Android 網絡操作常用的兩個類

 Android SDK集成了Apache HttpClient模塊。要注意的是，這裡的Apache HttpClient模塊是HttpClient 4.0（org.apache.http.*），而不是常見的 Jakarta Commons HttpClient 3.x（org.apache.commons.httpclient.*）。

           HttpClient常用HttpGet和HttpPost這兩個類，分別對應Get方式和Post方式。

           無論是使用HttpGet，還是使用HttpPost，都必須通過如下3步來訪問HTTP資源。
         
            1.創建HttpGet或HttpPost對象，將要請求的URL通過構造方法傳入HttpGet或HttpPost對象。

           2.使用DefaultHttpClient類的execute方法發送HTTP GET或HTTP POST請求，並返回HttpResponse對象。

           3.通過HttpResponse接口的getEntity方法返回響應信息，並進行相應的處理。

           如果使用HttpPost方法提交HTTP POST請求，則需要使用HttpPost類的setEntity方法設置請求參數。參數則必須用NameValuePair[]數組存儲。

下面給出一些實例：

 
Get方式：

[java]  // HttpGet方式請求    
public static void requestByHttpGet() throws Exception {   
    String path = "https://reg.163.com/logins.jsp?id=helloworld&pwd=android";   
    // 新建HttpGet對象    
    HttpGet httpGet = new HttpGet(path);   
    // 獲取HttpClient對象    
    HttpClient httpClient = new DefaultHttpClient();   
    // 獲取HttpResponse實例    
    HttpResponse httpResp = httpClient.execute(httpGet);   
    // 判斷是夠請求成功    
    if (httpResp.getStatusLine().getStatusCode() == HTTP_200) {   
        // 獲取返回的數據    
        String result = EntityUtils.toString(httpResp.getEntity(), "UTF-8");   
        Log.i(TAG_HTTPGET, "HttpGet方式請求成功，返回數據如下：");   
        Log.i(TAG_HTTPGET, result);   
    } else {   
        Log.i(TAG_HTTPGET, "HttpGet方式請求失敗");   
    }   
}   

// HttpGet方式請求 
public static void requestByHttpGet() throws Exception { 
    String path = "https://reg.163.com/logins.jsp?id=helloworld&pwd=android"; 
    // 新建HttpGet對象 
    HttpGet httpGet = new HttpGet(path); 
    // 獲取HttpClient對象 
    HttpClient httpClient = new DefaultHttpClient(); 
    // 獲取HttpResponse實例 
    HttpResponse httpResp = httpClient.execute(httpGet); 
    // 判斷是夠請求成功 
    if (httpResp.getStatusLine().getStatusCode() == HTTP_200) { 
        // 獲取返回的數據 
        String result = EntityUtils.toString(httpResp.getEntity(), "UTF-8"); 
        Log.i(TAG_HTTPGET, "HttpGet方式請求成功，返回數據如下："); 
        Log.i(TAG_HTTPGET, result); 
    } else { 
        Log.i(TAG_HTTPGET, "HttpGet方式請求失敗"); 
    } 
} 
[java]  public String doGet()   
    {   
        String uriAPI = "http://XXXXX?str=I+am+get+String";   
        String result= "";   
//      HttpGet httpRequst = new HttpGet(URI uri);    
//      HttpGet httpRequst = new HttpGet(String uri);    
//      創建HttpGet或HttpPost對象，將要請求的URL通過構造方法傳入HttpGet或HttpPost對象。    
        HttpGet httpRequst = new HttpGet(uriAPI);   
   
//      new DefaultHttpClient().execute(HttpUriRequst requst);    
        try {   
   //使用DefaultHttpClient類的execute方法發送HTTP GET請求，並返回HttpResponse對象。    
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequst);//其中HttpGet是HttpUriRequst的子類    
            if(httpResponse.getStatusLine().getStatusCode() == 200)   
            {   
                HttpEntity httpEntity = httpResponse.getEntity();   
                result = EntityUtils.toString(httpEntity);//取出應答字符串    
            // 一般來說都要刪除多余的字符     
                result.replaceAll("\r", "");//去掉返回結果中的"\r"字符，否則會在結果字符串後面顯示一個小方格      
            }   
                   else    
                        httpRequst.abort();   
           } catch (ClientProtocolException e) {   
            // TODO Auto-generated catch block    
            e.printStackTrace();   
            result = e.getMessage().toString();   
        } catch (IOException e) {   
            // TODO Auto-generated catch block    
            e.printStackTrace();   
            result = e.getMessage().toString();   
        }   
        return result;   
    }   

public String doGet() 
    { 
        String uriAPI = "http://XXXXX?str=I+am+get+String"; 
        String result= ""; 
//      HttpGet httpRequst = new HttpGet(URI uri); 
//      HttpGet httpRequst = new HttpGet(String uri); 
//      創建HttpGet或HttpPost對象，將要請求的URL通過構造方法傳入HttpGet或HttpPost對象。 
        HttpGet httpRequst = new HttpGet(uriAPI); 
 
