Android http

方法一：从应用程序中发起一个HTTP连接。

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1. ImageView iv = new ImageView(context);  
2.  iv.setId(12351);  
3.  String imageUrl = "http://i.pbase.com/o6/92/229792/1/80199697.uAs58yHk.50pxCross_of_the_Knights_Templar_svg.png"; //标准HTTP地址即可  
4.  try {  
5.      URL myurl = new URL(imageUrl);  
6.      HttpURLConnection conn = (HttpURLConnection) myurl.openConnection();  
7.      conn.setDoInput(true);  
8.      conn.connect();  
9.      InputStream is = conn.getInputStream();  
10.      Bitmap bitmap = BitmapFactory.decodeStream(is);  
11.      is.close();  
12.      iv.setImageBitmap(bitmap);  
13.  } catch (Exception e) {  
14.      // TODO: handle exception  
15.  }  
16.  layout.addView(iv);  

在Manifest.xml中加入uses-permission配置，允许进行网络访问

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <manifest xmlns:android="http://schemas.android.com/apk/res/android"  
3.     package="org.studio.crusoe.sample.android" android:versionCode="1"  
4.     android:versionName="1.0">  
5.     <uses-permission android:name="android.permission.INTERNET" />  
6.     <application android:icon="@drawable/icon" android:label="@string/app_name">  
7.         <activity android:name=".ActivityMain" android:label="@string/app_name">  
8.             <intent-filter>  
9.                 <action android:name="android.intent.action.MAIN" />  
10.                 <category android:name="android.intent.category.LAUNCHER" />  
11.             </intent-filter>  
12.         </activity>  
13.   
14.     </application>  
15.     <uses-sdk android:minSdkVersion="2" />  
16.   
17. </manifest>   

方法二：使用Apache API：

1、使用Map来存储参数

Map<String, String> map = new HashMap<String, String>();
map.put(“name”, “wusheng”);
map.put(“password”, “pwd”);

2、使用DefaultHttpClient创建HttpClient实例

DefaultHttpClient httpClient = new DefaultHttpClient();

3、构建HttpPost

HttpPost post = new HttpPost(“http://wu-sheng.iteye.com”);

4、将由Map存储的参数转化为键值参数

List<BasicNameValuePair> postData = new ArrayList<BasicNameValuePair>();
for (Map.Entry<String, String> entry : map.entrySet()) {
postData.add(new BasicNameValuePair(entry.getKey(),
entry.getValue()));
}

5、使用编码构建Post实体

UrlEncodedFormEntity entity = new UrlEncodedFormEntity(
postData, HTTP.UTF_8);

6、设置Post实体

post.setEntity(entity);

7、执行Post方法

HttpResponse response = httpClient.execute(post);

8、获取返回实体

HttpEntity httpEntity = response.getEntity();

9、将H中返回实体转化为输入流

InputStream is = httpEntity.getContent();

10、读取输入流，即返回文本内容

StringBuffer sb = new StringBuffer();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line = “”;
while((line=br.readLine())!=null){
sb.append(line);
}

例如：Android 通过Http访问Web端的Servlet

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1. //Http工具类   
2. import org.apache.http.HttpResponse;   
3. import org.apache.http.HttpStatus;   
4. import org.apache.http.client.HttpClient;   
5. import org.apache.http.client.methods.HttpGet;   
6. import org.apache.http.impl.client.DefaultHttpClient;   
7. import org.apache.http.params.BasicHttpParams;   
8. import org.apache.http.params.HttpConnectionParams;   
9. import org.apache.http.params.HttpParams;   
10. import org.apache.http.util.EntityUtils;   
11.    
12. public class HttpUtil {   
13.     public static String getHttpJSON(String url) {   
14.         HttpGet httpRequest = new HttpGet(url);   
15.         try {   
16.             HttpClient httpclient = new DefaultHttpClient();   
17.             HttpResponse httpResponse = httpclient.execute(httpRequest);   
18.    
19.             if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {   
20.                 String jsonStr = EntityUtils.toString(httpResponse.getEntity(),   
21.                         "UTF-8");   
22.                 return jsonStr;   
23.             }   
24.         } catch (Exception e) {   
25.             e.printStackTrace();   
26.             System.out.println("==============e.printStackTrace() : "   
27.                     + e.getMessage());   
28.         }   
29.         return null;   
30.     }   
31.    
32.     public static int getHttpStatus() {   
33.         int status = 0;   
34.         HttpGet httpRequest = new HttpGet(   
35.                 "http://192.168.0.214/vote/AndroidConnServlet");   
36.         try {   
37.             HttpParams httpParameters = new BasicHttpParams();   
38.             HttpConnectionParams.setConnectionTimeout(httpParameters, 5000);   
39.             HttpConnectionParams.setSoTimeout(httpParameters, 5000);   
40.             HttpConnectionParams.setTcpNoDelay(httpParameters, true);   
41.                
42.             HttpClient httpclient = new DefaultHttpClient(httpParameters);   
43.             HttpResponse httpResponse = httpclient.execute(httpRequest);   
44.    
45.             status = httpResponse.getStatusLine().getStatusCode();   
46.         } catch (Exception e) {   
47.             e.printStackTrace();   
48.             System.out   
49.                     .println("==============connection wifi fail,e.printStackTrace() : "   
50.                             + e.getMessage());   
51.         }   
52.         return status;   
53.     }   
54.    
55. }   
56.    
57. //调用方法   
58. public void ensureVote() {   
59.             String URL = "http://192.168.0.214/vote/VoteServlet";   
60.             codeText = codeEdit.getText().toString();   
61.             if (codeText == null || codeText.length() == 0) {   
62.                 Toast.makeText(VoteActivity.this, "投票失败,请输入投票码.",   
63.                         Toast.LENGTH_LONG).show();   
64.                 return;   
65.             }   
66.             URL = URL + "?project=" + radioVoteText + "&voteCode=" + codeText   
67.                     + "&source=Android";   
68.                
69.             String httpStatus = "0";   
70.             httpStatus = HttpUtil.getHttpJSON(URL);   
71.             if (httpStatus != null && httpStatus.equals("1")) {   
72.                 new AlertDialog.Builder(VoteActivity.this).setTitle("success")   
73.                         .setMessage("投票成功,非常感谢.").setNeutralButton("返回",   
74.                                 new DialogInterface.OnClickListener() {   
75.                                     public void onClick(DialogInterface dlg,   
76.                                             int sumthin) {   
77.                                     }   
78.                                 }).show();   
79.             } else if (httpStatus != null && httpStatus.equals("2")) {   
80.                 new AlertDialog.Builder(VoteActivity.this).setTitle("warn")   
81.                         .setMessage("投票失败,投票码已经使用.").setNeutralButton("返回",   
82.                                 new DialogInterface.OnClickListener() {   
83.                                     public void onClick(DialogInterface dlg,   
84.                                             int sumthin) {   
85.                                     }   
86.                                 }).show();   
87.             } else if (httpStatus != null && httpStatus.equals("0")) {   
88.                 new AlertDialog.Builder(VoteActivity.this).setTitle("error")   
89.                         .setMessage("投票失败,请联系网管.").setNeutralButton("返回",   
90.                                 new DialogInterface.OnClickListener() {   
91.                                     public void onClick(DialogInterface dlg,   
92.                                             int sumthin) {   
93.                                     }   
94.                                 }).show();   
95.             }   
96.    
97.         }   
98.     }