Question

如何检索网站中的值？

这是我的java代码，

 public void String[] receive()
    {
    String url="http://shrib.com/content123";

    DefaultHttpClient client = new DefaultHttpClient();
    HttpGet httpGet = new HttpGet(url);
    try {
        HttpResponse execute = client.execute(httpGet);
        InputStream content = execute.getEntity().getContent();

        BufferedReader buffer = new BufferedReader(
                new InputStreamReader(content));
        String s[];
        s=buffer.readLine().split(" ");
        return s;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
  }

运行此代码时，应用程序已停止

AndroidManifest.xml中的

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

也被添加..

然而代码失败了。

例如）考虑www.shrib.com/content123

中的值

 10 20 30 40

每个都用空格隔开所以使用split（＆＃34;＆＃34;）函数来分隔值......

我的堆栈跟踪异常

  android.os.NetworkOnMainThreadException

at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1156)

     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
     at java.net.InetAddress.getAllByName(InetAddress.java:214)
     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:365)
     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:587)
     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:511)
     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:489)
     at vehicle_monitor25.com.example.Main1.receive(Main1.java:182)
     at vehicle_monitor25.com.example.Main1.onCreate(Main1.java:58)
     at android.app.Activity.performCreate(Activity.java:5343)
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088) 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2331)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2429)



       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
       at dalvik.system.NativeStart.main(Native Method)

     java.lang.RuntimeException: Unable to start activity ComponentInfo{vehicle_monitor25.com.example/vehicle_monitor25.com.example.Main1}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2429)
    at android.app.ActivityThread.access$800(ActivityThread.java:151)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1342)
    at android.os.Handler.dispatchMessage(Handler.java:110)
    ... 11 more

执行asyntask后

    public class Main1 extends Activity{
        TextView tv1,tv2,tv3,tv4;
        Button bt1,bt2;
        protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main1);

        int t1,t2,t3,t4;
        String s1,s2,s3,s4;
        t1=10;
        tv1=(TextView) findViewById(R.id.tv1);
        tv1.setText("10");
        new NetworkOperation.execute("");

    }
    public class NetworkOperation extends AsyncTask<Void, Void, Void>
    {

     protected String[] doInBackground(String... params) {
                //Do your network operation here
         String url = "http://www.shrib.com/sridhar123";

            DefaultHttpClient client = new DefaultHttpClient();
         HttpGet httpGet = new HttpGet(url);
         try {
             HttpResponse execute = client.execute(httpGet);
             InputStream content = execute.getEntity().getContent();

             BufferedReader buffer = new BufferedReader(
                     new InputStreamReader(content));
             String s[];
             s=buffer.readLine().split(" ");
             return s;
         } catch (Exception e) {
            e.printStackTrace();
         }

                return null;
            }

            protected void onPostExecute(String[] result) {

                tv1.setText(result[0]);

            }

            @Override
            protected void onPreExecute() {
            }

            @Override
            protected Void doInBackground(Void... params) {
                // TODO Auto-generated method stub
                return null;
            }
    }
}

无法解析NetworkOperation以输入错误

Answer 1

使用asyncTask线程实现网络操作。

class NetworkOperation extends AsyncTask<Void, Void, Void>
{
 @Override
        protected String doInBackground(String... params) {
            //Do your network operation here
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
        }

        @Override
        protected void onPreExecute() {
        }
}

要调用此类，请使用

new NetworkOperation.execute();

如何从Android应用程序中检索网站（URL）的值？

1 个答案: