示例:使用AsyncTask的Android双向networking套接字

我在Android上find的大部分networking套接字示例都是单向的。 我需要一个双向数据stream的解决scheme。 我最终得知了AsyncTask。 这个例子展示了如何从套接字获取数据并将数据发回给它。 由于正在接收数据的套接字的阻塞性质,阻塞需要在UI线程以外的线程中运行。

为了举例,这个代码连接到一个web服务器。 按“启动AsyncTask”button将打开套接字。 一旦套接字打开,Web服务器等待请求。 按下“发送消息”button将向服务器发送请求。 任何来自服务器的响应都将显示在TextView中。 在http的情况下,一旦所有数据已经​​发送,web服务器将与客户端断开连接。 对于其他TCP数据stream,连接将保持直到一方断开。

截图:

应用程序屏幕截图

AndroidManifest.xml中:

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

水库\布局\ main.xml中:

 <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <Button android:id="@+id/btnStart" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Start AsyncTask"></Button> <Button android:id="@+id/btnSend" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Send Message"></Button> <TextView android:id="@+id/textStatus" android:textSize="24sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Status Goes Here" /> </LinearLayout> 

SRC \ com.exampleasynctask \ MainActivity.java:

 package com.exampleasynctask; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.InetSocketAddress; import java.net.Socket; import java.net.SocketAddress; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.TextView; public class MainActivity extends Activity { Button btnStart, btnSend; TextView textStatus; NetworkTask networktask; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btnStart = (Button)findViewById(R.id.btnStart); btnSend = (Button)findViewById(R.id.btnSend); textStatus = (TextView)findViewById(R.id.textStatus); btnStart.setOnClickListener(btnStartListener); btnSend.setOnClickListener(btnSendListener); networktask = new NetworkTask(); //Create initial instance so SendDataToNetwork doesn't throw an error. } private OnClickListener btnStartListener = new OnClickListener() { public void onClick(View v){ btnStart.setVisibility(View.INVISIBLE); networktask = new NetworkTask(); //New instance of NetworkTask networktask.execute(); } }; private OnClickListener btnSendListener = new OnClickListener() { public void onClick(View v){ textStatus.setText("Sending Message to AsyncTask."); networktask.SendDataToNetwork("GET / HTTP/1.1\r\n\r\n"); } }; public class NetworkTask extends AsyncTask<Void, byte[], Boolean> { Socket nsocket; //Network Socket InputStream nis; //Network Input Stream OutputStream nos; //Network Output Stream @Override protected void onPreExecute() { Log.i("AsyncTask", "onPreExecute"); } @Override protected Boolean doInBackground(Void... params) { //This runs on a different thread boolean result = false; try { Log.i("AsyncTask", "doInBackground: Creating socket"); SocketAddress sockaddr = new InetSocketAddress("192.168.1.1", 80); nsocket = new Socket(); nsocket.connect(sockaddr, 5000); //10 second connection timeout if (nsocket.isConnected()) { nis = nsocket.getInputStream(); nos = nsocket.getOutputStream(); Log.i("AsyncTask", "doInBackground: Socket created, streams assigned"); Log.i("AsyncTask", "doInBackground: Waiting for inital data..."); byte[] buffer = new byte[4096]; int read = nis.read(buffer, 0, 4096); //This is blocking while(read != -1){ byte[] tempdata = new byte[read]; System.arraycopy(buffer, 0, tempdata, 0, read); publishProgress(tempdata); Log.i("AsyncTask", "doInBackground: Got some data"); read = nis.read(buffer, 0, 4096); //This is blocking } } } catch (IOException e) { e.printStackTrace(); Log.i("AsyncTask", "doInBackground: IOException"); result = true; } catch (Exception e) { e.printStackTrace(); Log.i("AsyncTask", "doInBackground: Exception"); result = true; } finally { try { nis.close(); nos.close(); nsocket.close(); } catch (IOException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } Log.i("AsyncTask", "doInBackground: Finished"); } return result; } public void SendDataToNetwork(String cmd) { //You run this from the main thread. try { if (nsocket.isConnected()) { Log.i("AsyncTask", "SendDataToNetwork: Writing received message to socket"); nos.write(cmd.getBytes()); } else { Log.i("AsyncTask", "SendDataToNetwork: Cannot send message. Socket is closed"); } } catch (Exception e) { Log.i("AsyncTask", "SendDataToNetwork: Message send failed. Caught an exception"); } } @Override protected void onProgressUpdate(byte[]... values) { if (values.length > 0) { Log.i("AsyncTask", "onProgressUpdate: " + values[0].length + " bytes received."); textStatus.setText(new String(values[0])); } } @Override protected void onCancelled() { Log.i("AsyncTask", "Cancelled."); btnStart.setVisibility(View.VISIBLE); } @Override protected void onPostExecute(Boolean result) { if (result) { Log.i("AsyncTask", "onPostExecute: Completed with an Error."); textStatus.setText("There was a connection error."); } else { Log.i("AsyncTask", "onPostExecute: Completed."); } btnStart.setVisibility(View.VISIBLE); } } @Override protected void onDestroy() { super.onDestroy(); networktask.cancel(true); //In case the task is currently running } } 

您的SendDataToNetwork不会与doInBackground()在同一个线程上运行。 在套接字准备就绪之前, SendDataToNetwork可能会开始发送数据。

为了避免这一切,只需使用SendDataToNetwork将数据和信号保存到后台线程即可以发送数据。

由于用户可能会多次按下button,而旧数据仍在发送中,您应该在NetworkTask中同步Queue。 然后:

