Android使用Apache HttpClient發送GET、POST請求

簡單的網頁下載，HttpURLConnection能夠完成，可是涉及到用戶登陸等權限相關問題，就須要涉及Session、Cookies。，就很難使用HttpURLConnection來處理了。Apache開源組織提供了一個HttpClient項目能夠處理這些問題。HttpClient關注於如何發送請求、接受請求，以及管理HTTP連接。
使用HttpClient對象來發送請求、接受響應步驟：

1. 建立HttpClient對象

2. 若是要發送GET請求，建立HttpGet對象；若是是POST請求，則建立HttpPost對象。

3. 若是須要添加參數，對於HttpGet直接在構造URL的時候填入參數。對於POST請求，使用setEntity(HttpEntity entity)方法來設置

4. 調用HttpClient對象的execute（HttpUriRequest request）發送請求，此方法返回一個HttpResponse

5. 調用HttpResponse的getALLHeaders()、getHeaders(String name)等方法可獲取服務器響應頭；調用HttpResponse的getEntity（）方法可獲取HttpEntity對象，該對象包裝了服務器響應內容。

注意：

很多地方說能夠使用HttpGet和HttpPost共同的setParams(HttpParams params)方法添加請求參數，可是我沒有設置成功，網上搜索發現好多人也沒成功。Even Apache’s official example uses URIBuilder’s setParameter method to build the params out in the URI，因此沒有使用這種方法.

GET請求Demo：

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public class MainActivity extends Activity {        @Override      protected void onCreate(Bundle savedInstanceState) {          super .onCreate(savedInstanceState);          setContentView(R.layout.activity_main);          TextView textViewShow = (TextView) findViewById(R.id.showText);          //直接在URL後添加請求參數          String url = "http://192.168.1.103/index.php?get1=hello&get2=bay" ;          try {              // 建立DefaultHttpClient對象              HttpClient httpclient = new DefaultHttpClient();              // 建立一個HttpGet對象              HttpGet get = new HttpGet(url);              // 獲取HttpResponse對象              HttpResponse response = httpclient.execute(get);              //判斷是否連接成功              if (response.getStatusLine().getStatusCode() == 200 ) {                  //實體轉換爲字符串                  String content = EntityUtils.toString(response.getEntity());                  textViewShow.setText(content);              } else {                  textViewShow.setText( "網絡錯誤" );              }            } catch (ClientProtocolException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IOException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }      }        @Override      public boolean onCreateOptionsMenu(Menu menu) {          // Inflate the menu; this adds items to the action bar if it is present.          getMenuInflater().inflate(R.menu.main, menu);          return true ;      } }

POST請求Demo：

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public class MainActivity extends Activity {        @Override      protected void onCreate(Bundle savedInstanceState) {          super .onCreate(savedInstanceState);          setContentView(R.layout.activity_main);          TextView textViewShow = (TextView) findViewById(R.id.showText);            String url = "http://192.168.1.103/index.php" ;          HttpClient httpClient = new DefaultHttpClient();          try {          HttpPost post = new HttpPost(url);          List params = new ArrayList();          params.add( new BasicNameValuePair( "get1" , "hello" ));          params.add( new BasicNameValuePair( "get2" , "usrl" ));                post.setEntity( new UrlEncodedFormEntity(params, HTTP.UTF_8));              HttpResponse response = httpClient.execute(post);              if (response.getStatusLine().getStatusCode() == 200 ){                  String content = EntityUtils.toString(response.getEntity());                  textViewShow.setText(content);                } else {                  textViewShow.setText( "網絡問題" );              }            } catch (UnsupportedEncodingException e) {              // TODO Auto-generated catch block              textViewShow.setText( "UnsupportedEncodingException" );          } catch (ClientProtocolException e) {              // TODO Auto-generated catch block              textViewShow.setText( "ClientProtocolException" );          } catch (IOException e) {              // TODO Auto-generated catch block              textViewShow.setText( "IOException" );          }        }        @Override      public boolean onCreateOptionsMenu(Menu menu) {          // Inflate the menu; this adds items to the action bar if it is present.          getMenuInflater().inflate(R.menu.main, menu);          return true ;      }   }