Get请求和Post请求的区别

首先我们先了解下Get请求和Post请求的区别：

表单提交中get和 post方式的区别有5点：
1.get是从服务器上获取数据，post是向服务器传送数据。
2.get是把参数数据队列加到提交表单的 ACTION属性所指的URL中，值和表单内各个字段一一对应，在URL中可以看到。post是通过HTTPpost机制，将表单内各个字段与其内容放置在HTML HEADER内一起传送到ACTION属性所指的URL地址。用户看不到这个过程。
3.对于get方式，服务器端用 Request.QueryString获取变量的值，对于post方式，服务器端用Request.Form获取提交的数据。
4.get 传送的数据量较小，不能大于2KB。post传送的数据量较大，一般被默认为不受限制。但理论上，IIS4中最大量为80KB，IIS5中为100KB。
5.get安全性非常低，post安全性较高。

一、HttpClient方式

1、HTTP GET 示例:

 public class TestHttpGetMethod{  
      public void get(){  
         BufferedReader in = null;  
         try{  
              HttpClient client = new DefaultHttpClient();  
              HttpGet request = new HttpGet();  
              request.setURI("http://w26.javaeye.com");  
              HttpResponse response = client.execute(request);   
              in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));     
             StringBuffer sb = new StringBuffer("");   
             String line = "";  
            String NL = System.getProperty("line.separator");  
             while((line = in.readLine()) != null){  
                 sb.append(line + NL); 
 
             }  
             in.close();  
            String page = sb.toString();  
             Log.i(TAG, page);  
         }catch(Exception e){  
             Log.e(TAG,e.toString())  
         }finally{  
             if(in != null){  
                 try{  
                     in.close();  
                 }catch(IOException ioe){  
                    Log.e(TAG, ioe.toString());  
                 }  
             }  
         }  
     }  
 }

带参数的 HTTP GET: 
HttpGet request = new HttpGet("http://www.baidu.com/s?wd=amos_tl");  
client.execute(request);

2、HTTP POST 示例:

 public class TestHttpPostMethod{  
     public void post(){  
         BufferedReader in = null;  
         try{  
             HttpClient client = new DefaultHttpClient();  
             HttpPost request = new HttpPost("http://localhost/upload.jsp");   
             List<NameValuePair> postParams = new ArrayList<NameValuePair>();  
              postParams.add(new BasicNameValuePair("filename", "sex.mov"));  
             UrlEncodeFormEntity formEntity = new UrlEncodeFormEntity(postParams);  
             request.setEntity(formEntity);  
             HttpResponse response = client.execute(request);  
            in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));     
             StringBuffer sb = new StringBuffer("");   
             String line = "";  
            String NL = System.getProperty("line.separator");  
             while((line = in.readLine()) != null){  
                sb.append(line + NL);  
             }  
             in.close();  
             String result = sb.toString();  
            Log.i(TAG, result );  
         }catch(Exception e){  
            Log.e(TAG,e.toString())  
         }finally{  
             if(in != null){  
                try{  
                     in.close();  
                 }catch(IOException ioe){  
                     Log.e(TAG, ioe.toString());  
                 }  
             }  
         }  
     } 
 }

二、HttpURLConnection 方式

  URL url = null;
  HttpURLConnection conn = null;
  InputStream in = null;
  OutputStream out = null;
  byte[] data ="测试字符串".getBytes();
  try{
     url =new URL("www.xxx.com/servlet");
   conn = (HttpURLConnection) url.openConnection();
 
    //设置连接属性
    conn.setDoOutput(true);// 使用 URL 连接进行输出
    conn.setDoInput(true);// 使用 URL 连接进行输入
    conn.setUseCaches(false);// 忽略缓存
    conn.setConnectTimeout(30000);//设置连接超时时长，单位毫秒
    conn.setRequestMethod("POST");//设置请求方式，POST or GET，注意：如果请求地址为一个servlet地址的话必须设置成POST方式
 
 //设置请求头
   conn.setRequestProperty("Accept", "*/*");
   conn.setRequestProperty("Connection", "Keep-Alive");
   conn.setRequestProperty("Accept-Charset", "utf-8");
   if (data != null) {
      out = conn.getOutputStream();
      out.write(data);
   }
   int code = conn.getResponseCode();
   if(code ==200){
     in = conn.getInputStream();// 可能造成阻塞
      long len = conn.getContentLength();
      byte[] bs = new byte[(int) len];//返回结果字节数组
     int all = 0;
   int dn = 0;
      while ((dn = in.read(bs, all, 1)) > 0) {
        all += dn;
        if (all == len) {
        break;
        }
      }
   }
 }














那么接下来让我们看看在Android平台开发中如何执行一个Post请求：

以下是代码示例：


 package com.jindegege.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) {
                 }
         }
 }