Android 網絡數據的處理之 HttpClient
這一章我們主要來介紹網絡數據的傳遞與處理,相信很多讀者都希望做出來的應用能跟網絡上的數據進行互動,如微博,論壇之類的,這里我們就要學習網絡傳輸與返回數據的處理,首先網絡傳遞參數有POST跟GET兩種協議,做過網頁或是學習過的同學應該知道.網頁每個表單中都有一個<form action="XXX" method="post">參數,這里method就是提交表單參數使用的協議,當然,協議不止這兩種,還有文件上傳協議,這我們以后會講,今天我們首來就來熟悉Android中對于POST跟GET協議的應用,首先我們提供了一個HttpConnectionUtil.java的輔助類,這里面對POST跟GET進行了封裝
import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import java.util.ArrayList; import java.util.List; import java.util.Map;import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair;
import android.os.Handler; import android.util.Log;
public class HttpConnectionUtil { public static enum HttpMethod { GET, POST }
/** * 異步連接 * * @param url * 網址 * @param method * Http方法,POST跟GET * @param callback * 回調方法,返回給頁面或其他的數據 */ public void asyncConnect(final String url, final HttpMethod method, final HttpConnectionCallback callback) { asyncConnect(url, null, method, callback); } /** * 同步方法 * * @param url * 網址 * @param method * Http方法,POST跟GET * @param callback * 回調方法,返回給頁面或其他的數據 */ public void syncConnect(final String url, final HttpMethod method, final HttpConnectionCallback callback) { syncConnect(url, null, method, callback); } /** * 異步帶參數方法 * * @param url * 網址 * @param params * POST或GET要傳遞的參數 * @param method * 方法,POST或GET * @param callback * 回調方法 */ public void asyncConnect(final String url, final Map<String, String> params, final HttpMethod method, final HttpConnectionCallback callback) { Handler handler = new Handler(); Runnable runnable = new Runnable() { public void run() { syncConnect(url, params, method, callback); } }; handler.post(runnable); } /** * 同步帶參數方法 * * @param url * 網址 * @param params * POST或GET要傳遞的參數 * @param method * 方法,POST或GET * @param callback * 回調方法 */ public void syncConnect(final String url, final Map<String, String> params, final HttpMethod method, final HttpConnectionCallback callback) { String json = null; BufferedReader reader = null; try { HttpClient client = new DefaultHttpClient(); HttpUriRequest request = getRequest(url, params, method); HttpResponse response = client.execute(request); if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { reader = new BufferedReader(new InputStreamReader(response .getEntity().getContent())); StringBuilder sb = new StringBuilder(); for (String s = reader.readLine(); s != null; s = reader .readLine()) { sb.append(s); } json = sb.toString(); } } catch (ClientProtocolException e) { Log.e("HttpConnectionUtil", e.getMessage(), e); } catch (IOException e) { Log.e("HttpConnectionUtil", e.getMessage(), e); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { // ignore me } } callback.execute(json); } /** * POST跟GET傳遞參數不同,POST是隱式傳遞,GET是顯式傳遞 * * @param url * 網址 * @param params * 參數 * @param method * 方法 * @return */ private HttpUriRequest getRequest(String url, Map<String, String> params, HttpMethod method) { if (method.equals(HttpMethod.POST)) { List<NameValuePair> listParams = new ArrayList<NameValuePair>(); if (params != null) { for (String name : params.keySet()) { listParams.add(new BasicNameValuePair(name, params .get(name))); } } try { UrlEncodedFormEntity entity = new UrlEncodedFormEntity( listParams); HttpPost request = new HttpPost(url); request.setEntity(entity); return request; } catch (UnsupportedEncodingException e) { // Should not come here, ignore me. throw new java.lang.RuntimeException(e.getMessage(), e); } } else { if (url.indexOf("?") < 0) { url += "?"; } if (params != null) { for (String name : params.keySet()) { try { url += "&" + name + "=" + URLEncoder.encode(params.get(name), "UTF-8"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } } HttpGet request = new HttpGet(url); return request; } } /** * 回調接口 * @author Administrator * */ public interface HttpConnectionCallback { /** * Call back method will be execute after the http request return. * * @param response * the response of http request. The value will be null if * any error occur. */ void execute(String response); }}</pre>
這個類也是我從網上看到的,使用起來相當方便,希望讀者能學會怎樣使用,其實像java學習,可以將一些有用的類或是方法定義個自己包,將它們放進去,下次要用的話只要在主程序中調用就行了,這也是面向對象重要的方法.
