Android[中級教程]第九章 網絡數據的處理之HttpClient – Android移動開發技術文章_手機開發 Android移動開發教學課程

 

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,這裡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,這裡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,這我們以後會講,今天我們首來就來熟悉Android中對於POST跟GET協議的應用,首先我們提供瞭一個HttpConnectionUtil.java的輔助類,這裡面對POST跟GET進行瞭封裝

 

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); 

    } 

 

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,下次要用的話隻要在主程序中調用就行瞭,這也是面向對象重要的方法.

 

這裡面的方法,我就沒有一行一行定義說明瞭,裡面用的都是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> 

然後就是主Actitiv的java代碼瞭

 

 

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,封裝瞭GET/POST方法,而且同樣也封裝瞭同步跟異步的方法 

                    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; 

 

            } 

 

        } 

 

    } 

看裡面ClickEvent類中onClick方法中我們就使用瞭自定義的HttpConnectionUtil類,別急著運行瞭,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,至於加哪裡,那你可別問我瞭,百度或是google一下吧,呵呵,賣賣關子,現在就可以運行瞭,看圖是不是跟我的一樣

你一定會奇怪,怎麼會有其他一些代碼呢?呵呵,這裡我們取出的是它的源代碼.OK,這一章講完瞭,下一章我們就要來實現Mysql數據庫+PHP+Android的顯示瞭,相信這會是很多讀者感興趣的一章,謝謝

 

摘自:kangkangz4的專欄

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