無法通過Android連接到Web服務

Question

我目前無法在android上連接到我的網絡服務。 我正在使用Jetty Web服務，並使用ANT構建它。 在我的筆記本電腦上，它可以完美運行並顯示數據庫中的項目。 但是，它似乎無法連接到我的Android應用程序。 隨附的代碼和LOGCAT報告。

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.TextView;
public class Android2Servlet extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dbtest);
TextView txtresp = (TextView)findViewById(R.id.servlet_response);

String url = "http://(MY LAPTOPS IP):8085/DB";
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(url);
try{
System.out.println("About to execute");
HttpResponse response = client.execute(request);
String helpedResp=HttpUnpack.request(response); 
System.out.println(helpedResp); 
txtresp.setText(helpedResp);
System.out.println(response);
}catch(Exception ex){
txtresp.setText("Failed!");
ex.printStackTrace();
}
} }

HTTP解壓縮文件

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
public class HttpUnpack {
public static String request(HttpResponse response){
String result = "";
try{ InputStream in = response.getEntity().getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuilder str = new StringBuilder();
String line = null;
while((line = reader.readLine()) != null){
str.append(line + "\n");
}
in.close();
result = str.toString();
}catch(Exception ex){
result = "Error retrieving response";
}
return result;
}
}

HTTP Unpack和Android2Servlet不會導致任何錯誤，但是文本框僅返回“ Failed！”。

LOGCAT文件

W/System.err(1282): android.os.NetworkOnMainThreadException
W/System.err(1282):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
W/System.err(1282):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
W/System.err(1282):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
W/System.err(1282):     at libcore.io.IoBridge.connect(IoBridge.java:112)
W/System.err(1282):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
W/System.err(1282):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
W/System.err(1282):     at java.net.Socket.connect(Socket.java:842)
W/System.err(1282):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
W/System.err(1282):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
W/System.err(1282):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
W/System.err(1282):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
W/System.err(1282):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
W/System.err(1282):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
W/System.err(1282):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
W/System.err(1282):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
W/System.err(1282):     at myFood.myFood.Android2Servlet.onCreate(Android2Servlet.java:24)
W/System.err(1282):     at android.app.Activity.performCreate(Activity.java:4465)
W/System.err(1282):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
W/System.err(1282):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
W/System.err(1282):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
W/System.err(1282):     at android.app.ActivityThread.access$600(ActivityThread.java:123)
W/System.err(1282):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
W/System.err(1282):     at android.os.Handler.dispatchMessage(Handler.java:99)
W/System.err(1282):     at android.os.Looper.loop(Looper.java:137)
W/System.err(1282):     at android.app.ActivityThread.main(ActivityThread.java:4424)
W/System.err(1282):     at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err(1282):     at java.lang.reflect.Method.invoke(Method.java:511)
W/System.err(1282):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
W/System.err(1282):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
W/System.err(1282):     at dalvik.system.NativeStart.main(Native Method)

任何回應將大有幫助。

問候。

編輯：

現在，我刪除了網絡訪問權限，並將其放在另一個Java類中。 並稱之為另一類。 而且它仍然返回相同的錯誤。 還有其他建議嗎？

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
public class androidconnectors {

    public static final String main(String args[]) throws Exception {


String txtresp = "";
try{
    String url = "http://(LAPTOPS IP):8085/Hello";
    HttpClient client = new DefaultHttpClient();
    HttpGet request = new HttpGet(url);
System.out.println("About to execute");
HttpResponse response = client.execute(request);
String helpedResp=HttpUnpack.request(response); // Http Unpack is not part of
System.out.println(helpedResp); // of HttpClient library
txtresp =(helpedResp);
System.out.println(response);
}catch(Exception ex){
    ex.printStackTrace();
}
return txtresp;
}
}

和android類。

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class Settings extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dbtest);
        Button mybutton = (Button) findViewById(R.id.buttonpress);
        mybutton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                TextView txtresp = (TextView)findViewById(R.id.servlet_response);
            String[] args = null;
            try {
                String x = androidconnectors.main(args);
                txtresp.setText(x);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                txtresp.setText("Failed");
            }

            }
        });
}
}

Answer 1

基於快速的Google搜索 ，似乎由於Honeycomb，您不應該在應用程序的主線程上執行網絡訪問（以提高響應速度）。

按照此處的建議創建另一個網絡訪問線程。

Answer 2

您不能更好地使用AsyncTask/Service/IntentService對UI線程進行網絡操作

NetworkOnMainThreadException

當應用程序嘗試在其主線程上執行聯網操作時引發的異常。（從API 11開始）

Answer 3

要解決StrictMode問題，您需要在活動中使用以下代碼-

static{
     StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();  
StrictMode.setThreadPolicy(policy);  
}