Android使用Apache HttpClient發送GET、POST請求

簡單的網頁下載，HttpURLConnection可以完成，但是涉及到使用者登入等許可權相關問題，就需要涉及Session、Cookies。，就很難使用HttpURLConnection來處理了。Apache開源組織提供了一個HttpClient項目可以處理這些問題。HttpClient關注於如何發送請求、接受請求，以及管理HTTP連結。
使用HttpClient對象來發送請求、接受響應步驟：


建立HttpClient對象
如果要發送GET請求，建立HttpGet對象；如果是POST請求，則建立HttpPost對象。
如果需要添加參數，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)方法來設定
調用HttpClient對象的execute（HttpUriRequest request）發送請求，此方法返回一個HttpResponse
調用HttpResponse的getALLHeaders()、getHeaders(String name)等方法可擷取伺服器回應標頭；調用HttpResponse的getEntity（）方法可擷取HttpEntity對象，該對象封裝了伺服器響應內容。
注意：


不少地方說可以使用HttpGet和HttpPost共同的setParams(HttpParams params)方法添加請求參數，但是我沒有設定成功，網上搜尋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，所以沒有使用這種方法.

GET請求Demo：

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);            // 擷取HttpResponse對象            HttpResponse response = httpclient.execute(get);            //判斷是否連結成功            if (response.getStatusLine().getStatusCode() == 200) {                //實體轉換為字串                String content = EntityUtils.toString(response.getEntity(),"utf-8");                textViewShow.setText(content);            }else{                textViewShow.setText("網路錯誤");            }         } 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：

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(),"utf-8");                textViewShow.setText(content);             }else{                textViewShow.setText("網路問題");            }         } 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;    } }