Android系列之网络（一）----使用HttpClient发送HTTP请求

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send Request" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <TextView
            android:id="@+id/TextView1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/hello_world" />
    </ScrollView>

</LinearLayout>

 1 package com.example.m04_http01;
 2 
 3 import org.apache.http.HttpEntity;
 4 import org.apache.http.HttpResponse;
 5 import org.apache.http.client.HttpClient;
 6 import org.apache.http.client.methods.HttpGet;
 7 import org.apache.http.impl.client.DefaultHttpClient;
 8 import org.apache.http.util.EntityUtils;
 9 import android.app.Activity;
10 import android.os.Bundle;
11 import android.os.Handler;
12 import android.os.Message;
13 import android.view.View;
14 import android.view.View.OnClickListener;
15 import android.widget.Button;
16 import android.widget.TextView;
17 
18 public class MainActivity extends Activity {
19 
20     public static final int SHOW_RESPONSE = 0;
21     
22     private Button button_sendRequest;
23     private TextView textView_response;
24     
25     //新建Handler的对象，在这里接收Message，然后更新TextView控件的内容
26     private Handler handler = new Handler() {
27 
28         @Override
29         public void handleMessage(Message msg) {
30             super.handleMessage(msg);
31             switch (msg.what) {
32             case SHOW_RESPONSE:
33                 String response = (String) msg.obj;
34                 textView_response.setText(response);
35                 break;
36 
37             default:
38                 break;
39             }            
40         }
41 
42     };
43     
44     @Override
45     protected void onCreate(Bundle savedInstanceState) {
46         super.onCreate(savedInstanceState);
47         setContentView(R.layout.activity_main);
48         textView_response = (TextView)findViewById(R.id.TextView1);
49         button_sendRequest = (Button)findViewById(R.id.button1);
50         
51         button_sendRequest.setOnClickListener(new OnClickListener() {
52             
53             //点击按钮时，执行sendRequestWithHttpClient()方法里面的线程
54             @Override
55             public void onClick(View v) {
56                 // TODO Auto-generated method stub
57                 sendRequestWithHttpClient();
58             }
59         });
60     }
61 
62     //方法：发送网络请求，获取百度首页的数据。在里面开启线程
63     private void sendRequestWithHttpClient() {
64         new Thread(new Runnable() {
65             
66             @Override
67             public void run() {
68                 //用HttpClient发送请求，分为五步
69                 //第一步：创建HttpClient对象
70                 HttpClient httpCient = new DefaultHttpClient();
71                 //第二步：创建代表请求的对象,参数是访问的服务器地址
72                 HttpGet httpGet = new HttpGet("http://www.baidu.com");
73                 
74                 try {
75                     //第三步：执行请求，获取服务器发还的相应对象
76                     HttpResponse httpResponse = httpCient.execute(httpGet);
77                     //第四步：检查相应的状态是否正常：检查状态码的值是200表示正常
78                     if (httpResponse.getStatusLine().getStatusCode() == 200) {
79                         //第五步：从相应对象当中取出数据，放到entity当中
80                         HttpEntity entity = httpResponse.getEntity();
81                         String response = EntityUtils.toString(entity,"utf-8");//将entity当中的数据转换为字符串
82                         
83                         //在子线程中将Message对象发出去
84                         Message message = new Message();
85                         message.what = SHOW_RESPONSE;
86                         message.obj = response.toString();
87                         handler.sendMessage(message);
88                     }
89                     
90                 } catch (Exception e) {
91                     // TODO Auto-generated catch block
92                     e.printStackTrace();
93                 }
94                 
95             }
96         }).start();//这个start()方法不要忘记了        
97         
98     }    
99 }

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="16" />

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