這里面的方法,我就沒有一行一行定義說明了,里面用的都是HttpClient的中方法
接下來,我們用這個類來進行Android的應用
main.xml(模板文件)
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/http_edit" android:text="http://"> <requestFocus></requestFocus> </EditText> <RelativeLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/relativeLayout1"> <Button android:text="取消" android:layout_width="wrap_content" android:id="@+id/http_cancal" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_alignParentRight="true"></Button> <Button android:text="確定" android:layout_width="wrap_content" android:id="@+id/http_ok" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_toLeftOf="@+id/http_cancal" android:layout_marginRight="14dp"></Button> </RelativeLayout> <ScrollView android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:id="@+id/http_text" android:text="TextView" android:textAppearance="?android:attr/textAppearanceSmall" android:layout_height="match_parent" android:layout_width="match_parent"></TextView> </ScrollView> </LinearLayout>然后就是主Actitiv的java代碼了import android.app.Activity; import android.os.Bundle; import android.text.Html; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import com.kang.http.HttpConnectionUtil; import com.kang.http.HttpConnectionUtil.HttpConnectionCallback; import com.kang.http.HttpConnectionUtil.HttpMethod; public class HttpClientDemo extends Activity { private Button ok_btn; private Button cancal_btn; private EditText edit_text; private TextView text; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.http_client); //確定按鈕 ok_btn = (Button) findViewById(R.id.http_ok); ok_btn.setOnClickListener(new ClickEvent()); //取消按鈕 cancal_btn = (Button) findViewById(R.id.http_cancal); cancal_btn.setOnClickListener(new ClickEvent()); //文本編輯框 edit_text = (EditText) findViewById(R.id.http_edit); //文本框 text = (TextView) findViewById(R.id.http_text); } //自定義按鈕點擊方法 public class ClickEvent implements OnClickListener { @Override public void onClick(View v) { switch (v.getId()) { case R.id.http_ok: //網址 String url = edit_text.getText().toString().trim(); if (!url.equals("http://") && !url.equals("")) { //自定義類,封裝了GET/POST方法,而且同樣也封裝了同步跟異步的方法 HttpConnectionUtil conn = new HttpConnectionUtil(); conn.asyncConnect(url, HttpMethod.GET, new HttpConnectionCallback() { @Override public void execute(String response) { text.setText(Html.fromHtml(response)); } }); } break; case R.id.http_cancal: edit_text.setText("http://"); break; } } } }看里面 ClickEvent類中onClick方法中我們就使用了自定義的HttpConnectionUtil類,別急著運行了,接下來還有一步,也是最重要的,就是權限的增加,你要訪問網絡,肯定需要訪問網絡的權限,在AndroidManifest.xml中加入<uses- permission android:name="android.permission.INTERNET"></uses-permission>這一句,至于加哪里,那你可別問我了,百度或是google一下吧,呵呵,賣賣關子,現在就可以運行了,看圖是不是跟我的一樣
你一定會奇怪,怎么會有其他一些代碼呢?呵呵,這里我們取出的是它的源代碼.OK,這一章講完了
本文由用戶 openkk 自行上傳分享，僅供網友學習交流。所有權歸原作者，若您的權利被侵害，請聯系管理員。
轉載本站原創文章，請注明出處，并保留原始鏈接、圖片水印。
本站是一個以用戶分享為主的開源技術平臺，歡迎各類分享！