Question

我按照AsyncTask的本教程获取以下错误日志：

03-23 11:44:42.936: WARN/System.err(315): java.net.UnknownHostException: www.google.co.in  
03-23 11:44:42.936: WARN/System.err(315):     at java.net.InetAddress.lookupHostByName(InetAddress.java:513)  
03-23 11:44:42.936: WARN/System.err(315):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:278)  
03-23 11:44:42.936: WARN/System.err(315):     at java.net.InetAddress.getAllByName(InetAddress.java:242)  
03-23 11:44:42.936: WARN/System.err(315):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136)  
03-23 11:44:42.936: WARN/System.err(315):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)    
03-23 11:44:42.936: WARN/System.err(315):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
03-23 11:44:42.936: WARN/System.err(315):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:348)  
03-23 11:44:42.936: WARN/System.err(315):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
03-23 11:44:42.936: WARN/System.err(315):       at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
03-23 11:44:42.944: WARN/System.err(315):     at    org.apache.http.impl.client.AbstractHttpC  lient.execute(AbstractHttpClient.java:465)
03-23 11:44:42.944: WARN/System.err(315):     at com.test.async.AsyncTaskExampleActivity$DownloadWebPageTask.doInBackground   (AsyncTaskExampleActivity.java:36)
03-23 11:44:42.944: WARN/System.err(315):     at com.test.async.AsyncTaskExampleActivity$DownloadWebPageTask.doInBackground    (AsyncTaskExampleActivity.java:1)  
03-23 11:44:42.944: WARN/System.err(315):     at android.os.AsyncTask$2.call(AsyncTask.java:185)  
03-23 11:44:42.944: WARN/System.err(315):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
03-23 11:44:42.944: WARN/System.err(315):     at java.util.concurrent.FutureTask.run   (FutureTask.java:137)  
03-23 11:44:42.944: WARN/System.err(315):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
03-23 11:44:42.944: WARN/System.err(315):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
03-23 11:44:42.944: WARN/System.err(315):     at java.lang.Thread.run(Thread.java:1096)

我该如何解决？

我的代码：

 public class AsyncTaskExampleActivity extends Activity {  
    private TextView textView;

    /** Called when the activity is first created. */
        @Override
            public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
             setContentView(R.layout.main);
             textView = (TextView) findViewById(R.id.TextView01);
     }

    private class DownloadWebPageTask extends AsyncTask<String, Void, String> {
       @Override
        protected String doInBackground(String... urls) {
          String response = "";
           Log.i("", "in doInBackgroundddddddddd..........");
           Log.i("", "in readWebpageeeeeeeeeeeee");
           /*
           * try { InetAddress i =
           * InetAddress.getByName("http://google.co.in"); } catch
           * (UnknownHostException e1) { e1.printStackTrace(); }
           */
          for (String url : urls) {
            Log.i("", "in for looooooop doInBackgroundddddddddd..........");
            DefaultHttpClient client = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(url);
            try {
                Log
                        .i("",
                                "afetr for looooooop try doInBackgroundddddddddd..........");
                HttpResponse execute = client.execute(httpGet); 
                Log
                        .i("",
                                "afetr for looooooop try client ..execute doInBackgroundddddddddd..........");
                InputStream content = execute.getEntity().getContent();

                BufferedReader buffer = new BufferedReader(
                        new InputStreamReader(content));
                String s = "";
                while ((s = buffer.readLine()) != null) {
                    response += s;
                    Log
                            .i("",
                                    "afetr while looooooop try client ..execute doInBackgroundddddddddd..........");
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        Log
                .i("",
                        "afetr lasttttttttttttt b4 response  doInBackgroundddddddddd..........");
        return response;
    }

    @Override
    protected void onPostExecute(String result) {
        Log.i("", "in onPostExecuteeee..........");
        textView.setText(result);
    }
}

public void readWebpage(View view) {
    /*
     * System.setProperty("http.proxyHost", "10.132.116.10");
     * System.setProperty("http.proxyPort", "3128");
     */

    DownloadWebPageTask task = new DownloadWebPageTask();
    task.execute(new String[] { "http://google.co.in" });
    Log.i("", "in readWebpageeeeeeeeeeeee after execute..........");

}

}

main.xml：

<Button android:id="@+id/readWebpage" android:layout_width="match_parent"
    android:layout_height="wrap_content" android:onClick="readWebpage"
    android:text="Load Webpage">
</Button>

<TextView android:id="@+id/TextView01" android:layout_width="match_parent"
    android:layout_height="match_parent" android:text="Example Text">
</TextView>

清单：

<?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.test.async" android:versionCode="1" android:versionName="1.0">
   <uses-sdk android:minSdkVersion="8" />
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
  <application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".AsyncTaskExampleActivity"
        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>

感谢
斯纳

Answer 1

在调用网络之前，只需添加以下两行：

try { InetAddress i = InetAddress.getByName("YourDesiredURL"); }
catch (UnknownHostException e1) { e1.printStackTrace(); }

您不需要捕获任何异常，只需在Web调用之前执行它。有关详细信息，请阅读this

Answer 2

尝试了你的代码并得到了同样的错误来解决错误，我替换了两行代码

HttpGet httpGet = new HttpGet(url); 
HttpResponse execute = client.execute(httpGet);

通过，

HttpPost httppost = new HttpPost(url); 
HttpResponse execute = client.execute(httppost);

编辑：

在创建HttpClient对象后添加此行。

HttpConnectionParams.setConnectionTimeout(client.getParams(),
                        20000); // Timeout Limit

Answer 3

转到Windows命令提示符以了解google ip地址。输入“ping www.google.com” 您将获得谷歌的IP，然后使用IP而不是谷歌网址。如果网络连接可用并且您拥有正确的清单权限，那么此步骤必须帮助您... 玩得开心

这是代码 -

使用此IP而不是www.google.co.in，因为本地计算机中的模拟器无法将网址转换为相应的IP。如果您使用连接到代理服务器的计算机，则它不会出现此问题。并且您的设备能够运行此应用程序。此ip转换仅适用于此模拟器。

public static String GOOGLE_IP = "http://74.125.236.183";

public static String getContent(String url) throws Exception {
     return(new Scanner(new URL(url).openConnection().getInputStream()).useDelimiter("/z").next());
}

asyncTask中的Android UnknownHost - 加载网页

3 个答案: