package com.qidou.httpclient;

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 java.util.Set;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
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.client.methods.HttpUriRequest;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.apache.log4j.Logger;

/**
 * HTTP請求客戶端，提供GET和POST兩種方式傳送請求。
 * 
 * @author Administrator
 *
 */
public class HttpClient 
{
	/**
	 * 日誌物件。
	 */
	private static Logger logger = Logger.getLogger(HttpClient.class);
	
	/**
	 * 預設HTTP請求客戶端物件。
	 */
	private DefaultHttpClient _httpclient;

	/**
	 * 使用者自定義訊息頭。
	 */
	private Map<String, String> _headers;

	/**
	 * 使用預設客戶端物件。
	 */
	public HttpClient() 
	{
		// 1. 建立HttpClient物件。
		_httpclient = new DefaultHttpClient();
		logger.info("create _httpclient ...");
	}

	/**
	 * 呼叫者指定客戶端物件。
	 * 
	 * @param httpclient
	 */
	public HttpClient(Map<String, String> headers) 
	{
		// 1. 建立HttpClient物件。
		_httpclient = new DefaultHttpClient();
		this._headers = headers;
		logger.info("create _httpclient ...");
	}

	/**
	 * HTTP POST請求。
	 * 
	 * @param url
	 * @param params
	 * @return
	 * @throws InterruptedException
	 */
	public HttpResponse post(String url, Map<String, String> params)
	{
		// 2. 建立請求方法的例項，並指定請求URL，新增請求引數。
		HttpPost post = postForm(url, params);
		logger.info("create httppost : " + url);
		
		return invoke(post);
	}

	/**
	 * HTTP GET請求。
	 * 
	 * @param url
	 * @return
	 */
	public HttpResponse get(String url) 
	{
		HttpGet get = new HttpGet(url);
		logger.info("create httpget : " + url);
		
		return invoke(get);
	}
	
	/**
	 * 傳送請求，處理響應。
	 * @param request
	 * @return
	 */
	private HttpResponse invoke(HttpUriRequest request)
	{
		if (this._headers != null) 
		{
			//
			addHeaders(request);
			logger.info("addHeaders to http ...");
		}
		
		HttpResponse response = null;
		try
		{
			// 3. 呼叫HttpClient物件的execute(HttpUriRequest request)傳送請求，返回一個HttpResponse。
			response = _httpclient.execute(request);
			logger.info("execute http success... ; body = " + EntityUtils.toString(response.getEntity()));
		}
		catch (Exception e)
		{
			e.printStackTrace();
			logger.info("execute http exception...");
		}
		finally
		{
			// 4. 無論執行方法是否成功，都必須釋放連線。
			request.abort();
			logger.info("release http ...");
		}
		
		return response;
	}
	
	/**
	 * 獲取post方法。
	 * 
	 * @param url
	 * @param params
	 * @return
	 */
	private HttpPost postForm(String url, Map<String, String> params) 
	{
		HttpPost httpost = new HttpPost(url);
		List<NameValuePair> nvps = new ArrayList<NameValuePair>();

		// 組裝引數。
		Set<String> keySet = params.keySet();
		for (String key : keySet) 
		{
			nvps.add(new BasicNameValuePair(key, params.get(key)));
		}

		try 
		{
			logger.info("set utf-8 form entity to httppost ...");
			httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));
		}
		catch (UnsupportedEncodingException e)
		{
			e.printStackTrace();
		}

		return httpost;
	}
	
	/**
	 * 增加訊息頭。
	 * 
	 * @param httpost
	 */
	private void addHeaders(HttpUriRequest httpost)
	{
		Iterator<Entry<String, String>> it = this._headers.entrySet()
				.iterator();
		Entry<String, String> entry = null;
		String name = null;
		String value = null;

		while (it.hasNext())
		{
			entry = it.next();
			name = entry.getKey();
			value = entry.getValue();

			httpost.addHeader(name, value);
		}
	}
	
	/**
	 * 關閉HTTP客戶端連結。
	 */
	public void shutdown()
	{
		_httpclient.getConnectionManager().shutdown();
		logger.info("shutdown _httpclient ...");
	}
}
 

三、測試示例