HTTP：  超文本传送协议（hypertext transport protocol），用于传送WWW方式的数据。属于应用层的面向对象的协议。HTTP采用了请求/响应模型。客户端向服务器发送的请求包含了：请求的方法、URL、协议版本、请求修饰符、客户信息和内容的消息结构。服务器端以一个状态行作为响应，响应的内容包括消息协议的版本、成功或者错误编码、服务器信息、实体元信息以及可能的实体内容。Http定义了与服务器交互的不同方法，最基本的4种分别是GET，POST，PUT，DELETE。URL全称是资源描述符，我们可以认为：一个URL地址用于描述一个网络上的资源，而HTTP中的GET， POST，PUT，DELETE就对应着对这个资源的查，改，增，删4个操作。GET一般用于获取/查询资源信息，而POST一般用于更新资源信息。Http通信中用的最多的就是Get和Post。Get请求可以获取静态页面，也可以把参数放在URL字串后面，传递给服务器。Post与Get的不同之处在于Post的参数不是放在http请求数据中。

例如：--1--HttpURLConnection默认使用GET方式
URL url = new URL("http://www.google.cn/"); 
//使用HttpURLConnection打开连接 
HttpURLConnection urlConn = (HttpURLConnection) url.openConnection(); 
//得到读取的内容(流) 
InputStreamReader in = new InputStreamReader(urlConn.getInputStream()); 
// 为输出创建BufferedReader 
BufferedReader buffer = new BufferedReader(in); 
String inputLine = null; 
//使用循环来读取获得的数据 
while (((inputLine = buffer.readLine()) != null)) 
{ 
//我们在每一行后面加上一个"\n"来换行 
resultData += inputLine + "\n"; 
} 
//关闭InputStreamReader 
in.close(); 
//关闭http连接 
urlConn.disconnect();

String httpUrl = "http://192.168.1.110:8080/httpget.jsp"; 
//HttpPost连接对象 
HttpPost httpRequest = new HttpPost(httpUrl); 
//使用NameValuePair来保存要传递的Post参数 
List<NameValuePair> params = new ArrayList<NameValuePair>(); 
//添加要传递的参数 
params.add(new BasicNameValuePair("par", "HttpClient_android_Post")); 
//设置字符集 
HttpEntity httpentity = new UrlEncodedFormEntity(params, "gb2312"); 
//请求httpRequest 
httpRequest.setEntity(httpentity); 
//取得默认的HttpClient 
HttpClient httpclient = new DefaultHttpClient(); 
//取得HttpResponse 
HttpResponse httpResponse = httpclient.execute(httpRequest); 
//HttpStatus.SC_OK表示连接成功 
if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) 
{ 
//取得返回的字符串 
String strResult = EntityUtils.toString(httpResponse.getEntity()); 
mTextView.setText(strResult); 
} 
else
{ 
mTextView.setText("请求错误!"); 
} 
}

package com.jixuzou.search;
 import java.util.ArrayList;
 import java.util.List;
 import org.apache.http.HttpResponse;
 import org.apache.http.NameValuePair;
 import org.apache.http.client.entity.UrlEncodedFormEntity;
 import org.apache.http.client.methods.HttpPost;
 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 android.app.Activity;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 public class mian extends Activity {
         /** Called when the activity is first created. */
         private Button btnTest;
         @Override
         public void onCreate(Bundle savedInstanceState) {
                 super.onCreate(savedInstanceState);
                 setContentView(R.layout.main);
                 btnTest = (Button) findViewById(R.id.Button01);
                 btnTest.setOnClickListener(new OnClickListener() {
                         @Override
                         public void onClick(View v) {
                                 getWeather();
                         }
                 });
         }
         private void getWeather(){
                 try {
                         final String SERVER_URL = "http://webservice.webxml.com.cn/WebServices/WeatherWS.asmx/getWeather"; // 定义需要获取的内容来源地址
                         HttpPost request = new HttpPost(SERVER_URL); // 根据内容来源地址创建一个Http请求
                         List params = new ArrayList();
                         params.add(new BasicNameValuePair("theCityCode", "长沙")); // 添加必须的参数
                         params.add(new BasicNameValuePair("theUserID", "")); // 添加必须的参数
                         request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8)); // 设置参数的编码
                         HttpResponse httpResponse = new DefaultHttpClient().execute(request); // 发送请求并获取反馈
 // 解析返回的内容
                         if (httpResponse.getStatusLine().getStatusCode() != 404)
                         {
                                 String result = EntityUtils.toString(httpResponse.getEntity());
                                 System.out.println(result);
                         }
                 } catch (Exception e) {
                 }
         }
 }