//      new DefaultHttpClient().execute(HttpUriRequst requst); 
        try { 
   //使用DefaultHttpClient類的execute方法發送HTTP GET請求，並返回HttpResponse對象。 
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequst);//其中HttpGet是HttpUriRequst的子類 
            if(httpResponse.getStatusLine().getStatusCode() == 200) 
            { 
                HttpEntity httpEntity = httpResponse.getEntity(); 
                result = EntityUtils.toString(httpEntity);//取出應答字符串 
            // 一般來說都要刪除多余的字符  
                result.replaceAll("\r", "");//去掉返回結果中的"\r"字符，否則會在結果字符串後面顯示一個小方格   
            } 
                   else  
                        httpRequst.abort(); 
           } catch (ClientProtocolException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
            result = e.getMessage().toString(); 
        } catch (IOException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
            result = e.getMessage().toString(); 
        } 
        return result; 
    } 
Post方式：

如果使用HttpPost方法提交HTTP POST請求，則需要使用HttpPost類的setEntity方法設置請求參數。參數則必須用NameValuePair[]數組存儲。

[java]  <STRONG>public String doPost()   
    {   
        String uriAPI = "http://XXXXXX";//Post方式沒有參數在這裡   
        String result = "";   
        HttpPost httpRequst = new HttpPost(uriAPI);//創建HttpPost對象    
           
        List <NameValuePair> params = new ArrayList<NameValuePair>();   
        params.add(new BasicNameValuePair("str", "I am Post String"));   
           
        try {   
            httpRequst.setEntity(new UrlEncodedFormEntity(params,HTTP.UTF_8));   
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequst);   
            if(httpResponse.getStatusLine().getStatusCode() == 200)   
            {   
                HttpEntity httpEntity = httpResponse.getEntity();   
                result = EntityUtils.toString(httpEntity);//取出應答字符串    
            }   
        } catch (UnsupportedEncodingException e) {   
            // TODO Auto-generated catch block    
            e.printStackTrace();   
            result = e.getMessage().toString();   
        }   
        catch (ClientProtocolException e) {   
            // TODO Auto-generated catch block    
            e.printStackTrace();   
            result = e.getMessage().toString();   
        }   
        catch (IOException e) {   
            // TODO Auto-generated catch block    
            e.printStackTrace();   
            result = e.getMessage().toString();   
        }   
        return result;   
    }  </STRONG> 

public String doPost() 
    { 
        String uriAPI = "http://XXXXXX";//Post方式沒有參數在這裡 
        String result = ""; 
        HttpPost httpRequst = new HttpPost(uriAPI);//創建HttpPost對象 
         
        List <NameValuePair> params = new ArrayList<NameValuePair>(); 
        params.add(new BasicNameValuePair("str", "I am Post String")); 
         
        try { 
            httpRequst.setEntity(new UrlEncodedFormEntity(params,HTTP.UTF_8)); 
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequst); 
            if(httpResponse.getStatusLine().getStatusCode() == 200) 
            { 
                HttpEntity httpEntity = httpResponse.getEntity(); 
                result = EntityUtils.toString(httpEntity);//取出應答字符串 
            } 
        } catch (UnsupportedEncodingException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
            result = e.getMessage().toString(); 
        } 
        catch (ClientProtocolException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
            result = e.getMessage().toString(); 
        } 
        catch (IOException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
            result = e.getMessage().toString(); 
        } 
        return result; 
    } 
[java]   <STRONG>// HttpPost方式請求    
public static void requestByHttpPost() throws Exception {   
    String path = "https://reg.163.com/logins.jsp";   
    // 新建HttpPost對象    
    HttpPost httpPost = new HttpPost(path);   
    // Post參數    
    List<NameValuePair> params = new ArrayList<NameValuePair>();   
    params.add(new BasicNameValuePair("id", "helloworld"));   
    params.add(new BasicNameValuePair("pwd", "android"));   
    // 設置字符集    
    HttpEntity entity = new UrlEncodedFormEntity(params, HTTP.UTF_8);   
    // 設置參數實體    
    httpPost.setEntity(entity);   
    // 獲取HttpClient對象    
    HttpClient httpClient = new DefaultHttpClient();   
    // 獲取HttpResponse實例    
    HttpResponse httpResp = httpClient.execute(httpPost);   
    // 判斷是夠請求成功    
    if (httpResp.getStatusLine().getStatusCode() == HTTP_200) {   
        // 獲取返回的數據    
        String result = EntityUtils.toString(httpResp.getEntity(), "UTF-8");   
        Log.i(TAG_HTTPGET, "HttpPost方式請求成功，返回數據如下：");   
        Log.i(TAG_HTTPGET, result);   
    } else {   
        Log.i(TAG_HTTPGET, "HttpPost方式請求失敗");   
    }   
}  </STRONG>