Android使用Apache HttpClient发送GET、POST请求

简单的网页下载，HttpURLConnection能够完成，可是涉及到用户登陆等权限相关问题，就须要涉及Session、Cookies。，就很难使用HttpURLConnection来处理了。Apache开源组织提供了一个HttpClient项目能够处理这些问题。HttpClient关注于如何发送请求、接受请求，以及管理HTTP连接。
使用HttpClient对象来发送请求、接受响应步骤：

1. 建立HttpClient对象

2. 若是要发送GET请求，建立HttpGet对象；若是是POST请求，则建立HttpPost对象。

3. 若是须要添加参数，对于HttpGet直接在构造URL的时候填入参数。对于POST请求，使用setEntity(HttpEntity entity)方法来设置

4. 调用HttpClient对象的execute（HttpUriRequest request）发送请求，此方法返回一个HttpResponse

5. 调用HttpResponse的getALLHeaders()、getHeaders(String name)等方法可获取服务器响应头；调用HttpResponse的getEntity（）方法可获取HttpEntity对象，该对象包装了服务器响应内容。

注意：

很多地方说能够使用HttpGet和HttpPost共同的setParams(HttpParams params)方法添加请求参数，可是我没有设置成功，网上搜索发现好多人也没成功。Even Apache’s official example uses URIBuilder’s setParameter method to build the params out in the URI，因此没有使用这种方法.

GET请求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后添加请求参数          String url = "http://192.168.1.103/index.php?get1=hello&get2=bay" ;          try {              // 建立DefaultHttpClient对象              HttpClient httpclient = new DefaultHttpClient();              // 建立一个HttpGet对象              HttpGet get = new HttpGet(url);              // 获取HttpResponse对象              HttpResponse response = httpclient.execute(get);              //判断是否连接成功              if (response.getStatusLine().getStatusCode() == 200 ) {                  //实体转换为字符串                  String content = EntityUtils.toString(response.getEntity());                  textViewShow.setText(content);              } else {                  textViewShow.setText( "网络错误" );              }            } 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请求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( "网络问题" );              }            } 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 ;      }   }