java - 当我使用内部服务器时，如何解决 IOException 问题。 (Java/安卓)

Question

我当前正在尝试从我的应用程序向我的内部 SQL 服务器发送消息。目前，我通过connection.getOutputStream()语句得到了IOException。我已将相同的代码用于托管服务，一切正常。

我已经使用 DNS 和端口转发从外部访问我的 SQL 服务器，但我仍然收到 IOException。也许有人可以帮助我。内部服务器是使用 Apache2 设置的 Raspberry Pi。

package com.example.myapplication;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.Socket;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import static android.widget.Toast.*;



public class MainActivity extends AppCompatActivity {
 EditText et;
 Button btn;
 TextView tv;

final String scripturlstring = "hostingservice.net";          
//final String scripturlstring = "192.168.178.97:80/index.php";   // Ip adress raspberry pi
@Override

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    et = (EditText) findViewById(R.id.editText);
    tv = (TextView) findViewById(R.id.textView);
    btn = (Button) findViewById(R.id.button);
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(internetAvailable()){
                sendToServer(et.getText().toString());
            }else{
                makeText(getApplicationContext(), "Internet ist nicht Verfügbar", LENGTH_SHORT).show();
            }
        }
    });
}

public void sendToServer(final String text){
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {

                String textparam = "text1=" + URLEncoder.encode(text, "UTF-8");
                tv.setText(textparam);
                URL scripturl = new URL(scripturlstring);
                HttpURLConnection connection = (HttpURLConnection) scripturl.openConnection();


                connection.setDoOutput(true);
                connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
               connection.setFixedLengthStreamingMode(textparam.getBytes().length);

                // Problem entsteht beim connection.getOutputStream

                OutputStreamWriter contentWriter;
                contentWriter = new OutputStreamWriter(connection.getOutputStream());
                contentWriter.write(textparam);
                contentWriter.flush();
                contentWriter.close();


                InputStream answerInputStream = connection.getInputStream();
                final String answer = getTextFromInputStream(answerInputStream);


                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        //Toast.makeText(getApplicationContext(), "noThread", Toast.LENGTH_SHORT).show();

                        tv.setText(answer);

                    }
                });
                answerInputStream.close();
                connection.disconnect();
                connection.close();
            }catch (MalformedURLException e){
                e.printStackTrace();
                tv.setText("Pi hat probleme mit dem MalformedUrlException");
            }catch(IOException e){
                tv.setText("Pi hat probleme mit dem IOexception");
                        //System.err.println("Error creating HTTP connection");
                e.printStackTrace();
            }

        }
    }).start();
}
public String getTextFromInputStream (InputStream is){
    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder stringBuilder = new StringBuilder();
    try {
        String aktuellZeile;
        while((aktuellZeile = reader.readLine()) != null){
        stringBuilder.append(aktuellZeile);
        stringBuilder.append("\n");
    }
    }catch (IOException e){
        e.printStackTrace();
    }

    return stringBuilder.toString().trim();
}
public boolean internetAvailable(){
    ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    return networkInfo != null && networkInfo.isConnected();

 }
}

Answer 1

你肯定还没有添加这个:-

P.S :- Most of the timeI0Exception is for internet connectivity. Please do add

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

在AndroidManifest.xml

我认为 I0Exception 没有其他原因。

另外，在onDestory(...)中停止线程..否则你会得到另一个异常。 (如果线程仍在运行)