Android HTTP请求访问的方法

方法一：从应用程序中发起一个HTTP连接。

       ImageView iv = new ImageView(context);        iv.setId(12351);        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        try {            URL myurl = new URL(imageUrl);            HttpURLConnection conn = (HttpURLConnection) myurl.openConnection();            conn.setDoInput(true);            conn.connect();            InputStream is = conn.getInputStream();            Bitmap bitmap = BitmapFactory.decodeStream(is);            is.close();            iv.setImageBitmap(bitmap);        } catch (Exception e) {            // TODO: handle exception        }        layout.addView(iv);

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

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"package="org.studio.crusoe.sample.android" android:versionCode="1"android:versionName="1.0"><uses-permission android:name="android.permission.INTERNET" /><application android:icon="@drawable/icon" android:label="@string/app_name"><activity android:name=".ActivityMain" android:label="@string/app_name"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity></application><uses-sdk android:minSdkVersion="2" /></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

//Http工具类 import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.params.BasicHttpParams; import org.apache.http.params.HttpConnectionParams; import org.apache.http.params.HttpParams; import org.apache.http.util.EntityUtils;  public class HttpUtil {     public static String getHttpJSON(String url) {         HttpGet httpRequest = new HttpGet(url);         try {             HttpClient httpclient = new DefaultHttpClient();             HttpResponse httpResponse = httpclient.execute(httpRequest);              if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {                 String jsonStr = EntityUtils.toString(httpResponse.getEntity(),                         "UTF-8");                 return jsonStr;             }         } catch (Exception e) {             e.printStackTrace();             System.out.println("==============e.printStackTrace() : "                     + e.getMessage());         }         return null;     }      public static int getHttpStatus() {         int status = 0;         HttpGet httpRequest = new HttpGet(                 "http://192.168.0.214/vote/AndroidConnServlet");         try {             HttpParams httpParameters = new BasicHttpParams();             HttpConnectionParams.setConnectionTimeout(httpParameters, 5000);             HttpConnectionParams.setSoTimeout(httpParameters, 5000);             HttpConnectionParams.setTcpNoDelay(httpParameters, true);                          HttpClient httpclient = new DefaultHttpClient(httpParameters);             HttpResponse httpResponse = httpclient.execute(httpRequest);              status = httpResponse.getStatusLine().getStatusCode();         } catch (Exception e) {             e.printStackTrace();             System.out                     .println("==============connection wifi fail,e.printStackTrace() : "                             + e.getMessage());         }         return status;     }  }  //调用方法 public void ensureVote() {             String URL = "http://192.168.0.214/vote/VoteServlet";             codeText = codeEdit.getText().toString();             if (codeText == null || codeText.length() == 0) {                 Toast.makeText(VoteActivity.this, "投票失败,请输入投票码.",                         Toast.LENGTH_LONG).show();                 return;             }             URL = URL + "?project=" + radioVoteText + "&voteCode=" + codeText                     + "&source=Android";                          String httpStatus = "0";             httpStatus = HttpUtil.getHttpJSON(URL);             if (httpStatus != null && httpStatus.equals("1")) {                 new AlertDialog.Builder(VoteActivity.this).setTitle("success")                         .setMessage("投票成功,非常感谢.").setNeutralButton("返回",                                 new DialogInterface.OnClickListener() {                                     public void onClick(DialogInterface dlg,                                             int sumthin) {                                     }                                 }).show();             } else if (httpStatus != null && httpStatus.equals("2")) {                 new AlertDialog.Builder(VoteActivity.this).setTitle("warn")                         .setMessage("投票失败,投票码已经使用.").setNeutralButton("返回",                                 new DialogInterface.OnClickListener() {                                     public void onClick(DialogInterface dlg,                                             int sumthin) {                                     }                                 }).show();             } else if (httpStatus != null && httpStatus.equals("0")) {                 new AlertDialog.Builder(VoteActivity.this).setTitle("error")                         .setMessage("投票失败,请联系网管.").setNeutralButton("返回",                                 new DialogInterface.OnClickListener() {                                     public void onClick(DialogInterface dlg,                                             int sumthin) {                                     }                                 }).show();             }          }     }