Android 数据请求

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

 

1.<?xmlversion="1.0"encoding="utf-8"?>  
2.<manifestxmlns: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-permissionandroid:name="android.permission.INTERNET"/>  
6.    <applicationandroid:icon="@drawable/icon"android:label="@string/app_name">  
7.        <activityandroid:name=".ActivityMain"android:label="@string/app_name">  
8.            <intent-filter>  
9.                <actionandroid:name="android.intent.action.MAIN"/>  
10.                <categoryandroid:name="android.intent.category.LAUNCHER"/>  
11.            </intent-filter>  
12.        </activity>  
13.  
14.    </application>  
15.    <uses-sdkandroid: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

 

 

 

//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();
            }

        }
    }