  1. 后台线程build立套接字连接,然后进入hibernate状态(通过wait())。
  2. 按下button, SendDataToNetwork将数据添加到队列中,并通过notify()唤醒后台线程。
  3. 当后台线程唤醒时,它首先检查finish标志。 如果设置,则closures连接并退出。 如果没有,则从队列读取数据,将其发送到networking并返回到睡眠状态。
  4. 你应该有finish()方法,它设置一个finish标志(primefacesvariables,如布尔),并唤醒后台线程。 这是正常退出后台线程的一种方法。

看看如何完成线程同步: http : //www.jchq.net/tutorial/07_03Tut.htm

SendDataToNetwork任务在主UI线程中运行,这意味着由于NetworkOnMainThreadException致命的exception,它将使Honeycomb或更高级别的应用程序崩溃。 这是我的SendDataToNetwork看起来像避免这个问题:

 public boolean sendDataToNetwork(final byte[] cmd) { if (_nsocket.isConnected()) { Log.i(TAG, "SendDataToNetwork: Writing received message to socket"); new Thread(new Runnable() { public void run() { try { _nos.write(cmd); } catch (Exception e) { e.printStackTrace(); Log.i(TAG, "SendDataToNetwork: Message send failed. Caught an exception"); } } }).start(); return true; } Log.i(TAG, "SendDataToNetwork: Cannot send message. Socket is closed"); return false; } 

更多互动的例子

与OP类似,但是您可以控制主机,端口和消息,如果连接失败,则会popup错误通知。

在这里输入图像描述

用法1:

  • 在局域网上获取Android和Linux桌面
  • ifconfigfind桌面的IP
  • 在terminal上运行netcat -l 12345
  • 在Android上,填写桌面的IP
  • 点击联系服务器
  • 在terminal上input回复,然后Ctrl + D
  • 它出现在output:部分

用法2:

  • 主机名google.com
  • 港口80
  • 消息: "GET / HTTP/1.1\r\nHost: google.com\r\n\r\n"

请注意,某些HTTP服务器在应答预期到进一步请求后将不会closures,并且应用程序将挂起直到超时。 这样的服务器希望你parsingContent-Width头并closures你自己。

如果连接失败,则会在对话框中向用户显示警报消息。

添加到AndroidManifest.xml

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

主要活动是:

 import android.app.Activity; import android.app.AlertDialog; import android.app.IntentService; import android.content.DialogInterface; import android.content.Intent; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.LinearLayout; import android.widget.ScrollView; import android.widget.TextView; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.Socket; public class Main extends Activity { final static String TAG = "AndroidCheatSocket"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); final LinearLayout linearLayout = new LinearLayout(this); linearLayout.setOrientation(LinearLayout.VERTICAL); TextView textView; final String defaultHostname = "192.168.0."; textView = new TextView(this); textView.setText("hostname / IP:"); linearLayout.addView(textView); final EditText hostnameEditText = new EditText(this); hostnameEditText.setText(defaultHostname); hostnameEditText.setSingleLine(true); linearLayout.addView(hostnameEditText); textView = new TextView(this); textView.setText("port:"); linearLayout.addView(textView); final EditText portEditText = new EditText(this); portEditText.setText("12345"); portEditText.setSingleLine(true); linearLayout.addView(portEditText); textView = new TextView(this); textView.setText("data to send:"); linearLayout.addView(textView); final EditText dataEditText = new EditText(this); dataEditText.setText(String.format("GET / HTTP/1.1\r\nHost: %s\r\n\r\n", defaultHostname)); linearLayout.addView(dataEditText); final TextView replyTextView = new TextView(this); final ScrollView replyTextScrollView = new ScrollView(this); replyTextScrollView.addView(replyTextView); final Button button = new Button(this); button.setText("contact server"); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { button.setEnabled(false); new MyAsyncTask(Main.this, replyTextView, button).execute( hostnameEditText.getText().toString(), portEditText.getText().toString(), dataEditText.getText().toString()); } }); linearLayout.addView(button); textView = new TextView(this); textView.setText("output:"); linearLayout.addView(textView); linearLayout.addView(replyTextScrollView); this.setContentView(linearLayout); } private class MyAsyncTask extends AsyncTask<String, Void, String> { Activity activity; Button button; TextView textView; IOException ioException; MyAsyncTask(Activity activity, TextView textView, Button button) { super(); this.activity = activity; this.textView = textView; this.button = button; this.ioException = null; } @Override protected String doInBackground(String... params) { StringBuilder sb = new StringBuilder(); try { Socket socket = new Socket( params[0], Integer.parseInt(params[1])); OutputStream out = socket.getOutputStream(); out.write(params[2].getBytes()); InputStream in = socket.getInputStream(); byte buf[] = new byte[1024]; int nbytes; while ((nbytes = in.read(buf)) != -1) { sb.append(new String(buf, 0, nbytes)); } socket.close(); } catch(IOException e) { this.ioException = e; return "error"; } return sb.toString(); } @Override protected void onPostExecute(String result) { if (this.ioException != null) { new AlertDialog.Builder(this.activity) .setTitle("An error occurrsed") .setMessage(this.ioException.toString()) .setIcon(android.R.drawable.ic_dialog_alert) .show(); } else { this.textView.setText(result); } this.button.setEnabled(true); } } } 

在GitHub上构build样板 。

我也发布了一个Android服务器的例子: https : //stackoverflow.com/a/35745834/895245

testing在Android 5.1.1,索尼Xperia 3 D6643。