferedReader br = new BufferedReader(new InputStreamReader(
entity.getContent(), encoding));
System.out.println(br.readLine());
}

/**
* 4.常见的登录session问题，需求:使用账户，密码登录系统之后，然后再访问页面不出错。
*
* @param url
* @param params
* @param encoding
* @param url2
* @return
* @throws Exception
*/
public static String getSessionId(String url, Map params, String encoding,
String url2) throws Exception
{
DefaultHttpClient httpClient = new DefaultHttpClient(
new ThreadSafeClientConnManager());
try
{

HttpPost httpPost = new HttpPost(url);
// 添加参数
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
if (params != null && params.keySet().size() > 0)
{
Iterator iterator = params.entrySet().iterator();
while (iterator.hasNext())
{
Map.Entry<String, String> entry = (Entry) iterator.next();
nvps.add(new BasicNameValuePair((String) entry.getKey(),
(String) entry.getValue()));

}
}
// 设置请求的编码格式
httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));
// 登陆一遍
httpClient.execute(httpPost);
httpPost = new HttpPost(url2);
BasicResponseHandler responseHandler = new BasicResponseHandler();
// 再登陆
System.out.println(httpClient.execute(httpPost, responseHandler));
} finally
{
// 关闭请求
httpClient.getConnectionManager().shutdown();
}
return "";
}

// 第一个参数，网络连接；第二个参数，保存到本地文件的地址
public static void getFile(String url, String fileName)
{
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(url);
try
{
ResponseHandler<byte[]> handler = new ResponseHandler<byte[]>()
{
public byte[] handleResponse(HttpResponse response)
throws ClientProtocolException, IOException
{
HttpEntity entity = response.getEntity();
if (entity != null)
{
return EntityUtils.toByteArray(entity);
} else
{
return null;
}
}
};

byte[] charts = client.execute(get, handler);
FileOutputStream out = new FileOutputStream(fileName);
out.write(charts);
out.close();

} catch (Exception e)
{
e.printStackTrace();
} finally
{

client.getConnectionManager().shutdown();
}
}

//	创建一个多线程环境下面可用的httpClient
private static HttpClient createHttpClient()
{
HttpParams params = new BasicHttpParams();
HttpProtocolParams.setVersion(params,HttpVersion.HTTP_1_1);
HttpProtocolParams.setContentCharset(params, HTTP.DEFAULT_CONTENT_CHARSET);
HttpProtocolParams.setUseExpectContinue(params, true);

SchemeRegistry schReg = new SchemeRegistry();
schReg.register(new Scheme("http",PlainSocketFactory.getSocketFactory(),80));
schReg.register(new Scheme("https",PlainSocketFactory.getSocketFactory(),433));
ClientConnectionManager conMgr = new ThreadSafeClientConnManager(params,schReg);

return new DefaultHttpClient(conMgr,params);
}

}