基于HttpClient的HttpUtils(后台访问URL)

原文：http://lxy19791111.iteye.com/blog/341409

      最近做在线支付时遇到需要以后台方式访问URL并获取其返回的数据的问题，在网络上g了一把，发现在常用的还是Apache的HttpClient。因为以经常要用到的原故，因此我对其进行了一些简单的封装，在此将代码贴一来，希望对有需要的朋友有所帮助，呵呵...

      HttpUtils.java中有两个公共的静态方法，一个是URLPost，另一个是URLGet，一目了然，前者是提供POST方式提交数据的，后者是提供GET方式提交数据的。其中所需要传送的数据以Map的方式传入，剩下的工作就交给我这个HttpUtils吧！当然如果Http服务器端对所提交的数据的编码有要求的话，也没问题，你可以传入UTF-8或者GBK，当然大家还可自行增加。

      下面是源代码，如果使用中有什么问题，欢迎大家提出。

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * HTTP工具类
 * 
 * @author lixiangyang
 * 
 */
public class HttpUtils {

	private static Log log = LogFactory.getLog(HttpUtils.class);
	
	/**
	 * 定义编码格式 UTF-8
	 */
	public static final String URL_PARAM_DECODECHARSET_UTF8 = "UTF-8";
	
	/**
	 * 定义编码格式 GBK
	 */
	public static final String URL_PARAM_DECODECHARSET_GBK = "GBK";
	
	private static final String URL_PARAM_CONNECT_FLAG = "&";
	
	private static final String EMPTY = "";

	private static MultiThreadedHttpConnectionManager connectionManager = null;

	private static int connectionTimeOut = 25000;

	private static int socketTimeOut = 25000;

	private static int maxConnectionPerHost = 20;

	private static int maxTotalConnections = 20;

	private static HttpClient client;

	static{
		connectionManager = new MultiThreadedHttpConnectionManager();
		connectionManager.getParams().setConnectionTimeout(connectionTimeOut);
		connectionManager.getParams().setSoTimeout(socketTimeOut);
		connectionManager.getParams().setDefaultMaxConnectionsPerHost(maxConnectionPerHost);
		connectionManager.getParams().setMaxTotalConnections(maxTotalConnections);
		client = new HttpClient(connectionManager);
	}
	
	/**
	 * POST方式提交数据
	 * @param url
	 * 			待请求的URL
	 * @param params
	 * 			要提交的数据
	 * @param enc
	 * 			编码
	 * @return
	 * 			响应结果
	 * @throws IOException
	 * 			IO异常
	 */
	public static String URLPost(String url, Map<String, String> params, String enc){

		String response = EMPTY;		
		PostMethod postMethod = null;
		try {
			postMethod = new PostMethod(url);
			postMethod.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=" + enc);
			//将表单的值放入postMethod中
			Set<String> keySet = params.keySet();
			for(String key : keySet){
				String value = params.get(key);
				postMethod.addParameter(key, value);
			}			
			//执行postMethod
			int statusCode = client.executeMethod(postMethod);
			if(statusCode == HttpStatus.SC_OK) {
				response = postMethod.getResponseBodyAsString();
			}else{
				log.error("响应状态码 = " + postMethod.getStatusCode());
			}
		}catch(HttpException e){
			log.error("发生致命的异常，可能是协议不对或者返回的内容有问题", e);
			e.printStackTrace();
		}catch(IOException e){
			log.error("发生网络异常", e);
			e.printStackTrace();
		}finally{
			if(postMethod != null){
				postMethod.releaseConnection();
				postMethod = null;
			}
		}
		
		return response;
	}
	
	/**
	 * GET方式提交数据
	 * @param url
	 * 			待请求的URL
	 * @param params
	 * 			要提交的数据
	 * @param enc
	 * 			编码
	 * @return
	 * 			响应结果
	 * @throws IOException
	 * 			IO异常
	 */
	public static String URLGet(String url, Map<String, String> params, String enc){

		String response = EMPTY;
		GetMethod getMethod = null;		
		StringBuffer strtTotalURL = new StringBuffer(EMPTY);
		
	    if(strtTotalURL.indexOf("?") == -1) {
	      strtTotalURL.append(url).append("?").append(getUrl(params, enc));
	    } else {
	    	strtTotalURL.append(url).append("&").append(getUrl(params, enc));
	    }
	    log.debug("GET请求URL = \n" + strtTotalURL.toString());
	    
		try {
			getMethod = new GetMethod(strtTotalURL.toString());
			getMethod.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=" + enc);
			//执行getMethod
			int statusCode = client.executeMethod(getMethod);
			if(statusCode == HttpStatus.SC_OK) {
				response = getMethod.getResponseBodyAsString();
			}else{
				log.debug("响应状态码 = " + getMethod.getStatusCode());
			}
		}catch(HttpException e){
			log.error("发生致命的异常，可能是协议不对或者返回的内容有问题", e);
			e.printStackTrace();
		}catch(IOException e){
			log.error("发生网络异常", e);
			e.printStackTrace();
		}finally{
			if(getMethod != null){
				getMethod.releaseConnection();
				getMethod = null;
			}
		}
		
		return response;
	}	

	/**
	 * 据Map生成URL字符串
	 * @param map
	 * 			Map
	 * @param valueEnc
	 * 			URL编码
	 * @return
	 * 			URL
	 */
	private static String getUrl(Map<String, String> map, String valueEnc) {
		
		if (null == map || map.keySet().size() == 0) {
			return (EMPTY);
		}
		StringBuffer url = new StringBuffer();
		Set<String> keys = map.keySet();
		for (Iterator<String> it = keys.iterator(); it.hasNext();) {
			String key = it.next();
			if (map.containsKey(key)) {
				String val = map.get(key);
				String str = val != null ? val : EMPTY;
				try {
					str = URLEncoder.encode(str, valueEnc);
				} catch (UnsupportedEncodingException e) {
					e.printStackTrace();
				}
				url.append(key).append("=").append(str).append(URL_PARAM_CONNECT_FLAG);
			}
		}
		String strURL = EMPTY;
		strURL = url.toString();
		if (URL_PARAM_CONNECT_FLAG.equals(EMPTY + strURL.charAt(strURL.length() - 1))) {
			strURL = strURL.substring(0, strURL.length() - 1);
		}
		
		return (strURL);
	}
}