HttpClient 是apache 组织下面的一个用于处理HTTP 请求和响应的开源工具。所用jar包为httpclient-4.3.6.jar、httpcore-4.3.3.jar、httpmime-4.3.6.jar、commons-codec-1.6.jar。
发送Get请求代码如下：

package com.zkn.newlearn.httpclient;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;

import org.apache.http.Consts;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import com.google.common.collect.Lists;

public class HttpClientTest02 {

    public static void main(String[] args) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        InputStream is = null;
        String url = "http://localhost:8080/MyWebxTest/getCityByProvinceEname.do";
        //封装请求参数
        List<NameValuePair> params = Lists.newArrayList();
        params.add(new BasicNameValuePair("cityEname", "henan"));
        String str = "";
        try {
            //转换为键值对
            str = EntityUtils.toString(new UrlEncodedFormEntity(params, Consts.UTF_8));
            System.out.println(str);
            //创建Get请求
            HttpGet httpGet = new HttpGet(url+"?"+str);
            //执行Get请求，
            response = httpClient.execute(httpGet);
            //得到响应体
            HttpEntity entity = response.getEntity();
            if(entity != null){
                is = entity.getContent();
                //转换为字节输入流
                BufferedReader br = new BufferedReader(new InputStreamReader(is, Consts.UTF_8));
                String body = null;
                while((body=br.readLine()) != null){
                    System.out.println(body);
                }
            }
        } catch (ParseException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally{
            //关闭输入流，释放资源
            if(is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            //消耗实体内容
            if(response != null){
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            //关闭相应 丢弃http连接
            if(httpClient != null){
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        
    }
}