Android使用HTTP協議訪問網路——HttpClient

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套路篇

1.HttpClient是一個介面，因此無法建立它的執行個體，通常情況下都會建立一個DefaultHttpClient的執行個體

HttpClient httpClient=new DefaultHttpClient();

2.如果想要發起一條GET請求，就建立一個HttpGet對象，並傳入目標網路的對象，然後調用HtttpClient中的excute()方法：

HttpGet httpGet=new HttpGet("http://www.baidu.com");HttpResponse httpResponse=httpClient.execute(httpGet);

如果想發起一條POST請求會比GET複雜一點，首先建立一個HttpPost對象，並傳入目標網址

HttpPost httpPost=new HttpPost("http/:www.baidu.com");

然後通過NameValuePair集合來存放待提交的資料，並將這個參數傳入到一個UrlEncodedFormEntity中，然後調用HttpPost的setEntity（）方法將構建好的UrlEncodedFormEntity傳入

List<NameValuePair> params=new ArrayList<NameValuePair>();params.add(new BasicNameValuePair("username","admin"));params.add(new BasicNameValuepair("password","123456"));UrlEncodeFormEntity entity=new UrlEncodeFormEntity(params,"utf-8");httpPost.setEntity(entity);

接下來就和GET方法一樣啦，httpClient.execute(httpPost);

3.執行完execute()方法後會返回一個HttpResponse對象，伺服器返回的資料都在裡面，通常我們會先取出伺服器返回的狀態代碼，如果等於200，則說明請求響應成功

if(httpResponse.getStatusLine().getStatueCode()==200){　　//請求和響應都成功了}

4.讀取伺服器返回的具體內容，可以調用getEntity()訪問擷取到一個HttpEntity執行個體，然後調用EntityUtils.toString()這個靜態類將HttpEntity轉換成字串

HttpEntity entity=httpResponse.getEntity();

String response=EntityUtils.toString(entity);

如果返回的資料帶有中文，轉換的時候需要將字元集指定為utf-8

String response=EntityUtils.toString(entity,"utf-8");

實戰篇

MainActivity

import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpGet;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.util.EntityUtils;public class MainActivity extends AppCompatActivity implements View.OnClickListener{    public static final int SHOW_RESPONSE=0;//用於更新操作    private Button sendRequest_Button;    private TextView responseText;    //用於處理和發送訊息的Handler    private Handler handler=new Handler(){        public void handleMessage(Message msg){            switch (msg.what){                case SHOW_RESPONSE:                    String response=(String)msg.obj;                    responseText.setText(response);            }        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        sendRequest_Button=(Button)findViewById(R.id.sendrequest);        responseText=(TextView)findViewById(R.id.response_text);        sendRequest_Button.setOnClickListener(this);    }    @Override    public void onClick(View v) {        if(v.getId()==R.id.sendrequest){            sendRequestWithHttpClient();        }    }    public void sendRequestWithHttpClient(){        new Thread(new Runnable() {            @Override            public void run() {                try{                    HttpClient httpClient=new DefaultHttpClient();                    HttpGet httpGet=new HttpGet("http://www.baidu.com");                    HttpResponse httpResponse=httpClient.execute(httpGet);                    if(httpResponse.getStatusLine().getStatusCode()==200){                        //請求和響應都成功了                        HttpEntity entity=httpResponse.getEntity();                        String response= EntityUtils.toString(entity, "utf-8");                        Message message=new Message();                        message.what=SHOW_RESPONSE;                        //將伺服器返回的結果儲存到Message中                        message.obj=response.toString();                        handler.sendMessage(message);                    }                }catch(Exception e){                }finally {                }            }        }).start();    }}

AndroidManifest

<uses-permission android:name="android.permission.INTERNET"></uses-permission>

Layout

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <Button        android:id="@+id/sendrequest"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="Send Request"/>    <ScrollView        android:layout_width="wrap_content"        android:layout_height="wrap_content">        <TextView            android:id="@+id/response_text"            android:layout_width="match_parent"            android:layout_height="wrap_content" />    </ScrollView></LinearLayout>

 

Android使用HTTP協議訪問網路——HttpClient