创建套接字时Android客户端失败

Question

我正在编写一个Android应用程序，以使用套接字连接到服务器。我已经搜索了代码示例，显然我做的与其他人一样，但是当创建套接字时，应用程序停止工作，我无法找到原因。

失败的行是：

package com.example.javi.androidclientapp;

import android.app.AlertDialog;
import android.content.DialogInterface;
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 java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class MainActivity extends AppCompatActivity {

    private Socket socket;
    String message = "";
    InputStream inputStream;
    BufferedReader bufread;
    TextView msg;
    Thread ClientThread;

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

        final EditText server_ip = (EditText) findViewById(R.id.ip);
        final EditText server_port = (EditText) findViewById(R.id.port);
        final Button button = (Button) findViewById(R.id.connect);
        msg = (TextView) findViewById(R.id.msg);
        ClientThread = new Thread(new ClientThread());

        button.setOnClickListener(new Button.OnClickListener(){
            public void onClick(View view){
                String btxt = button.getText().toString();
                if(btxt.equalsIgnoreCase("Connect")){
                    try {
                        InetAddress serverAddr = InetAddress.getByName(server_ip.getText().toString());

                        /***** The line below fails: ****/
                        socket = new Socket(serverAddr, Integer.parseInt(server_port.getText().toString()));

                        button.setText("Disconnect");
                        inputStream = socket.getInputStream();
                        bufread = new BufferedReader(new InputStreamReader(inputStream));
                        ClientThread.start();
                    } catch (UnknownHostException e1) {
                        e1.printStackTrace();
                        alertOneButton(e1.toString());
                    } catch (IOException e1) {
                        e1.printStackTrace();
                        alertOneButton(e1.toString());
                    }
                }else{
                    try{
                        socket.close();
                    }catch (UnknownHostException e2){
                        e2.printStackTrace();
                        alertOneButton(e2.toString());
                    } catch (IOException e2) {
                        e2.printStackTrace();
                        alertOneButton(e2.toString());
                    }
                    button.setText("Connect");
                }
            }
        });
    }

    class ClientThread implements Runnable {

        @Override
        public void run() {

            while (socket.isConnected()) {
                String s_tmp = "";
                try {
                    s_tmp = bufread.readLine();
                    if(!s_tmp.isEmpty()){
                        message += s_tmp + "\n";

                        MainActivity.this.runOnUiThread(new Runnable() {

                            @Override
                            public void run() {
                                msg.setText(message);
                            }
                        });
                    }

                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                    message += "Something wrong! " + e.toString() + "\n";
                    alertOneButton(message);
                }

            }

        }

    }
    /*
 * AlertDialog with one action button.
 */
    public void alertOneButton(String msg) {

        new AlertDialog.Builder(MainActivity.this)
                .setTitle("Dialog Simple")
                .setMessage(msg.toString())
                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                }).show();
    }
}

这是我的完整代码：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.javi.androidclientapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
</manifest>

清单：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="WSentinel Data Receiver"
        android:textStyle="bold" />
    <EditText
        android:id="@+id/ip"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="172.30.200.110"
        android:inputType="text"
        />
    <EditText
        android:id="@+id/port"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="8082"
        android:inputType="text"
        />
    <Button
        android:id="@+id/connect"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Connect"
        />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <TextView
            android:id="@+id/msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </ScrollView>

</LinearLayout>

布局：

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我完全迷失在这里，任何小费都将受到赞赏！

Thnks