HttpClient的使用，整理了一个工具类

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import javax.servlet.http.HttpServletRequest;

import org.apache.http.HttpEntity;

import org.apache.http.HttpResponse;

import org.apache.http.NameValuePair;

import org.apache.http.client.config.RequestConfig;

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.impl.client.CloseableHttpClient;

import org.apache.http.impl.client.HttpClientBuilder;

import org.apache.http.message.BasicNameValuePair;

import org.apache.http.util.EntityUtils;

/**

 * http请求工具类、获取用户端ip工具类

 * @author liao.h

 *

 */

public class HttpUtil {

    /**

     * 发送一个post请求

     * @param url

     *            请求路径

     * @param parmsMap

     *            发送请求的参数

     * @return 请求结果

     */

    public static String doPost(String url, Map<String, String> parmsMap) {

        // 创建HttpClientBuilder

        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();

        // HttpClient

        CloseableHttpClient closeableHttpClient = httpClientBuilder.build();

        // 配置请求的超时设置

        RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(5000).setConnectTimeout(5000).setSocketTimeout(5000).build();

        HttpPost httpPost = new HttpPost(url);

        httpPost.setHeader("Content-Type", "application/json;charset=utf-8");

        httpPost.setConfig(requestConfig);

        // 创建参数队列

        List<NameValuePair> formparams = new ArrayList<NameValuePair>();

        for (Entry<String, String> entry : parmsMap.entrySet()) {

            formparams.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));

        }

        UrlEncodedFormEntity entity;

        try {

            entity = new UrlEncodedFormEntity(formparams, "UTF-8");

            // 创建带字符创参数和字符编码的

            httpPost.setEntity(entity);

            HttpResponse httpResponse;

            // post请求

            httpResponse = closeableHttpClient.execute(httpPost);

            // getEntity()

            HttpEntity httpEntity = httpResponse.getEntity();

            if (httpEntity != null) {

                // 打印响应内容

                return EntityUtils.toString(httpEntity, "UTF-8");

            }

            // 释放资源

            closeableHttpClient.close();

        }

        catch (Exception e) {

            e.printStackTrace();

        }

        return null;

    }

    /**

     * 发送一个get请求

     * 

     * @param url

     *            请求路径

     * @return 请求结果

     */

    public static String doGet(String url) {

        // 创建HttpClientBuilder

        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();

        // HttpClient

        CloseableHttpClient closeableHttpClient = httpClientBuilder.build();

        HttpGet httpGet = new HttpGet(url);

        httpGet.setHeader("Content-Type", "application/json;charset=utf-8");

        try {

            // 执行get请求

            HttpResponse httpResponse = closeableHttpClient.execute(httpGet);

            // 获取响应消息实体

            HttpEntity entity = httpResponse.getEntity();

            // 判断响应实体是否为空

            if (entity != null) {

                String a = EntityUtils.toString(entity);

                return a;

            }

            else {

                return httpResponse.getStatusLine().getStatusCode() + "";

            }

        }

        catch (IOException e) {

            e.printStackTrace();

        }

        finally {

            try { // 关闭流并释放资源

                closeableHttpClient.close();

            }

            catch (IOException e) {

                e.printStackTrace();

            }

        }

        return null;

    }

    /**

     * 获取客户端ip地址

     * @param request

     * @return ip地址

     */

    public static String getIpAddr(HttpServletRequest request) {

        String ip = request.getHeader("x-forwarded-for");

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {

            ip = request.getHeader("Proxy-Client-IP");

        }

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {

            ip = request.getHeader("WL-Proxy-Client-IP");

        }

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {

            ip = request.getHeader("HTTP_CLIENT_IP");

        }

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {

            ip = request.getHeader("HTTP_X_FORWARDED_FOR");

        }

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {

            ip = request.getRemoteAddr();

        }

        return ip;

    }

    
}

HttpClient4.0下载地址
http://download.csdn.net/detail/liaohao6/9549724